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Best Orbital Relationship of All Time

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    1
    V1974 Cygni

    V1974 Cygni

    V1974 Cygni or Nova Cygni 1992 was a relatively bright nova in the constellation Cygnus. It was discovered on February 19, 1992 by Peter Collins. At that time it was magnitude 6, the maximum magnitude reached was 4.4. The hydrogen burning on the white dwarf ended two years later, in 1994. This nova was a neon nova. It is the first nova observed from onset to completion, and can be calculated to be 10,430 light years away from Earth.
    7.56
    9 votes
    2
    Beta Cassiopeiae

    Beta Cassiopeiae

    Beta Cassiopeiae (β Cas, β Cassiopeiae) is a Delta Scuti variable star in the constellation Cassiopeia. It is a subgiant or giant star belonging to the spectral class F2, with a mean apparent magnitude of +2.27 and absolute magnitude of +1.16. It has the traditional name Caph, from the Arabic word كف kaf, "palm" (i.e. reaching from the Pleiades), also known as Al Sanām al Nākah. Another Arabic name is al-Kaff al-Khadib. With a mean apparent magnitude (V-band) of +2.27, it is one of the five stars which make up the 'W' of Cassiopeia, adjacent to the just brighter Schedar (Alpha Cassiopeiae). SN 1572, traditionally known as Tycho's Star, appeared about 5 degrees to the northwest of Caph in 1572. As a star in the deep northern hemisphere of the sky, Beta Cassiopeiae is prominent to viewers in the northern hemisphere but not often seen by those in the southern hemisphere. The constellation of Cassiopeia does not rise above the horizon to viewers in Tasmania, and only low if one were in Cairns. β Cassiopeiae is a yellow-white hued subgiant or giant of stellar class F2III-IV, with a surface temperature of 6,700 Kelvin. More than three times the size of and 28 times brighter than the sun,
    8.43
    7 votes
    3
    Omicron Arietis

    Omicron Arietis

    Omicron Arietis (ο Ari, ο Arietis) is the Bayer designation for a star in the northern constellation of Aries. Based upon an annual parallax shift of 5.49 ± 0.32 mas, it is 594 ± 35 light-years (182 ± 11 parsecs) distant from Earth. This star has an apparent visual magnitude of +5.78, which means it is dimly visible to the naked eye. This is a B-type main sequence star with a stellar classification of B9 Vn. The 'n' suffix indicates that is has nebulous absorption lines in its spectrum, which are caused by the Doppler effect and rapid rotation. Indeed, it has a projected rotational velocity of 225 km/s.
    7.29
    7 votes
    4
    Gamma Apodis

    Gamma Apodis

    Gamma Apodis (γ Aps, γ Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. From parallax measurements, the distance to this star can be estimated as 156 light-years (48 pc). It is visible to the naked eye with an apparent visual magnitude of 3.86. A stellar classification of G9 III identifies it as a giant star in the later stages of its evolution. It is an active X-ray source with a luminosity of 1.607 × 10 erg s, making it one of the 100 strongest stellar X-ray sources within 50 parsecs of the Sun. In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of γ Apodis, ζ Apodis, ι Apodis, β Apodis, δ Octantis, δ Apodis, η Apodis, α Apodis and ε Apodis. Consequently, γ Apodis itself is known as 異雀四 (Yì Què sì, English: the Fourth Star of Exotic Bird.)
    8.80
    5 votes
    5
    VV Cephei

    VV Cephei

    VV Cephei, also known as HD 208816, is an eclipsing binary star system located in the constellation Cepheus, approximately 5,000 light years from Earth. A red supergiant fills the system's Roche lobe when closest to its companion blue star, the latter appearing to be on the main sequence. Matter flows from the red supergiant onto the blue companion for at least part of the orbit and the hot star is obscured by a large disk of material. The red supergiant primary, known as VV Cephei A, is currently recognised as one of the largest stars in the galaxy, with an estimated solar radius between 1,050 and 1,900. Although VV Cephei is an extremely large star showing high mass loss and having some emissions lines, the spectral luminosity class and absolute magnitude do not qualify it as a hypergiant. It should be possible to calculate the masses of eclipsing binary stars with some accuracy, but in this case mass loss, changes in the orbital parameters, a disk obscuring the hot secondary, and doubt about the distance of the system have led to wildly varying estimates. Calculations before the most recent primary and secondary eclipses had started to settle on masses of around 20 for both
    7.50
    6 votes
    6
    Epsilon Andromedae

    Epsilon Andromedae

    Epsilon Andromedae (Epsilon And, ε Andromedae, ε And) is a G-type giant star in the constellation of Andromeda. It has an apparent visual magnitude of approximately 4.37. ε Andromedae is believed to be a red clump star which is fusing helium in its core. Its orbit in the Milky Way is highly eccentric, causing it to move rapidly relative to the Sun and its neighboring stars. In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of ε Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, δ Andromedae, π Andromedae, ν Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, ε Andromedae itself is known as 奎宿四 (Kuí Sù sì, English: the Fourth Star of Legs.)
    8.40
    5 votes
    7
    Mu Aquarii

    Mu Aquarii

    Mu Aquarii (μ Aqr, μ Aquarii) is the Bayer designation for a binary star in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent magnitude of 4.7. Based upon parallax measurements, the distance to this system is about 157 light-years (48 parsecs). Mu Aquarii is a spectroscopic binary system with an orbital period of 1,566 days and an eccentricity of 0.23. The combined spectrum matches a stellar classification of A3m, with the 'm' suffix indicating that this is an Am, or chemically peculiar star. This star system shares the traditional name Albulaan with ν Aquarii. The name derives from an Arabic term al-bulaān (ألبولعان) meaning "the two swallowers". This star, along with ε Aqr (Albali) and ν Aqr (Albulaan), were al Bulaʽ (البلع), the Swallower. In Chinese, 奎宿 (Nǚ Sù), meaning Girl (asterism) (or Woman), refers to an asterism consisting of μ Aquarii, ε Aquarii, 4 Aquarii, 5 Aquarii and 3 Aquarii. Consequently, μ Aquarii itself is known as 女宿二 (Nǚ Sù èr, English: the Second Star of Girl / Woman.)
    8.40
    5 votes
    8
    Maia

    Maia

    Maia (20 Tauri) is a star in the constellation Taurus. It is the fourth brightest star in the Pleiades open star cluster (M45), after Alcyone, Atlas and Electra, in that order. The name Maia originates with the Greek: Μαῖα and Latin: Maia. She is one of the seven daughters of Atlas and Pleione in Greek mythology—stars which are also included in the Pleaides star cluster (see map). Maia is a blue giant of spectral type B8 III, and a mercury-manganese star. Maia's visual magnitude is 3.871, requiring darker skies to be seen. Its total bolometric luminosity is 660 times solar, mostly in the ultraviolet, thus suggesting a radius that is 5.5 times that of the Sun and a mass that is slightly more than 4 times solar. Maia is one of the stars in the Maia Nebula (also known as NGC 1432), a bright emission or reflection nebula within the Pleiades star cluster. Maia was thought to be a variable star by astronomer Otto Struve. A class of stars known as Maia variables was proposed, which included Gamma Ursae Minoris, but Maia and some others in the class have since been found to be stable. Maia was the oldest of seven beautiful sisters known as the Pleiades. She was raped by Zeus, thereby
    6.83
    6 votes
    9
    HD 179949

    HD 179949

    HD 179949 is a 6th magnitude star in the constellation of Sagittarius. It is a yellow-white dwarf (spectral class F8 V), a type of star hotter and more luminous than our Sun. The star is located at 88 light years from Earth and might be visible under exceptionally good conditions to an experienced observer without technical aid; usually binoculars are needed. The only known planet orbiting HD 179949 is HD 179949 b.
    8.75
    4 votes
    10
    Mars

    Mars

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Phobos
    Mars is the fourth planet from the Sun and the second smallest planet in the Solar System. Named after the Roman god of war, it is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the highest known mountain within the Solar System, and of Valles Marineris, one of the largest canyons. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Martian trojan asteroid. Until the first successful flyby of Mars occurred in 1965 by Mariner 4, many speculated about the presence of liquid water on the planet's surface. This was based on observed periodic variations in light and dark
    8.75
    4 votes
    11
    Alpha Pavonis

    Alpha Pavonis

    Alpha Pavonis (α Pav) is a star in the southern constellation Pavo, near the shared border with the Telescopium constellation. It is also known by the name Peacock, which was assigned by Her Majesty's Nautical Almanac Office in the late 1930s during the creation of the Air Almanac, a navigational almanac for the Royal Air Force. Of the fifty-seven stars included in the new almanac, two had no classical names: Epsilon Carinae and Alpha Pavonis. The RAF insisted that all of the stars must have names, so new names were invented. Alpha Pavonis was named "Peacock" ('pavo' is Latin for 'peacock') whilst Epsilon Carinae was called "Avior". At an apparent magnitude of 1.94, this is the brightest star in Pavo. Based upon parallax measurements, this star is about 179 light-years (55 parsecs) distant from the Earth. It has an estimated six times the Sun's mass and 5–6 times the Sun's radius, but 2,200 times the luminosity of the Sun. However, Tetzlaff et al (2011) suggest a much higher mass of 9 times the mass of the Sun. The effective temperature of the photosphere is 18,000 K, which gives the star a blue-white hue. A stellar classification of B2 IV suggests it is a subgiant star that has
    6.50
    6 votes
    12
    Altair

    Altair

    Altair (Alpha Aquilae, Alpha Aql, α Aquilae, α Aql, Atair) is the brightest star in the constellation Aquila and the twelfth brightest star in the night sky. It is an A-type main sequence star with an apparent visual magnitude of 0.77 and is one of the vertices of the Summer Triangle (the other two vertices are marked by Deneb and Vega). Altair rotates rapidly, with a velocity at the equator of approximately 286 km/s. A study with the Palomar Testbed Interferometer revealed that Altair is not spherical, but is flattened at the poles due to its high rate of rotation. Other interferometric studies with multiple telescopes, operating in the infrared, have imaged and confirmed this phenomenon. Altair is located 16.7 light-years (5.13 parsecs) from Earth and is one of the closest stars visible to the naked eye. Along with Beta Aquilae and Gamma Aquilae, it forms the well-known line of stars sometimes referred to as the Family of Aquila or Shaft of Aquila. Altair is a type-A main sequence star with approximately 1.8 times the mass of the Sun and 11 times its luminosity. Altair possesses an extremely rapid rate of rotation; it has a rotational period of approximately 9 hours. For
    6.50
    6 votes
    13
    52 Europa

    52 Europa

    • Orbits: Sun
    52 Europa is one of the larger asteroids in the asteroid belt, having a diameter of 300 km. It was discovered on February 4, 1858, by Hermann Goldschmidt from his balcony in Paris. It is named after Europa, one of Zeus's conquests in Greek mythology, a name it shares with Jupiter's moon Europa. Europa is approximately the seventh largest asteroid by volume. However, it has a low density (i.e. is highly porous), presumably through having suffered a particularly severe collision. In 2001, Michalak estimated Europa to have a mass of (5.2±1.8)×10 kg. In 2007, James Baer and Steven R. Chesley estimated Europa to have a mass of (1.9±0.4)×10 kg. A more recent estimate by Baer suggests it has a mass of 1.65×10 kg. Europa is a very dark carbonaceous C-type, and is the fourth largest of this group. Spectroscopic studies have found evidence of olivines and pyroxenes on the surface, and there is some indication that there may be compositional differences between different regions It orbits close to the Hygiea asteroid family, but is not a member. Lightcurve data for Europa has been particularly tricky to interpret, so much so that for a long time its period of rotation was in dispute (ranging
    7.40
    5 votes
    14
    Mu Cephei

    Mu Cephei

    Mu Cephei (μ Cep, μ Cephei), also known as Herschel's Garnet Star, is a red supergiant star in the constellation Cepheus. It is one of the largest and most luminous stars known in the Milky Way. It appears garnet red and is given the spectral class of M2 Ia. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. The deep red color of Mu Cephei was noted by William Herschel, who described it as "a very fine deep garnet colour, such as the periodical star ο Ceti", and it is thus commonly known as Herschel's "Garnet Star". Giuseppe Piazzi called it Garnet sidus in his catalogue. An alternative name, Erakis, used in Antonín Bečvář's star catalogue, is probably due to confusion with Mu Draconis, which was previously called al-Rāqis [arˈraːqis] in Arabic. In 1848, English astronomer John Russell Hind discovered that it was variable. This variability was quickly confirmed by German astronomer Friedrich Wilhelm Argelander. Almost continual records of the star's variability have been maintained since 1881. A very luminous red supergiant, Mu Cephei is one of the largest stars visible to the naked eye, and in the entire
    7.40
    5 votes
    15
    Neptune

    Neptune

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Naiad
    Neptune is the eighth and farthest planet from the Sun in the Solar System. It is the fourth-largest planet by diameter and the third-largest by mass. Neptune is 17 times the mass of Earth and is somewhat more massive than its near-twin Uranus, which is 15 times the mass of Earth but not as dense. On average, Neptune orbits the Sun at a distance of 30.1 AU, approximately 30 times the Earth–Sun distance. Named for the Roman god of the sea, its astronomical symbol is ♆, a stylised version of the god Neptune's trident. Neptune was the first planet found by mathematical prediction rather than by empirical observation. Unexpected changes in the orbit of Uranus led Alexis Bouvard to deduce that its orbit was subject to gravitational perturbation by an unknown planet. Neptune was subsequently observed on 23 September 1846 by Johann Galle within a degree of the position predicted by Urbain Le Verrier, and its largest moon, Triton, was discovered shortly thereafter, though none of the planet's remaining 12 moons were located telescopically until the 20th century. Neptune has been visited by only one spacecraft, Voyager 2, which flew by the planet on 25 August 1989. Neptune is similar in
    7.40
    5 votes
    16
    Achernar

    Achernar

    Achernar (α Eri, α Eridani, Alpha Eridani), sometimes spelled Achenar, is the brightest star in the constellation Eridanus and the ninth-brightest star in the night sky. Of the top ten apparent brightest stars (excluding our Sun)—Sirius, Canopus, Alpha Centauri, Arcturus, Vega, Capella, Rigel, Procyon, Achernar and Betelgeuse—Achernar is the hottest and bluest. It lies at the southern tip of the constellation. Achernar is a bright, blue star with about six to eight solar masses. As determined by the Hipparcos astrometry satellite, it is approximately 139 light-years (43 pc) away. It is a main sequence star with a stellar classification of B6 Vep, but is about 3,150 times more luminous than the Sun. Achernar is in the deep southern sky and never rises above the horizon beyond 33°N, roughly the latitude of Dallas, Texas. Achernar is best seen from the southern hemisphere in November; it is circumpolar below 33°S. Until about March 2000, Achernar and Fomalhaut were the two first-magnitude stars furthest in angular distance from any other first-magnitude star in the celestial sphere. Antares, in the constellation of Scorpius, is now the most isolated first-magnitude star, although
    6.33
    6 votes
    17
    Epsilon Scuti

    Epsilon Scuti

    Epsilon Scuti (ε Sct, ε Scuti) is a star system in the constellation Scutum. It is approximately 523 light years from Earth. The primary component, Epsilon Scuti A, is a yellow G-type bright giant with an apparent magnitude of +4.88. It has at least three faint companions, two 14th magnitude stars, B and D, separated from the primary by 13.6 and 15.4 arcseconds respectively, and the 13th magnitude C, which is 38 arcseconds away. Epsilon Scuti was a latter designation of 3 Aquilae.
    6.33
    6 votes
    18
    Zeta Arae

    Zeta Arae

    Zeta Arae (ζ Ara, ζ Arae) is a star in the southern constellation Ara. It is sometimes is called by the name Tseen Yin, together with δ Arae. The apparent visual magnitude of this star is 3.1, which can be seen from suburban skies in the southern hemisphere. From the parallax measurements, it is located at a distance of 490 light-years (150 parsecs) from Earth. The spectrum of this star matches a stellar classification of K3 III. The luminosity class of 'III' indicates this is a giant star that has exhausted the hydrogen at its core and evolved away from the main sequence. It is radiating energy from its outer atmosphere at an effective temperature of 4,350 K, which is what gives it the orange hue of a K-type star. This star displays an excess of infrared emission that may indicate circumstellar matter. In Chinese, 杵 (Guī), meaning Tortoise, refers to an asterism consisting of ζ Arae, ε Arae, γ Arae, δ Arae and η Arae. Consequently, ζ Arae itself is known as 龜五 (Guī wǔ, English: the Fifth Star of Tortoise.)
    9.67
    3 votes
    19
    Crab Pulsar

    Crab Pulsar

    The Crab Pulsar (PSR B0531+21) is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054. Discovered in 1968, the pulsar was the first to be connected with a supernova remnant. The optical pulsar is roughly 25 km in diameter and the pulsar "beams" rotate once every 33 milliseconds, or 30 times each second. The outflowing relativistic wind from the neutron star generates synchrotron emission, which produces the bulk of the emission from the nebula, seen from radio waves through to gamma rays. The most dynamic feature in the inner part of the nebula is the point where the pulsar's equatorial wind slams into the surrounding nebula, forming a termination shock. The shape and position of this feature shifts rapidly, with the equatorial wind appearing as a series of wisp-like features that steepen, brighten, then fade as they move away from the pulsar into the main body of the nebula. The period of the pulsar's rotation is slowing by 38 nanoseconds per day due to the large amounts of energy carried away in the pulsar wind. The Crab Nebula is often used as a calibration
    8.25
    4 votes
    20
    Epsilon Boötis

    Epsilon Boötis

    Epsilon Boötis (ε Boo, ε Boötis) is a double star in the northern constellation of Boötes. It has the traditional names Izar and Pulcherrima. The star system can be viewed with the unaided eye at night, but resolving the pair with a small telescope is challenging; an aperture of 76 mm (3.0 in) or greater is required. Epsilon Boötis consists of a pair of stars with an angular separation of 2.852 ± 0.014 arcseconds at a position angle of 342.°9 ± 0.°3. The brighter component (A) has an apparent visual magnitude of 2.37, making it readily visible to the naked eye at night. The fainter component (B) is at magnitude 5.12, which by itself would also be visible to the naked eye. Parallax measurements from the Hipparcos astrometry satellite put the system at a distance of about 203 light-years (62 parsecs) from the Earth. This means the pair has a projected separation of 185 Astronomical Units and they orbit each other with a period of at least 1,000 years. The brighter member has a stellar classification of K0 II-III, which means it is a fairly late-stage star well into its stellar evolution, having already exhausted its supply of hydrogen fuel at the core. With more than four times the
    8.25
    4 votes
    21
    Lambda Aquarii

    Lambda Aquarii

    Lambda Aquarii (λ Aqr, λ Aquarii) is the Bayer designation for a star in the equatorial constellation of Aquarius. It has the obscure traditional names Hydor and Ekkhysis, from the ancient Greek ὕδωρ "water" and ἔκχυσις "outpouring". The apparent visual magnitude of this star is 3.722, which is bright enough to be visible with the naked eye. It is roughly 390 light-years (120 pc) from Earth. In Chinese, 壘壁陣 (Lěi Bì Zhèn), meaning Line of Ramparts, refers to an asterism consisting of λ Aquarii, κ Capricorni, ε Capricorni, γ Capricorni, δ Capricorni, ι Aquarii, σ Aquarii, φ Aquarii, 27 Piscium, 29 Piscium, 33 Piscium and 30 Piscium. Consequently, λ Aquarii itself is known as 壘壁陣七 (Lěi Bì Zhèn qī, English: the Seventh Star of Line of Ramparts.) Lambda Aquarii is a red giant star with a stellar classification of M2.5 III. It is a semiregular variable star star with pulsation periods of 24.5, 32.0, and 49.5 days. This star is on the asymptotic giant branch and is generating energy through the nuclear fusion of hydrogen and helium along concentric shells surrounding an inert core of carbon and oxygen.
    8.25
    4 votes
    22
    Epsilon Aurigae

    Epsilon Aurigae

    Epsilon Aurigae (ε Aur, ε Aurigae) is the Bayer designation for a star in the northern constellation of Auriga. It is traditionally known as Almaaz, Haldus, or Al Anz. Epsilon Aurigae is an unusual eclipsing binary system comprising an F0 supergiant and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a binary system of two small B-type stars. About every 27 years, Epsilon Aurigae's brightness drops from an apparent visual magnitude of +2.92 to +3.83. This dimming lasts 640–730 days. In addition to this eclipse, the system also has a low amplitude pulsation with a non-consistent period of around 66 days. The distance to the system is still a subject of debate, but modern estimates place it approximately 2,000 light years from Earth. Epsilon Aurigae was first suspected to be a variable star when German astronomer Johann Fritsch observed it in 1821. Later observations by Eduard Heis and Friedrich Wilhelm Argelander reinforced Fritsch's initial suspicions and attracted attention to the star. Hans Ludendorff, however, was the first to study it in great detail. His work revealed that the system was an eclipsing binary variable, a star
    9.33
    3 votes
    23
    Delta Scorpii

    Delta Scorpii

    Delta Scorpii (δ Sco, δ Scorpii) is a star in the constellation Scorpius. It has the traditional name Dschubba (or Dzuba, from Arabic jabhat, "forehead" (of the scorpion) or also Iclarcrau or Iclarkrav. Because Delta Scorpii is near the ecliptic it is occasionally occulted by the Moon, or (extremely rarely) by planets. Delta Scorpii is a proper motion member of the Upper Scorpius subgroup of the Scorpius-Centaurus OB association, the nearest such co-moving association of massive stars to the Sun.. The Upper Scorpius subgroup contains thousands of young stars with mean age 11 million years at average distance of 470 light years (145 parsecs). A recent analysis of the HR diagram position for Delta Scorpii estimates its effective temperature to be 27,400 Kelvin with a luminosity of 38,000 Suns, consistent with an isochronal age of 9-10 million years and an estimated mass of 14.6-14.9 solar masses. In June 2000, Delta Scorpii was observed by Sebastian Otero to be 0.1 magnitudes brighter than normal. Its brightness has varied since then and has reached as high as magnitude 1.65, altering the familiar appearance of Scorpius. Spectra taken after the outburst began have shown that the star
    8.00
    4 votes
    24
    Theta Andromedae

    Theta Andromedae

    Theta Andromedae (θ And, θ Andromedae) is the Bayer designation for a binary star in the constellation Andromeda. It is approximately 310 light-years (95 parsecs) from Earth, with a visual magnitude of 4.6. On the Bortle Dark-Sky Scale, this makes it visible to the naked eye from outside urban regions. Theta Andromedae is a white A-type main sequence dwarf with an apparent magnitude of +4.61. It appears to be a binary star with a massive, possibly A-type secondary orbiting at a distance of around 1 astronomical unit. A fainter companion is separated from Theta Andromedae by 0.06 arcseconds. In Chinese, 天廄 (Tiān Jiù), meaning Celestial Stable, refers to an asterism consisting of θ Andromedae, ρ Andromedae and σ Andromedae. Consequently, θ Andromedae itself is known as 天廄一 (Tiān Jiù yī, English: the First Star of Celestial Stable.)
    6.00
    6 votes
    25
    61 Virginis

    61 Virginis

    61 Virginis (abbreviated 61 Vir) is a G5V class star slightly less massive than the Sun (G2V), located about 27.8 light-years away in the constellation of Virgo. The composition of this star is nearly identical to the Sun and there is only a low level of activity in the stellar chromosphere. This star is rotating once every 29 days at the equator. The space velocity components of this star are U = –37.9, V = –35.3 and W = –24.7 km/s. 61 Vir is orbiting through the Milky Way galaxy at a distance of 6.9 kpc from the core, with an eccentricity of 0.15. It is believed to be a disk star with an estimated age of more than six billion years. 61 Virginis (G5V) is the first well established main sequence yellow dwarf star very similar to the Sun with a potential Super-Earth, though COROT-7 (a borderline orange dwarf) is arguably the first. There was some evidence that it may have a jovian planet, but it seemed not to have a nearby massive companion. A subsequent study also failed to find the large substellar companion (with 20 to 80 times the mass of Jupiter) or a Jupiter-class planet, so it was a good candidate for possessing a family of terrestrial planets, with an orbit slightly smaller
    6.80
    5 votes
    26
    6489 Golevka

    6489 Golevka

    • Orbits: Sun
    6489 Golevka is an Apollo, Mars-crosser and Alinda asteroid, discovered in 1991 by Eleanor F. Helin. Its name has a complicated origin. In 1995, Golevka was studied simultaneously by three radar observatories across the world: Goldstone in California, Yevpatoria RT-70 radio telescope in Ukraine (Yevpatoria is sometimes romanized as Evpatoria) and Kashima in Japan. 'Golevka' comes from the first few letters of each observatory's name; it was proposed by the discoverer following a suggestion by Alexander L. Zaitsev. Golevka is a small object, measuring 0.6 × 1.4 km. The radar observations revealed that it has a very strange, angular shape that looks different depending on the direction. In 2003 the Yarkovsky effect was first observed at work by high-precision radar observations of Golevka. Between 1991 and 2003, the small force of the Yarkovsky Effect caused a shift of 15 kilometers (9.4 miles) from what would be expected based on only gravitational interactions. This helped evaluate the asteroid's bulk density (2.7 ± 0.5 g/cm³) and mass (2.10×10 kg). It approaches Earth to 0.05 AU (7,500,000 km; 4,600,000 mi) in 2046, 0.10 AU in 2069, and 0.11 AU in 2092. Golevka's collision
    6.80
    5 votes
    27
    Beta Cephei

    Beta Cephei

    Beta Cephei (β Cep, β Cephei) is a third magnitude star in the constellation Cepheus. It has the traditional name Alfirk (Arabic الفرقة al-firqah), meaning "The Flock" (referring to a flock of sheep) This star, along with α Cep (Alderamin) and η Cep (Alkidr), were Al Kawākib al Firḳ (الكوكب الفرق), meaning "the Stars of The Flock" by Ulug Beg. Beta Cephei is the prototype of the Beta Cephei variable stars. Like the star Epsilon Draconis in the constellation of Draco, Alfirk is visible primarily in the northern hemisphere, given its extreme northern declination of 70 degrees and 34 minutes. The star is nevertheless visible to most observers throughout the world reaching as far south as cities like Harare in Zimbabwe, Santa Cruz de la Sierra in Bolivia or other settlements north ± 19° South latitude. The star is circumpolar throughout all of Europe, northern Asia, and North American cities as far south as Guadalajara in west central Mexico. All other locations around the globe having a latitude greater than ± 20° North will notice that the star is always visible in the night sky. Because Beta Cephei is a faint third magnitude star, it may be difficult to identify in most light
    6.80
    5 votes
    28
    (15788) 1993 SB

    (15788) 1993 SB

    • Orbits: Sun
    (15788) 1993 SB is a trans-Neptunian object of the plutino class. Apart from Pluto, it was one of the first such objects discovered (beaten by two days by 1993 RO and by one day by 1993 RP), and the first to have an orbit calculated well enough to receive a number. The discovery was made in 1993 at the La Palma Observatory with the Isaac Newton Telescope. Very little is known about the object. Even the diameter estimate of ~130 km is based on an assumed albedo of 0.09.
    9.00
    3 votes
    29
    Beta Camelopardalis

    Beta Camelopardalis

    Beta Camelopardalis (β Cam / β Camelopardalis) is a star in the constellation Camelopardalis. β Camelopardalis is a yellow G-type supergiant with an apparent magnitude of +4.03. This is a double star, with components of magnitudes 4.0 and 7.4. It is approximately 1000 light years from Earth.
    9.00
    3 votes
    30
    Nu Caeli

    Nu Caeli

    Nu Caeli (ν Cae, ν Caeli), also known as, HD 30985, HR 1557 is a star in the constellation Caelum. ν Caeli is a yellow-white F-type main sequence dwarf with an apparent magnitude of +6.06. It is approximately 171 light years from Earth.
    7.75
    4 votes
    31
    Zeta Apodis

    Zeta Apodis

    Zeta Apodis (ζ Aps, ζ Apodis) is the Bayer designation for a star in the southern constellation of Apus. It has an apparent visual magnitude of +4.78, which is bright enough to allow it to be seen with the naked eye. The distance to this star is known from parallax measurements to be around 297 light-years (91 parsecs). The spectrum of Zeta Apodis matches a stellar classification of K2 III, with the luminosity class of III indicating it is an evolved giant star. The measured angular diameter of this star, after correction for limb darkening, is 2.06 ± 0.02 mas. At the estimated distance of Eta Draconis, this yields a physical size of about 11 times the radius of the Sun. The outer atmosphere has an effective temperature of 4,388 K, which gives it the orange-hued glow of a K-type star. In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of ζ Apodis, ι Apodis, β Apodis, γ Apodis, δ Octantis, δ Apodis, η Apodis, α Apodis and ε Apodis. Consequently, ζ Apodis itself is known as 異雀一 (Yì Què yī, English: the First Star of Exotic Bird.)
    7.75
    4 votes
    32
    3200 Phaethon

    3200 Phaethon

    • Orbits: Sun
    3200 Phaethon ( /ˈfeɪ.əθɒn/ FAY-ə-thon, sometimes incorrectly spelled Phaeton) is an asteroid with an unusual orbit that brings it closer to the Sun than any other named asteroid (though there are several unnamed asteroids, including three numbered ones, with smaller perihelia, e.g. (137924) 2000 BD19). For this reason, it was named after the Greek myth of Phaëton, son of the sun god Helios. It is 5.10 km in mean diameter. Phaethon was the first asteroid to be discovered using images from a spacecraft. Simon F. Green and John K. Davies discovered it in images from October 11, 1983 while searching Infrared Astronomical Satellite (IRAS) data for moving objects. It was announced on October 14 in IAUC 3878 along with optical confirmation by Charles T. Kowal, who reported it to be asteroidal in appearance. Its provisional designation was 1983 TB. It is categorized as an Apollo asteroid (because its semi-major axis is greater than that of the Earth's and its perihelion is less than 1.017 astronomical units. It is also suspected to be a member of the Pallas family of asteroids. Phaethon's most remarkable distinction is that it approaches the Sun closer than any other named asteroid: its
    6.60
    5 votes
    33
    Delta Canis Majoris

    Delta Canis Majoris

    Delta Canis Majoris (δ CMa, δ Canis Majoris) is a star in the constellation Canis Major. It has the traditional name Wezen or Wesen. It is a yellow-white F-type supergiant with an apparent magnitude of +1.83. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. δ Canis Majoris is the third brightest star in the constellation after Sirius and Adhara, with an apparent magnitude of +1.83, and is a white or yellow-white in colour. Lying about 10 degrees south southeast of Sirius, it only rises to about 11 degrees above the horizon at the latitude of the United Kingdom. The open cluster NGC 2354 is located only 1.3 degrees east of Delta Canis Majoris. As with the rest of Canis Major, Wezen is most visible in winter skies in the northern hemisphere, and summer skies in the southern. It theoretically makes up the Great Dog's hind quarter. The traditional name, Wezen, is derived from the medieval Arabic وزن al-wazn, which means "weight" in modern Arabic. The name was for one of a pair of stars, the other being Hadar, which has now come to refer to Beta Centauri. It is unclear whether the pair of stars was originally Alpha
    6.60
    5 votes
    34
    Beta Apodis

    Beta Apodis

    Beta Apodis (β Aps, β Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. It is located approximately 158 light-years (48 parsecs) from Earth, as determined by parallax measurements. The apparent visual magnitude of this star is +4.24, which is bright enough to be seen with the naked eye The spectrum of this star matches the characteristics of a K0 III, which, according to models of stellar evolution, indicates that it is in the giant star stage, having exhausted the supply of hydrogen at its core. The measured angular diameter of this star is 2.09 ± 0.11 mas. At the estimated distance of this star, this yields a physical size of about 11 times the radius of the Sun. The expanded outer atmosphere of Beta Apodis has an effective temperature of about 4,900 K. This heat is causing it to glow with the characteristic orange hue of a K-type star. In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of β Apodis, ζ Apodis, ι Apodis, γ Apodis, δ Octantis, δ Apodis, η Apodis, α Apodis and ε Apodis. Consequently, β Apodis itself
    7.50
    4 votes
    35
    Epsilon Lyrae

    Epsilon Lyrae

    Epsilon Lyrae (ε Lyr, ε Lyrae), also known as the Double Double, is a multiple star system approximately 162 light-years away in the constellation of Lyra. The widest two components of the system are easily separated when viewed through binoculars, or even with the naked eye under excellent conditions. The northern star is called ε and the southern one is called ε; they both lie around 162 light years from Earth and orbit each other. When viewed at higher magnifications, both stars of the binary can be further split into binaries; that is, the system contains two binary stars orbiting each other. Being able to view the components of each is a common benchmark for the resolving power of telescopes, since the individual doubles are so close together: the stars of ε were 2.35 arc-seconds apart in 2006, those of ε were separated by about the same amount in that year. Since the first high-precision measurements of their orbit in the 1980s, both binaries have moved only a few degrees in position angle. The component stars of ε have magnitudes of 4.7 and 6.2 separated by 2.6" and have an orbital period that can only be crudely estimated at 1200 years, which places them at roughly 140 AU
    7.50
    4 votes
    36
    Epsilon Reticuli

    Epsilon Reticuli

    Epsilon Reticuli (Epsilon Ret, ε Reticuli, ε Ret) is a double star approximately 59 light-years away in the constellation of Reticulum. The primary component is an orange subgiant star, while the secondary is a white dwarf star. The two stars share a common motion through space and hence most likely form a binary star system. The brighter star should be easily visible without optical aid under dark skies in the southern hemisphere. In 2000, an extrasolar planet was confirmed to be orbiting the primary star in the system. The primary component is a subgiant star with a stellar classification of K2 IV. The fusing hydrogen in its core is coming to an end and it is in the process of expanding as a red giant. (The NStars project gave it a classification of K2 III, which would make it a giant star.) The secondary component is a white dwarf star located at a separation of at least 240 AU from the primary. It has a surface temperature between 9000 and 17000 K. On December 11, 2000, a team of astronomers announced the discovery of a planet Epsilon Reticuli b. With a minimum mass of 1.17 that of Jupiter and a similar radius, the planet moves around Epsilon Reticuli with an average separation
    7.50
    4 votes
    37
    Xi Ursae Majoris

    Xi Ursae Majoris

    Xi Ursae Majoris (Xi UMa, ξ Ursae Majoris, ξ UMa) is a star system in the constellation Ursa Major. On May 2, 1780, Sir William Herschel discovered that this was a binary star system, making it the first such system ever discovered. It was the first visual double star for which an orbit was calculated, when it was computed by Félix Savary in 1828. The two components are yellow G-type main-sequence stars. The brighter component, Xi Ursae Majoris A, has a mean apparent magnitude of +4.41. It is classified as an RS Canum Venaticorum type variable star and its brightness varies by 0.01 magnitudes. The companion star, Xi Ursae Majoris B has an apparent magnitude of +4.87. The orbital period of the two stars is 59.84 years, and they are currently separated by 1.2 arcseconds, or at least 10 AUs. Each component of this double star is itself a spectroscopic binary. B's binary companion, denoted Xi Ursae Majoris Bb, is unresolved, but the binary star is known to have an orbital period of 3.98 days. The masses of both A and B's companions (Ab and Bb) (deduced by the sum total mass of the system minus the likely masses of Aa and Ba determined by their class) indicate that they are probably MV
    7.50
    4 votes
    38
    142 Polana

    142 Polana

    • Orbits: Sun
    142 Polana is a very dark main belt asteroid. It was discovered by Johann Palisa on January 28, 1875, and named after the city of Pola (now Pula, Croatia), home of the Austrian Naval Observatory where he made the discovery. It is a major member of the eponymously-named Polana family, which is a subgroup of the Nysa family. The asteroid has an estimated diameter of about 55.3 km and a low albedo of 0.045. It is orbiting at a distance of 2.419 times the separation of the Earth from the Sun, with an orbital period of 3.76 years and an eccentricity of 0.14. In the Tholen classification scheme, Polana is a primitive carbonaceous asteroid of type F, which is a subdivision of more common C-type. Under the SMASS classification taxonomy, Polana is listed as a B-type asteroid; a group that combines both the Tholen B and F types. The spectrum of this object suggests the presence of magnetite (Fe3O4), which gives it the spectrally-blue coloration that is a characteristic of this SMASS class. Polana is in a 1:2 orbital resonance with Mars, meaning that Polana orbits the Sun once for every two orbits that Mars completes. This resonance helps protect the asteroid from orbital erosion: the orbital
    8.67
    3 votes
    39
    8405 Asbolus

    8405 Asbolus

    • Orbits: Sun
    8405 Asbolus ( /ˈæzbɵləs/; from Greek: Άσβολος) is a centaur orbiting between the orbits of Jupiter and Neptune. It was discovered by James V. Scotti and Robert Jedicke of Spacewatch at Kitt Peak Observatory on April 5, 1995. It is named after Asbolus (Greek for sooty), a centaur in Greek mythology. Its provisional designation was 1995 GO. Observations with the Spitzer Space Telescope in 2007 resulted in a diameter calculation of about 84 ± 8 km. No resolved images of it have ever been made but, in 1998, spectral analysis of its composition by the Hubble Space Telescope revealed a fresh impact crater on its surface, less than 10 million years old. Centaurs are dark in colour, because their icy surfaces have darkened after long exposure to solar radiation and the solar wind. However, fresh craters excavate more reflective ice from below the surface, and that is what Hubble has detected on Asbolus. Centaurs have short dynamical lifetimes due to perturbations by the giant planets. Asbolus is estimated to have an orbital half-life of about 860 kiloannum. Asbolus is currently classified as a SN centaur since Saturn is considered to control the perihelion and Neptune controls the
    8.67
    3 votes
    40
    Rho Cassiopeiae

    Rho Cassiopeiae

    Rho Cassiopeiae ( /ˌroʊ kæsiəˈpiː.iː/; ρ Cas, ρ Cassiopeiae) is a yellow hypergiant star in the constellation Cassiopeia. It is about 11,650 light-years (3,570 pc) away from Earth, yet can still be seen by the naked eye (in the Northern Hemisphere only), as it is 100,000 times as luminous as the Sun. On average, it has an absolute magnitude of −7.5, making it one of the most luminous stars known. Its surface diameter measures 450 times that of the Sun, or approximately 630,000,000 kilometers. Being a yellow hypergiant, it is one of the rarest types of stars, one of only seven in the Milky Way that are currently known, though it is not the only one in its constellation, which also includes V509 Cassiopeiae. Rho Cassiopeiae is a single star, and is categorized as a semiregular variable. The Bayer designation for this star was established in 1603 as part of the Uranometria, a star catalog produced by Johann Bayer. The star catalog by John Flamsteed published in 1712, which orders the stars in each constellation by their right ascension, gave this star the Flamsteed designation 7 Cassiopeiae. Rho Cassiopeiae is somewhat unstable in its luminosity. Its apparent magnitude is currently
    8.67
    3 votes
    41
    Gamma Capricorni

    Gamma Capricorni

    Gamma Capricorni (γ Cap, γ Capricorni) is a giant star in the constellation Capricornus. It has the traditional name Nashira, which comes from the Arabic سعد ناشرة - sa'd nashirah for "the lucky one" or "bearer of good news". In Chinese, 壘壁陣 (Lěi Bì Zhèn), meaning Line of Ramparts, refers to an asterism consisting of γ Capricorni, κ Capricorni, ε Capricorni, δ Capricorni, ι Aquarii, σ Aquarii, λ Aquarii, φ Aquarii, 27 Piscium, 29 Piscium, 33 Piscium and 30 Piscium. Consequently, γ Capricorni itself is known as 壘壁陣三 (Lěi Bì Zhèn sān, English: the Third Star of Line of Ramparts.) Because it is near the ecliptic, γ Capricorni can be occulted by the Moon, and (rarely) by planets. γ Capricorni is a blue-white A-type (A7III) giant star with a mean apparent magnitude of +3.69. It is approximately 139 light years from Earth. It is classified as an Alpha2 Canum Venaticorum type variable star and its brightness varies by 0.03 magnitudes. Nashira (AK-85) is once of United States navy ship. ukdj FGJYJ68J9HR[6OIJUYHITJYHJYT9JIHY6[IOJK4]H90W64JT0966[9UJYK
    10.00
    2 votes
    42
    Theta Cassiopeiae

    Theta Cassiopeiae

    Theta Cassiopeiae (θ Cas, θ Cassiopeiae) is a star in the constellation Cassiopeia. It has the traditional name Marfark or Marfak, which it shares with μ Cassiopeiae, and the name was from Al Marfik or Al Mirfaq (المرفق), meaning "the elbow". In Chinese, 閣道 (Gé Dào), meaning Flying Corridor, refers to an asterism consisting of θ Cassiopeiae, ι Cassiopeiae, ε Cassiopeiae, δ Cassiopeiae, ν Cassiopeiae and ο Cassiopeiae. Consequently, θ Cassiopeiae itself is known as 閣道四 (Gé Dào sì, English: the Fourth Star of Flying Corridor.) θ Cassiopeiae is a white A-type main sequence dwarf with an apparent magnitude of +4.34. It is approximately 137 light years from Earth.
    10.00
    2 votes
    43
    BD +20 307

    BD +20 307

    BD +20°307 is a close binary star system approximately 300 light-years away in the constellation Aries. The system is surrounded by a dusty ring. The dust that orbits around several hundred main-sequence stars is cold and comes from a Kuiper-belt analogous region. In our solar system the on-going collisions between asteroids generate a tenuous cloud of dust known as the zodiacal light. When our solar system was young such collisions were more common and the rate of dust production was probably many times higher. Zodiacal dust around stars much younger than the Sun has been rarely found. Only a few main-sequence stars have revealed warm (>120 K) zodiacal dust. An exceptionally large amount of warm, small, silicate dust particles around the solar-type star BD +20°307 (HIP 8920, SAO 75016) has been reported. The composition, quantity and temperature of the dust may be explained by recent, frequent or huge collisions between asteroids or other planetesimals whose orbits are being perturbed by a nearby planet. Both stars of the close binary are considered to be Solar-type stars that are slightly more massive than the Sun. The two stars differ in effective temperature by only ~250 K and
    6.40
    5 votes
    44
    LHS 292

    LHS 292

    LHS 292 is a red dwarf star in the constellation Sextans. This star is far too faint to be seen with the unaided eye and requires a large amateur telescope to be seen visually. It lies relatively close to our Sun at a distance of about 14.8 light years. It is a flare star, which means it can suddenly increase in brightness for short periods of time. It has the space velocity components [U, V, W] = [28, −16, −14] km/s.
    6.40
    5 votes
    45
    Ross 614

    Ross 614

    Ross 614 (V577 Monocerotis) is a red dwarf UV Cetiflare star and it is the primary member of a nearby binary star system in the constellation of Monoceros. This star has an magnitude of about 11, making it invisible to the unaided eye even though it is one of the stars nearest to the sun. This system is among the closest to our Sun at an estimated distance of about 13.3 light years. Because this star is so close to the Earth it is often the subject of study, hence the large number of designations by which it is known. This binary star system consists of two closely spaced low-mass red dwarf M-type stars. The secondary star is a dim magnitude 14 lost in the glare of the nearby primary star. The most recent determination of the system orbital elements comes from a study by George Gatewood using older sources along with data from the Hipparcos satellite. This study yielded an orbital period of about 16.6 years and a semi-major axis separation of about 1.1 arc seconds. The primary star was discovered in 1927 by F. E. Ross using the 40 in (100 cm) refractor telescope at the Yerkes Observatory. He noticed the high proper motion of this dim 11th magnitude star in his second-epoch plates
    6.40
    5 votes
    46
    1001 Gaussia

    1001 Gaussia

    • Orbits: Sun
    1001 Gaussia is a main-belt asteroid orbiting the Sun. Initially it received the designation 1923 OA. Later it was named after the mathematician Carl F. Gauss. It has a mean visual magnitude of 9.77. Observation of the change in magnitude of this minor planet suggests it has a rotation period of 9.127 ± 0.002 h. Over this period it undergoes variation in magnitude of 0.16.
    7.25
    4 votes
    47
    Comet Morehouse

    Comet Morehouse

    Comet Morehouse (modern formal designation: C/1908 R1) was a bright, non-periodic comet discovered by US astronomer Daniel Walter Morehouse and first observed on September 1, 1908. It was unusual in the rapid variations seen in the structure of its tail. At times, the tail seemed to split into up to six separate tails; at others, the tail appeared completely detached from the head of the comet. The tail was further unusual in that it formed while the comet was still 2 AU away from the Sun (where distances of 1.5 AU are more usual), and that there was a high concentration of the CO ion in its spectrum. As is typical for comets fresh from the Oort Cloud, its orbital solution is more or less parabolic; if its orbit is in fact closed, it will likely not return for millions of years.
    7.25
    4 votes
    48
    Nu Arietis

    Nu Arietis

    Nu Arietis (ν Ari, ν Arietis) is the Bayer designation for a star in the constellation Aries. Nu Arietis is a white-hued A-type main sequence star with an apparent magnitude of +5.45. It is approximately 336 light years from Earth.
    7.25
    4 votes
    49
    46P/Wirtanen

    46P/Wirtanen

    46P/Wirtanen is a small short-periodic comet with a current orbital period of 5.4 years. It was the original target for close investigation by the Rosetta spacecraft, planned by the European Space Agency. It belongs to the Jupiter family of comets, all of which have aphelia between 5 and 6 AU. Its diameter is estimated at 1.2 kilometres (0.75 mi). The comet is the target for the proposed 2016 Comet Hopper mission. 46P/Wirtanen was discovered photographically on January 17, 1948, by the American astronomer Carl A. Wirtanen. The plate was exposed on January 15 during a stellar proper motion survey for the Lick Observatory. Due to a limited number of initial observations, it took more than a year to recognize this object as a short-period comet. On 16 December 2018 the comet will pass 0.0777 AU (11,620,000 km; 7,220,000 mi) from Earth. The Comet Hopper is a proposed lander to NASA's Discovery Program that, if selected, would orbit and land multiple times on Comet Wirtanen as the comet approaches the Sun. The Comet Hopper mission has three primary science goals over the 7.3 years of its nominal lifetime. At roughly 4.5 AU the spacecraft will rendezvous with Comet Wirtanen and begin to
    8.33
    3 votes
    50
    Gamma Arae

    Gamma Arae

    Gamma Arae (γ Ara, γ Arae) is a star in the southern constellation of Ara. With an apparent visual magnitude of 3.3, it is the fourth brightest star in the constellation and is readily visible to the naked eye. From parallax measurements made during the Hipparcos mission, the distance to this star can be estimated as 1,110 light-years (340 parsecs) from Earth. This is an enormous star with 23 times the radius of the Sun. It is radiating 120,000 as much energy as the Sun from its outer envelope at an effective temperature of 21,500 K. This heat gives the star the blue-white glow of a B-type star. The spectrum shows it to match a stellar classification of B1 Ib, with the luminosity class of 'Ib' indicating this is a lower luminosity supergiant star. It is a relatively young body, with an estimated age of around 15.7 million years. Gamma Arae is rotating rapidly with a projected rotational velocity of 269 km s, causing it to complete a full rotation about every 4.8 days. In the spectrum of this star, this high rate of spin is causing absorption lines to blend together because of the Doppler effect, making them more difficult to analyze. It is a periodically variable star that
    8.33
    3 votes
    51
    Iota Apodis

    Iota Apodis

    Iota Apodis (ι Aps, ι Apodis) is the Bayer designation for a binary star system in the southern circumpolar constellation of Apus. It is a faint target at an apparent visual magnitude of 5.41, but still visible to the naked eye from suitably dark skies. The distance to this star can be roughly gauged from parallax measurements, yielding an estimate of 1,300 light-years (400 parsecs) with a 20% margin of error. Both stars are B-type main sequence stars, which indicates they shine with a blue-white hue. The brighter component has a stellar classification of B9 V and an apparent magnitude 5.90, while the second member is a B9.5 V star with a magnitude of 6.46. The pair have an angular separation of 0.091 arcseconds with a preliminary estimated orbital period of 51.441 years. In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning Exotic Bird, refers to an asterism consisting of ι Apodis, ζ Apodis, β Apodis, γ Apodis, δ Octantis, δ Apodis, η Apodis, α Apodis and ε Apodis. Consequently, ι Apodis itself is known as 異雀二 (Yì Què èr, English: the Second Star of Exotic Bird.)
    8.33
    3 votes
    52
    Zeta Caeli

    Zeta Caeli

    Zeta Caeli (ζ Cae, ζ Caeli) is a star in the constellation Caelum. ζ Caeli is an orange K-type subgiant with an apparent magnitude of +6.35. It is approximately 514 light years from Earth.
    6.20
    5 votes
    53
    Theta1 C orionis

    Theta1 C orionis

    Theta Orionis C is a member of the Trapezium open cluster that lies within the Orion Nebula. The star C is the most massive of the four bright stars at the heart of the cluster. It is an O class blue main sequence star and has the highest surface temperature of any star visible to the naked eye; it is one of the most luminous stars known, with an estimated absolute magnitude in visible wavelengths of about −3.2. Its high luminosity and large distance (about 1,500 light years) give it an apparent visible magnitude of 5.1. This star is responsible for generating most of the ultraviolet light that is slowly ionizing (and perhaps photoevaporating) the Orion Nebula. This UV light is also the primary cause of the glow that illuminates the Orion Nebula. The star emits a powerful stellar wind that is a hundred thousand times stronger than the Sun's, and the outpouring gas moves at 1,000 km/s. Infrared observations of Theta Orionis C have shown that it is actually a close binary system. It also displays optical variability and is a variable X-ray source. It is expected that this star will expand into a red supergiant and end its life as a supernova within a few million years from now.
    9.50
    2 votes
    54
    Zeta Puppis

    Zeta Puppis

    Zeta Puppis (Zeta Pup, ζ Puppis, ζ Pup) is a star in the constellation of Puppis. It is also known by the traditional names Naos ( /ˈneɪ.ɒs/, from the Greek ναύς "ship") and Suhail Hadar (سهيل هدار, possibly "roaring bright one") in Arabic. Its spectral class is O4If, making it an exceptionally hot star, and it is one of the sky's few naked-eye class O-type stars. Its surface temperature is 42,400 K, or about seven times hotter than the surface of the Sun. Its mass is 40 solar masses. Unlike many other stars at such great distance, the precise parameters for Zeta Puppis including its velocity are known, and can extrapolate back to the region where it was formed, a molecular cloud in Vela. We can therefore derive a much more accurate distance than we can with, for example, Deneb. 2008 reductions of Hipparcos raw data give a distance of 335 parsecs (1,093 ly) ± 4%, and for Deneb, 475 pc ± 20%. Zeta Puppis is an extreme blue supergiant, one of the brightest stars in the Milky Way in terms of absolute magnitude. Visually, it is 21,000 times more powerful than the Sun, but being an extreme blue star most of its radiation is in the ultraviolet, and when this is considered it is
    9.50
    2 votes
    55
    Deimos

    Deimos

    • Orbits: Mars
    Deimos is a Mars moon with an average radius of 6.2 kilometres (3.9 mi), and an escape velocity of 5.6 m/s (20 km/h). It is the smaller and outer of Mars's two known moons, the other being Phobos. 23,460 km (14,580 mi) distant from Mars, Deimos takes 30.3 hours to orbit the planet at an orbital velocity of 1.35 km/s. Its systematic designation is Mars II. In English Deimos is pronounced  /ˈdaɪməs/ DY-məs; also /ˈdiːməs/ DEE-məs; Greek: Δείμος; also DAY-moce or DEE-moce. Deimos was discovered by Asaph Hall, Sr. at the United States Naval Observatory in Washington, D.C on August 12, 1877, at about 07:48 UTC (given in contemporary sources as "August 11 14:40" Washington mean time, using an astronomical convention of beginning a day at noon, so 12 hours must be added to get the actual local mean time). Hall also discovered Phobos on August 18, 1877, at about 09:14 GMT, after deliberately searching for Martian moons. It is named after Deimos, a figure representing dread in Greek Mythology. The names, at first spelled Phobus and Deimus, were suggested by Henry Madan (1838–1901), Science Master of Eton, from Book XV of the Iliad, where Ares (the Roman god Mars) summons Dread (Deimos) and
    7.00
    4 votes
    56
    SS 433

    SS 433

    SS 433 is one of the most exotic star systems observed. It is an eclipsing X-ray binary system, with the primary most likely a black hole, or possibly a neutron star. The spectrum of the secondary companion star suggests that it is a late A-type star. SS 433 is a microquasar, the first discovered. SS 433's designation comes from its catalogers, Case Western Reserve astronomers Nicholas Sanduleak and C. Bruce Stephenson. It was the 433rd entry in their 1977 catalog of stars with strong emission lines. The compact central object is consuming the companion star which rapidly loses mass into an accretion disc formed around the central object. The accretion disc is subject to extreme heating as it spirals into the primary and this heating causes the accretion disc to give off intense X-rays and opposing jets of hot hydrogen along the axis of rotation, above and below the plane of the accretion disc. The material in the jets travels at 26% of the speed of light. The companion star presumably had lower mass than the original primary object and was therefore longer lived. Estimates for its mass range from 3 to 30 solar masses. The primary and secondary orbit each other at a very close
    7.00
    4 votes
    57
    T Tauri

    T Tauri

    T Tauri is a variable star in the constellation Taurus, the prototype of the T Tauri stars. It was discovered in October 1852 by John Russell Hind. T Tauri appears from Earth amongst the Hyades cluster, not far from ε Tauri; but it is actually 420 light years behind it and was not formed with the rest of them. Like all T Tauri stars, it is very young, being only a million years old. Its distance from Earth is about 460 light years, and its apparent magnitude varies unpredictably from about 9.3 to 14. The T Tauri system consists of at least three stars, only one of which is visible at optical wavelengths; the other two shine in the infrared and one of them also emits radio waves. Through VLA radio observations, it was found that the young star (the "T Tauri star" itself) dramatically changed its orbit after a close encounter with one of its companions and may have been ejected from the system. Physically nearby is NGC 1555, a reflection nebula known as Hind's Nebula or Hind's Variable Nebula. It is illuminated by T Tauri, and thus also varies in brightness. The nebula NGC 1554 was likewise associated with T Tauri and was observed in 1868 by Otto Wilhelm von Struve, but soon
    7.00
    4 votes
    58
    73P/Schwassmann-Wachmann

    73P/Schwassmann-Wachmann

    73P/Schwassmann–Wachmann, also known as Schwassmann–Wachmann 3, is a periodic comet in the Solar System which is in the process of disintegrating. Starting the 2011 perihelion passage the primary component 73P-C was recovered on 28 November 2010 near apparent magnitude 21.3; it came to perihelion (closest approach to the Sun) on 16 October 2011. Comet Schwassmann–Wachmann 3, one of the comets discovered by astronomers by Arnold Schwassmann and Arno Arthur Wachmann, working at the Hamburg Observatory in Bergedorf, Germany, broke into fragments on its re-entry to the inner Solar System, May 1, 2006, in a reaction triggered by the Sun's heating the comet as it emerged from the frozen space of the outer Solar System. Comet 73P is a parent body of meteor shower Tau Herculids. The comet's initial discovery was serendipity: the astronomers were exposing photographic plates in search of minor planets, on photographs exposed for a minor planet survey, on May 2, 1930. The comet was lost after its 1930 apparition, but was observed several more times. 73P/Schwassmann–Wachmann has an orbital period of slightly less than 5 1/3 years so that it comes nearest to the Earth every 16 years. 73P was
    6.00
    5 votes
    59
    RR Lyrae

    RR Lyrae

    RR Lyrae is a variable star in the Lyra constellation, located near the border with the neighboring constellation of Cygnus. The variable nature of this star was discovered by the Scottish astronomer Williamina Fleming at Harvard Observatory in 1901. As the brightest star in its class, it became the eponym for the RR Lyrae variable class of stars and it has been extensively studied by astronomers. This type of low-mass star has consumed the hydrogen at its core, evolved away from the main sequence, and passed through the red giant stage. Energy is now being produced by the thermonuclear fusion of helium at its core, and the star has entered an evolutionary stage called the horizontal branch (HB). The effective temperature of an HB star's outer envelope will gradually increase over time. When its resulting stellar classification enters a range known as the instability strip—typically at stellar class A—the outer envelope can begin to pulsate. RR Lyrae shows just such a regular pattern of pulsation, which is causing its apparent magnitude to vary between 7.06–8.12 over a short cycle lasting 0.56686776 days (13 hours, 36 minutes). Each radial pulsation causes the radius of the star to
    6.00
    5 votes
    60
    Alpha Cephei

    Alpha Cephei

    Alpha Cephei (α Cep, α Cephei) is a second magnitude star in the constellation of Cepheus that is relatively close to Earth at only 49 light years. It has the traditional name Alderamin, an Arabic name meaning "the right arm". With a declination in excess of 62 degrees north, Alderamin is mostly visible to observers in the northern hemisphere, though the star is still visible as far south as ± 27° South latitude, albeit just above the horizon. The star is circumpolar throughout all of Europe, northern Asia, Canada and American cities as far south as San Diego on the west coast but not quite as far as Miami on the east coast. All other locations around the globe having a latitude greater than ± 27° North will notice that the star is always visible in the night sky. Since Alderamin has an apparent magnitude of about 2.5, the star is easily observable to the naked eye, even in light polluted cities. Alderamin is a white Class A star, evolving off of the main sequence into a subgiant, probably on its way to becoming a red giant as its hydrogen supply runs low. In 2007, the star's apparent magnitude was recalibrated at 2.5141 along with an updated parallax of 66.50 ± 0.11 mas yielding a
    8.00
    3 votes
    61
    Alpha Scuti

    Alpha Scuti

    Alpha Scuti (α Sct, α Scuti) is a fourth-magnitude star in the constellation Scutum. Alpha Scuti is an orange K-type giant with an apparent magnitude of +3.85. Alpha Scuti is a known variable star. It is approximately 174 light years from Earth. Alpha Scuti was a latter designation of 1 Aquilae.
    8.00
    3 votes
    62
    Gamma Camelopardalis

    Gamma Camelopardalis

    Gamma Camelopardalis (γ Cam / γ Camelopardalis) is a star in the constellation Camelopardalis. γ Camelopardalis is a white A-type subgiant with an apparent magnitude of +4.59. It is approximately 335 light years from Earth.
    8.00
    3 votes
    63
    Tau Canis Majoris

    Tau Canis Majoris

    Tau Canis Majoris (τ CMa, τ Canis Majoris) is an eclipsing spectroscopic binary in the constellation Canis Major and the brightest star of an open cluster designated NGC 2362. It is approximately 3200 light years from Earth. This star is sometimes known as the 'Mexican Jumping Star' by amateur astronomers, because it can appear to 'jump around' with respect to the other stars in the cluster because of its marked contrast in brightness. τ Canis Majoris is classified as an O-type blue supergiant with a mean apparent magnitude of +4.37. It is a Beta Lyrae type variable star with a period of 1.28 days, over which time its brightness varies from magnitude +4.32 to +4.37.
    8.00
    3 votes
    64
    Winnecke 4

    Winnecke 4

    Winnecke 4 (also known as Messier 40 or WNC 4) is a double star in the constellation Ursa Major. It was discovered by Charles Messier in 1764 while he was searching for a nebula that had been reported in the area by Johann Hevelius. Not seeing any nebulae, Messier catalogued this double star instead. It was subsequently rediscovered by Friedrich August Theodor Winnecke in 1863. Burnham calls M40 "one of the few real mistakes in the Messier catalog," faulting Messier for including it when all he saw was a double star, not a nebula of any sort. In 1991 the separation between the components was measured at 51".7, an increase since Messier's time. Data gathered by astronomers Brian Skiff (2001) and Richard L. Nugent (2002) strongly suggest that this is merely an optical double star rather than a physically connected system.
    8.00
    3 votes
    65
    Alpha Aquarii

    Alpha Aquarii

    Alpha Aquarii (Alpha Aqr, α Aquarii, α Aqr) is a single star in the Aquarius. It has the traditional name Sadalmelik, which is derived from Arabic for "Luck of the king". The apparent visual magnitude of 2.94 makes this the second-brightest star in Aquarius. Based upon parallax measurements made during the Hipparcos mission, this star is located at a distance of roughly 520 light-years (160 parsecs) from Earth. With an age of 53 million years, this star has evolved into a supergiant with a stellar classification of G2 Ib. It has 6.5 as much mass as the Sun and has expanded to around 77 times the Sun's radius. It is radiating 3,000 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 5,210 K. At this heat, the star glows with the yellow hue of a G-type star. Examination of this star with the Chandra X-ray Observatory shows it to be significantly X-ray deficient compared to G-type main sequence stars. This deficit is a common feature of early G-type giant stars. Sadalmelik has a visual companion, designated CCDM J22058-0019B, with an apparent visual magnitude of approximately 12.2. It is at an angular separation of 110.4 arcseconds from
    6.75
    4 votes
    66
    Beta Ursae Majoris

    Beta Ursae Majoris

    Beta Ursae Majoris (Beta UMa, β Ursae Majoris, β UMa) is a star in the northern circumpolar constellation of Ursa Major. It has the traditional name Merak. The apparent visual magnitude of this star is +2.37, which means it is readily visible to the naked eye. It is more familiar to northern hemisphere observers as one of the "pointer stars" in the Big Dipper, or "The Plough" in England, which is a prominent asterism of seven stars that forms part of the larger constellation. Extending an imaginary straight line from this star through the nearby Alpha Ursae Majoris (Dubhe) extends to Polaris, the north star. Based upon parallax measurements of this star, it is located at a distance of 79.7 light-years (24.4 parsecs) from the Earth. The spectrum shows this to have a stellar classification of A1 V, making it a fairly typical main sequence star that is generating energy through the thermonuclear fusion of hydrogen at its core. The effective temperature of the outer envelope is about 9,225 K, giving it a white-hued glow that is typical for A-type stars. It is larger than the Sun, with about 2.7 times the mass and 2.84 times the Solar radius. If they were viewed from the same distance,
    6.75
    4 votes
    67
    DQ Herculis

    DQ Herculis

    DQ Herculis (or Nova Herculis 1934) was a slow, bright nova occurring in Hercules in December 1934. It reached magnitude 1.5. DQ Herculis is the prototype for a category of cataclysmic variable stars called intermediate polars. The system shows orbital period variation, likely due to the presence of a third body. Dai & Qian (2009) invoke the presence of a third object to explain orbital period variations observed in the dwarf nova. If the third body is confirmed, it would likely turn out a brown dwarf companion.
    6.75
    4 votes
    68
    Epsilon Canis Minoris

    Epsilon Canis Minoris

    Epsilon Canis Minoris (ε CMi, ε Canis Minoris) is a star in the constellation Canis Minor. ε Canis Minoris is a yellow G-type bright giant with an apparent magnitude of +4.99. It is approximately 990 light years from Earth.
    6.75
    4 votes
    69
    Gamma Aquarii

    Gamma Aquarii

    Gamma Aquarii (γ Aqr, γ Aquarii) is the Bayer designation for a star in the constellation Aquarius. It has the traditional name Sadachbia, from an Arabic expression سعد الأخبية sa‘d al-’axbiyah "luck of the homes (tents)" in Hindu system it is also called Sadhabhisk in devnagari, sadhayam in tamil. This star has an apparent visual magnitude of 3.849, making it one of the brighter members of the constellation. Based upon parallax measurements, this star is located at a distance of roughly 164 light-years (50 parsecs) from the Sun, with an error margin of 5%. In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Aoul al Achbiya (أول ألأجبية - awwil al ahbiyah), which was translated into Latin as Prima Tabernaculorum, meaning the first of luck of the homes (tents). This star, along with π Aqr (Seat), ζ Aqr (Sadaltager / Achr al Achbiya) and η Aqr (Hydria), were al Aḣbiyah (الأخبية), the Tent. In Chinese, 墳墓 (Fén Mù), meaning Tomb, refers to an asterism consisting of γ Aquarii, ζ Aquarii, η Aquarii, π Aquarii. Consequently, γ Aquarii itself is known as 墳墓二 (Fén Mù èr, English: the Second Star of Tomb). Gamma Aquarii is an
    6.75
    4 votes
    70
    Teegarden's star

    Teegarden's star

    Teegarden's Star, also known as SO J025300.5+165258, is an M-type brown dwarf in the constellation Aries, located about 12 light years from the Solar System. Despite its proximity to Earth it is a dim magnitude 15 and can only be seen through large telescopes. This star was found to have a very large proper motion of about 5 arc seconds per year. Only seven stars with such large proper motions are currently known. Teegarden's Star was discovered in 2003 using asteroid tracking data that had been collected years earlier. This data set is a digital archive created from optical images taken over a 5-year period by the Near Earth Asteroid Tracking (NEAT) program using two 1-m telescopes located on Maui. The star is named after the discovery team leader, Bonnard Teegarden, an astrophysicist at NASA's Goddard Space Flight Center. Astronomers have long thought it was quite likely that many undiscovered dwarf stars exist within 20 light years of Earth, as stellar population surveys show the count of known nearby dwarf stars to be lower than otherwise expected and these stars are dim and easily overlooked. Teegarden's team thought that these dim stars might be found by data mining some of
    6.75
    4 votes
    71
    Comet Borrelly

    Comet Borrelly

    Comet Borrelly or Borrelly's Comet (official designation: 19P/Borrelly) is a periodic comet, which was visited by the spacecraft Deep Space 1 in 2001. The comet was discovered by Alphonse Borrelly during a routine search for comets at Marseilles, France on December 28, 1904. On September 21, 2001 the spacecraft Deep Space 1, which was launched to test new equipment in space, performed a flyby of Borrelly. It was steered toward the comet during the extended mission of the craft, and presented an unexpected bonus for the mission scientists. Despite the failure of a system that helped determine its orientation, Deep Space 1 managed to send back to Earth what were, at the time, the best images and other science data from a comet.
    9.00
    2 votes
    72
    Eta Leonis

    Eta Leonis

    Eta Leonis (η Leo, η Leonis) is a fourth-magnitude star in the constellation Leo. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Eta Leonis is a white supergiant with the stellar classification A0Ib. Though its apparent magnitude is 3.51, making it a relatively dim star to the naked eye, it is 5,600 times more luminous than the Sun, with an absolute magnitude of -5.60. The Hipparcos astrometric data has estimated the distance of Eta Leonis to be roughly 700 parsecs from Earth, or 2,000 light years away. There is evidence suggesting that Eta Leonis is part of a binary star system.
    9.00
    2 votes
    73
    Eta Ursae Majoris

    Eta Ursae Majoris

    Eta Ursae Majoris (Eta UMa, η Ursae Majoris, η UMa) is a star in the constellation Ursa Major. It has the traditional names Alkaid (or Elkeid) and Benetnash (Benetnasch). Alkaid is the most eastern (leftmost) star in the Big Dipper (Plough) asterism. However, unlike most stars of the Big Dipper, it is not a member of the Ursa Major moving group. With an apparent visual magnitude of +1.84, it is the third brightest star in the constellation and one of the brightest stars in the night sky. This is a 10 million year old B-type main sequence star with a stellar classification of B3 V. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It has six times the mass of the Sun and 3.4 times the Sun's radius. Eta Ursae Majoris is radiating around 1,350 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of about 16,823 K, giving it the blue-white hue of a B-type star. This star is an X-ray emitter with a luminosity of 9.3 × 10 erg s.
    9.00
    2 votes
    74
    Galactic Center

    Galactic Center

    • Orbited by: Sun
    The Galactic Center is the rotational center of the Milky Way galaxy. It is located at a distance of 8.33±0.35 kpc (~27,000±1,000 ly) from the Earth in the direction of the constellations Sagittarius, Ophiuchus, and Scorpius where the Milky Way appears brightest. There is strong evidence that supports the existence of a supermassive black hole at the Galactic Center of the Milky Way. Because of interstellar dust along the line of sight, the Galactic Center cannot be studied at visible, ultraviolet or soft X-ray wavelengths. The available information about the Galactic Center comes from observations at gamma ray, hard X-ray, infrared, sub-millimetre and radio wavelengths. Coordinates of the Galactic Center were first found by Harlow Shapley in his 1918 study of the distribution of the globular clusters. In the Equatorial coordinate system they are: RA 17h45m40.04s, Dec -29° 00' 28.1" (J2000 epoch). The exact distance from the Sun to the Galactic Center is notoriously uncertain. The latest estimates from geometric-based methods and standard candles yield distances to the Galactic Center between 7.6–8.7 kpc (25,000–28,000 light years). An accurate determination of the distance to the
    9.00
    2 votes
    75
    Theta Eridani

    Theta Eridani

    Theta Eridani (θ Eri, θ Eridani) is a star in the constellation Eridanus. It has the traditional name Acamar from the Arabic آخِر النَّهْر  Ākhir an-nahr which means "the end of the river". Historically, Acamar represented the end of the constellation Eridanus. Now that distinction is held by the star Achernar, a star which shares the same Arabic etymology. Achernar is not visible from the Greek isles (latitudes > 33° North), hence the choice of Acamar as the river's end during the time of Hipparchus and later Ptolemy. The term Ākhir an-nahr or Achr al Nahr was appeared in the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, which was translated into Latin as Postrema Fluminis. In Chinese, 天園 (Tiān Yuán), meaning Celestial Orchard, refers to an asterism consisting of θ Eridani, χ Eridani, φ Eridani, κ Eridani, HD 16754, HD 23319, HD 24072, HD 24160, υ Eridani, 43 Eridani, υ Eridani and υ Eridani. Consequently, θ Eridani itself is known as 天園六 (Tiān Yuán liù, English: the Sixth Star of Celestial Orchard.) Acamar is a double star with some evidence suggesting it is part of a multiple star system. The main star, θ Eri, is of the spectral class A4 and has a +3.2
    9.00
    2 votes
    76
    VZ Camelopardalis

    VZ Camelopardalis

    VZ Camelopardalis (VZ Cam) is a Semiregular variable star in the constellation Camelopardalis. VZ Camelopardalis is a M-type red giant with a mean apparent magnitude of +4.92. It is approximately 473 light years from Earth. It is classified as a semiregular variable star and its brightness varies from magnitude +4.80 to +4.96 with a period of 23.7 days.
    9.00
    2 votes
    77
    Zeta Leonis

    Zeta Leonis

    Zeta Leonis (ζ Leo, ζ Leonis) is a third-magnitude star in the constellation Leo, the lion. It has the traditional name Adhafera (Aldhafera, Adhafara), from the Arabic الضفيرة al-ðafīrah "the braid/curl", a reference to its position in the lion's mane. It forms the second star (after Gamma Leonis) in the blade of "The Sickle", which is an asterism formed from the head of Leo. Adhafera is a giant star with a stellar classification of F0 III. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Its apparent magnitude is +3.44, making it relatively faint for a star that is visible to the naked eye. Nevertheless, it shines with 85 times the luminosity of the Sun. Adhafera has about three times the Sun's mass and six times the radius of the Sun. Parallax measurements from the Hipparcos satellite yield an estimated distance to Adhafera of 274 light-years (84 parsecs) from Earth. Adhafera forms a double star with an optical companion that has an apparent magnitude of 5.90. Known as 35 Leo, this star is separated from Adhafera by 325.9 arcseconds along a position angle of 340°. The two stars do not form a binary star
    9.00
    2 votes
    78
    4183 Cuno

    4183 Cuno

    • Orbits: Sun
    4183 Cuno is an Apollo, Mars- and Venus-crosser asteroid. It was discovered in 1959 by Cuno Hoffmeister, from whom the asteroid takes its name. Cuno is about 4–9 km in diameter and is an S-type asteroid, meaning that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates. In December 2000, Cuno was analysed by radar to determine its shape. The resultant images are lacking in detail, but indicate a rough sphere with some kind of concave depression 1–2 km in diameter. 4183 Cuno approaches the Earth to within 40 Gm six times in the 21st century. On 2012-May-20 Cuno made its closest Earth approach at a distance of 0.12182 AU (18,224,000 km; 11,324,000 mi). It will not make a closer approach until 2093.
    7.67
    3 votes
    79
    Eta Aquilae

    Eta Aquilae

    Eta Aquilae (η Aql, η Aquilae) is the Bayer designation for a star in the equatorial constellation of Aquila, the eagle. It was once part of the former constellation Antinous. On average, this star has an apparent visual magnitude of 3.87, making it one of the brighter members of Aquila. Based upon parallax measurements made during the Hipparcos mission, this star is located at a distance of roughly 1,382 light-years (424 parsecs), although the parallax estimate has a 44% margin of error. This is a Cepheid variable star, with an apparent magnitude that ranges from 3.5 to 4.4 over a period of 7.176641 days. Along with Delta Cephei, Zeta Geminorum and Beta Doradus, it is one of the most prominent naked eye Cepheids; that is, both the star itself and the variation in its brightness can be distinguished with the naked eye. Some other Cepheids such as Polaris are bright but have only a very small variation in brightness. At the relatively young age of 26 million years, this massive star has burned through the hydrogen fuel at its core and evolved into a supergiant, giving it a baseline stellar classification of F6 Ibv. The Ib luminosity class indicates this is a less luminous type of
    7.67
    3 votes
    80
    Eta Canis Minoris

    Eta Canis Minoris

    Eta Canis Minoris (η CMi, η Canis Minoris) is a binary star in the constellation Canis Minor. It is approximately 351 light years from Earth. The primary component, η Canis Minoris A, is a yellow-white F-type giant with an apparent magnitude of +5.24., It's companion, η Canis Minoris B, is an eleventh magnitude star located 4 arcseconds from the primary.
    7.67
    3 votes
    81
    Gamma Canis Minoris

    Gamma Canis Minoris

    Gamma Canis Minoris (γ CMi, γ Canis Minoris) is a binary star in the constellation Canis Minor. It is approximately 398 light years from Earth. γ Canis Minoris is an orange K-type giant with an apparent magnitude of +4.34. It is a spectroscopic binary, and it has an unresolved companion which has an orbital period of 389 days. Its orange colour is obvious when seen through binoculars.
    7.67
    3 votes
    82
    Gamma Orionis

    Gamma Orionis

    Bellatrix, also known by its Bayer designation Gamma Orionis (γ Ori, γ Orionis), is the third brightest star in the constellation Orion. A second-magnitude star, it is the twenty-seventh brightest star in the night sky. The name Bellatrix is Latin for female warrior. In the Alfonsine tables, it was also called the Amazon Star, a loose translation of the Arabic name Al Najīd, the Conqueror. It forms the left shoulder of Orion the Hunter. Bellatrix is one of the four navigational stars in Orion that are used for celestial navigation. The Chinese name for the star is 参宿五 ("The Fifth of the Three Stars"). This is a massive star with about 8.4 times the Sun's mass. It has an estimated age of approximately 20 million years; long enough for a star of this mass to consume the hydrogen at its core and begin to evolve away from the main sequence into a giant star. The effective temperature of the outer envelope of this star is 22,000 K, which is considerably hotter than the 5,778 K on the Sun. This high temperature gives this star the blue-white hue that occurs with B-type stars. The measured angular diameter of this star, after correction for limb darkening, is 0.72 ± 0.04 mas. At an
    7.67
    3 votes
    83
    118P/Shoemaker-Levy

    118P/Shoemaker-Levy

    118P/Shoemaker–Levy (also known as periodic comet Shoemaker-Levy 4) is a comet discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. During the 2010 apparition the comet became as bright as apparent magnitude 11.5. The comet nucleus is estimated to be 4.8 kilometers in diameter. On December 3, 2015, comet Shoemaker-Levy 4 will pass 0.0442 AU (6,610,000 km; 4,110,000 mi) from asteroid 4 Vesta. This comet should not be confused with Comet Shoemaker-Levy 9 (D/1993 F2) which spectacularly crashed into Jupiter in 1994.
    10.00
    1 votes
    84
    21P/Giacobini-Zinner

    21P/Giacobini-Zinner

    Comet Giacobini–Zinner (official designation: 21P/Giacobini–Zinner) is a periodic comet in the Solar System. It was discovered by Michel Giacobini from (Nice, France), who observed the comet in the constellation of Aquarius on December 20, 1900. It was recovered two passages later by Ernst Zinner (from Bamberg, Germany) while observing variable stars near Beta Scuti on October 23, 1913. During its apparitions, Giacobini–Zinner can reach about the 8th magnitude, but in 1946 it underwent a series of outbursts that made it as bright as 5th magnitude. It is the parent body of the Giacobinids meteor shower (also known as the Draconids). Giacobini–Zinner was the target of the International Cometary Explorer spacecraft, which passed through its plasma tail on September 11, 1985. In addition, Japanese space officials considered redirecting the Sakigake interplanetary probe toward a 1998 encounter with Giacobini–Zinner, but that probe lacked the propellant for the necessary maneuvers and the project was abandoned. The comet nucleus is estimated to be 2.0 kilometers in diameter.
    10.00
    1 votes
    85
    79 Ceti

    79 Ceti

    79 Ceti (also known as HD 16141) is a yellow subgiant star approximately 127 light-years away in the constellation Cetus. It has stopped hydrogen fusion in its core, this implies an age much higher than our Sun's 4.5 billion years. Eventually the outer layers of the star will expand and cool and the star will become a red giant. Currently 79 Ceti has a luminosity twice that of the Sun. As of 2000, an extrasolar planet, designated 79 Ceti b, is known to orbit 79 Ceti.
    10.00
    1 votes
    86
    Gamma Boötis

    Gamma Boötis

    Gamma Boötis (γ Boo, γ Boötis) is a star in the constellation Boötes. It has the traditional name Seginus (also Segin, Ceginus) of uncertain origin. It was listed as Haris in Bečvář. Gamma Boötis is approximately 85 light years away from Earth. It belongs to the spectral class A7III. It is a Delta Scuti type variable star with a period of 1.13 hours. Its brightness varies from magnitude +3.02 to +3.07. In Chinese astronomy, Seginus is called 招搖, Pinyin: Zhāoyáo, meaning Twinkling Indicator, because this star is marking itself and stand alone in Twinkling Indicator asterism, Root mansion (see : Chinese constellation). 招搖 (Zhāoyáo), westernized into Chaou Yaou, but the name Chaou Yaou was designated for β Boötis (Nekkar) by R.H. Allen and the meaning is "to beckon, excite, or move." In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Menkib al Aoua al Aisr (منكب العواء الأيسر - mankibu lʿawwaaʾi lʾaysar), which was translated into Latin as Humerus Sinister Latratoris, meaning the left shoulder of barker. The name Seginus resulted from Latinization of an Arabic form of the Greek name of the constellation of Boötes (Theguius). The name
    10.00
    1 votes
    87
    2004 FH

    2004 FH

    2004 FH is a near-Earth asteroid that was discovered on March 15, 2004, by the NASA-funded LINEAR asteroid survey. The object is roughly 30 metres in diameter and passed just 43,000 km (27,000 mi) above the Earth's surface on March 18, 2004, at 22:08 UTC; making it the 11th closest approach to Earth recorded as of 21 November 2008 (2008 -11-21) (see the diagram below). For comparison, geostationary satellites orbit Earth at 35,790 km. 2004 FH is an Aten family asteroid, although by some definitions it should be called a meteoroid, since it is smaller than 50 metres in diameter. Despite its relatively small size (about 30 metres), it is still the fourth largest asteroid detected coming closer to the Earth than the Moon. Had this object hit Earth, it would probably have detonated high in the atmosphere. It might have produced a blast measured in hundreds of kilotons of TNT, but may not have produced any effect on the ground. It could also have been an Earth-grazing fireball if it had been much closer but not close enough to impact. On 2044-Mar-17 the asteroid will pass no closer than 0.0116 AU (1,740,000 km; 1,080,000 mi) from the Earth. 2004 FH also has the distinction of having the
    6.50
    4 votes
    88
    Nu Andromedae

    Nu Andromedae

    Nu Andromedae (Nu And, ν Andromedae, ν And) is a binary star in the constellation Andromeda. The system has an apparent visual magnitude of 4.5, which is bright enough to be seen with the naked eye. It is approximately 620 light-years (190 parsecs) from Earth. Situated just over a degree to the west of this star is the Andromeda Galaxy. Nu Andromedae is spectroscopic binary system with a nearly circular orbit that has a period of 4.2828 days. The primary component is a B-type main sequence star with a stellar classification of B5 V. The fainter secondary has a classification of F8 V, which makes it an F-type main sequence star. The pair are about 63 million years old. In Chinese, 奎宿 (Kuí Sù), meaning Legs (asterism), refers to an asterism consisting of ν Andromedae, η Andromedae, 65 Piscium, ζ Andromedae, ε Andromedae, δ Andromedae, π Andromedae, μ Andromedae, β Andromedae, σ Piscium, τ Piscium, 91 Piscium, υ Piscium, φ Piscium, χ Piscium and ψ¹ Piscium. Consequently, ν Andromedae itself is known as 奎宿七 (Kuí Sù qī, English: the Seventh Star of Legs.)
    6.50
    4 votes
    89
    4486 Mithra

    4486 Mithra

    • Orbits: Sun
    4486 Mithra is an Apollo and Mars-crosser asteroid. It was discovered by Eric Elst and Vladimir Shkodrov on September 22, 1987. It is named after Mithra, Indo-Iranian god of light. In Asia Minor around 330 B.C. the god Mithra was identified with the Greek god Apollo, hence the name. In 2000 it made a very close approach to Earth, passing 6.96 million km, or 0.047 au from it. The asteroid measures 2–5 km in diameter. Its shape has been analyzed by radar, and has been revealed as bizarre: it is the most highly bifurcated object in the solar system, with two distinct lobes.
    8.50
    2 votes
    90
    Gamma Aquilae

    Gamma Aquilae

    Gamma Aquilae (γ Aql, γ Aquilae) is a star in the constellation Aquila. It has the traditional name Tarazed. This star has an apparent visual magnitude of 2.712, so it is readily visible to the naked eye at night. Parallax measurements place it at a distance of 395 light-years (121 parsecs) from Earth. Gamma Aquilae is a relatively young star with an age of about 100 million years. Nevertheless, it has reached a stage of its evolution where it has consumed the hydrogen at its core and expanded into what is termed a bright giant star, with a stellar classification of K3 II. The star is now burning helium into carbon in its core. After it has finished generating energy through nuclear fusion, Gamma Aquilae will become a white dwarf. The interferometry-measured angular diameter of Gamma Aquilae is 7.271 ± 0.073 mas, which, at its estimated distance, equates to a physical radius of about 95 times the radius of the Sun. With almost six times the Sun's mass, this is an enormous star that is radiating over 2,500 times the luminosity of the Sun. An effective temperature of 4,210 K in its outer envelope gives it the orange hue typical of K-type stars. The traditional name Tarazed may derive
    8.50
    2 votes
    91
    Gamma Geminorum

    Gamma Geminorum

    Gamma Geminorum (γ Gem, γ Geminorum) is the second brightest star in the constellation Gemini. It has the traditional names Alhena and Almeisan. This star has an apparent visual magnitude of 1.9, making it easily visible to the naked eye even in urban regions. Based upon parallax measurements with the Hipparcos satellite, it is located at a distance of roughly 109 light-years (33 parsecs) from Earth. Alhena is an evolving star that is exhausting the supply of hydrogen at its core and has entered the subgiant stage. The spectrum matches a stellar classification of A1 IV. Compared to the Sun it has 2.8 times the mass and 3.3 times the radius. It is radiating around 123 times the luminosity of the Sun from its outer envelope at an effective temperature of 9,260 K. This gives it a white hue typical of an A-class star. This is a spectroscopic binary system with a period of 12.6 years (4,614.51 days) in a highly eccentric Keplerian orbit. The term Alhena is derived from the Arabic الهنعه Al Han'ah, "the brand" (on the neck of the camel), whilst the alternate name Almeisan is from the Arabic المیسان Al Maisan, "the shining one." Al Hanʽah was the name of star association consisting this
    8.50
    2 votes
    92
    Theta Arae

    Theta Arae

    Theta Arae (θ Ara, θ Arae) is the Bayer designation for a star in the constellation Ara. It has an apparent visual magnitude of +3.67, which is bright enough to be seen with the naked eye. Based upon an annual parallax shift of 4.01 mas, Theta Arae is 810 light-years (250 parsecs) distant from the Earth. This is a supergiant star with a stellar classification of B2 Ib. It has nearly nine times the mass of the Sun and is over 20 times the Sun's radius. The outer atmosphere of this star has an effective temperature of 17,231 K; much hotter than the surface of the Sun. At this heat, the star shines with the characteristic blue-white hue of a B-type star.
    8.50
    2 votes
    93
    Zeta Boötis

    Zeta Boötis

    Zeta Boötis (ζ Boo, ζ Boötis) is a binary star system in the constellation of Boötes that consists of two giant stars with matching stellar classifications of A2III. They have the Flamsteed designation 30 Boötis. This system is approximately 180 light years from Earth and has a combined apparent magnitude of +3.78. The individual magnitudes differ slightly, with component A having a magnitude of 4.43 and component B at the slightly dimmer magnitude 4.83. The binary nature of this system has been tracked since 1796. They complete an orbit roughly every 45,460 days, or 124.46 years. The next close approach will occur during August 2023. The orbit of this pair has a very high eccentricity of 0.9977, bringing the stars within 0.3 AU at their closest approach.
    8.50
    2 votes
    94
    Zeta Ophiuchi

    Zeta Ophiuchi

    Zeta Ophiuchi (ζ Oph, ζ Ophiuchi) is a star located in the constellation of Ophiuchus. It has an apparent visual magnitude of 2.57, making it the third brightest star in the constellation. Parallax measurements give an estimated distance of roughly 366 light-years (112 parsecs) from the Earth. ζ Ophiuchi is an enormous star with more than 19 times the Sun's mass and eight times its radius. The stellar classification of this star is O9.5 V, with the luminosity class of V indicating that it is generating energy in its core by the nuclear fusion of hydrogen. This energy is being emitted from the outer envelope at an effective temperature of 34,000, giving the star the blue hue of an O-type star. It is rotating rapidly and may be close to the velocity at which it would begin to break up. The projected rotational velocity may be as high as 400 km s and it may be rotating at a rate of once per day. This is a young star with an age of only three million years. Its luminosity of the star is varying in a periodic manner similar to a Beta Cephei variable. This periodicity has a dozen or more frequencies ranging between 1–10 cycles per day. In 1979, examination of the spectrum of this star
    8.50
    2 votes
    95
    3C58

    3C58

    3C58 or 3C 58 is a pulsar and supernova remnant within the Milky Way that is possibly associated with the supernova SN 1181. There are, however, signs that indicate that it could be several thousand years old, and thus not associated with that supernova. 3C58 is notable for its very high rate of cooling which is unexplained by standard theories of neutron star formation. It is hypothesized that extreme conditions in the star's interior cause a high neutrino flux, which carries away the energy and the star cools. It is located in the direction of Cassiopeia and is estimated to be 10,000 light-years away. 3C58 has been proposed as a possible quark star. Media related to 3C 58 at Wikimedia Commons
    7.33
    3 votes
    96
    Alpha Arae

    Alpha Arae

    Alpha Arae (α Arae, α Ara) is the second brightest star in the southern constellation of Ara. With an average apparent visual magnitude 2.93, it is readily visible to the naked eye from the southern hemisphere. This star is close enough to the Earth that its distance can be estimated using parallax data collected during the Hipparcos mission. It is around 270 light-years (83 parsecs) away, with a 7% margin of error. The visual magnitude of the star is diminished by 0.10 magnitudes as a result of extinction from intervening gas and dust. Alpha Arae has a stellar classification of B2 Vne, indicating that it is a massive B-type main sequence star. The 'n' notation in the suffix indicates that the absorption lines in the star's spectrum appear spread out and nebulous because of the Doppler effect from rapid rotation. The measured projected rotational velocity has been measured as high as 375 km s. Meilland et al. (2007) estimate the pole of the star is inclined by 55° to the line of sight, yielding an equatorial azimuthal velocity of 470 km s. This is close to the critical velocity where the star would start to breakup. The rapid rotation is causing a pronounced equatorial bulge of
    7.33
    3 votes
    97
    Theta Antliae

    Theta Antliae

    Theta Antliae (θ Ant, θ Antliae) is the Bayer designation for a binary star in the southern constellation of Antlia. The pair have a combined apparent visual magnitude of +4.78; the brighter component is magnitude +5.30 while the secondary is +6.18. Based upon parallax measurements, it is located at a distance of around 340 light-years (100 parsecs) from Earth. The primary component of this system, θ Ant A, has a stellar classification of A8 Vm, indicating that it is an A-type main sequence star with enhanced metallic lines in its spectrum. The companion, θ Ant B, is a giant star with a classification of G7 III. The pair have an orbital period of 18.3 years, a significant eccentricity of 0.445, and they have an angular separation of 0.1 arcseconds.
    7.33
    3 votes
    98
    5D/Brorsen

    5D/Brorsen

    5D/Brorsen (also known as Brorsen's Comet or Comet Brorsen) was a periodic Jupiter-family comet discovered February 26, 1846, by the Danish astronomer Theodor Brorsen. The perihelion of 5D/Brorsen was February 25, just a day before its discovery, and maintained the approach to Earth after that, passing closest to Earth on March 27 (at a distance of 0.52 AU). As a result of this close encounter to Earth the comet's coma diameter increased. Johann Friedrich Julius Schmidt estimating it as 3 to 4 arcmin across on March 9, and 8 to 10 arcmin across on the 22nd of that same month. Last seen on April 22, it was stationed about 20 degrees from the north celestial pole. By the end of this first apparition the orbital period was identified as 5.5 years. It was discovered that a close approach to Jupiter in 1842 put in its discovery orbit. The comet's 5.5 year period would mean that apparitions would alternate between good and poor. As expected, the comet was missed in its 1851 apparition, when the comet only came as close as 1.5 AU to earth. The comet's orbit was still relatively uncertain, made worse by the fact it had approached Jupiter in 1854. In 1857, Karl Christian Bruhns found a
    6.25
    4 votes
    99
    Alpha Coronae Borealis

    Alpha Coronae Borealis

    Alpha Coronae Borealis (α CrB, α Coronae Borealis) is a binary star in the constellation Corona Borealis. It is located about 75 light years from the Solar System. The primary component is a white main sequence star that has a stellar classification of A0V and 2.6 times the mass of the Sun. Estimates of the star's radius range from 2.89 to 3.04 times the radius of the Sun. An excess of infrared radiation at 24 μm and 70 μm has been detected about the primary star by the IRAS. This suggests the presence of a large disc of dust and material around Alphecca, prompting speculation of a planetary or proto-planetary system similar to that currently assumed around Vega. The secondary component is a yellow main sequence star with an estimated stellar class of G5, 0.92 times the Sun's mass and 0.90 times the Sun's radius. The X-ray luminosity of this star is 6 × 10 erg s, which is 30 times greater than the peak activity level of the Sun. This higher activity level is expected for a young star of this class. The corona has a temperature of about 5 MK, which is much hotter than the Sun's corona. The upper limit of 14 km/s for the equatorial rotation velocity is equivalent to a rotation period
    6.25
    4 votes
    100
    4U 0142+61

    4U 0142+61

    4U 0142+61 is a magnetar at an approximate distance of 13,000 light-years from Earth, located in the constellation Cassiopeia. In an article published in Nature on April 6, 2006, Deepto Chakrabarty et al. of MIT revealed that a circumstellar disk was discovered around the pulsar. This may prove that pulsar planets are common around neutron stars. The debris disk is likely to be composed of mainly heavier metals. The star had undergone a supernova event approximately 100,000 years ago. The disk orbits about 1.6 million kilometers away from the pulsar and probably contains about 10 Earth-masses of material.
    7.00
    3 votes
    101
    Alpha Apodis

    Alpha Apodis

    Alpha Apodis (Alpha Aps, α Apodis, α Aps) is the brightest star in the southern circumpolar constellation of Apus, with an apparent magnitude of approximately 3.825. It had the Greek alpha designation at part of the constellation Johann Bode called Apis Indica in his 1603 Uranometria star atlas. With a declination of –79°, this is a circumpolar star for much of the southern hemisphere. It can be identified on the night sky by drawing an imaginary line through Alpha Centauri and Alpha Circini then extending it toward the south celestial pole. This is a giant star with a stellar classification of K2.5III, indicating that this star has consumed the hydrogen at its core and has evolved away from the main sequence. It has expanded to an estimated radius of about 48 times the radius of the Sun and is emitting 980 times the Sun's luminosity. The photosphere has an effective temperature of 4,256 K, giving the star the characteristic orange hue of a K-type star. Based upon parallax measurements, this star is roughly 447 light-years from the Earth. It is not known to have a companion. In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system,
    7.00
    3 votes
    102
    Comet Biela

    Comet Biela

    Biela's Comet or Comet Biela (official designation: 3D/Biela) was a periodic Jupiter-family comet first recorded in 1772 by Montaigne and Messier and finally identified as periodic in 1826 by Wilhelm von Biela. It was subsequently observed to split in two and has not been seen since 1852. As a result it is currently considered to have been destroyed, although remnants appeared to have survived for some time as a meteor shower. The comet was first recorded on 8 March 1772 by Jacques Leibax Montaigne; during the same apparition it was independently discovered by Charles Messier. It was also recorded in 1805 by Jean-Louis Pons, but was not recognized as the same object. After the 1772 and 1805 apparitions a number of attempts were made by Lalande (1774), Gauss (1806) and Bessel (1806) to calculate a definitive orbit, Gauss and Olbers both noting a similarity between the 1805 and 1772 comets, but it was not possible to prove a link. It was Wilhelm von Biela, an army officer serving at the fortress town of Josefstadt, who observed the comet during its 1826 perihelion approach (on February 27) and calculated its orbit, discovering it to be periodic with a period of 6.6 years. At the time
    7.00
    3 votes
    103
    Delta Arae

    Delta Arae

    Delta Arae (δ Arae, δ Ara) is the Bayer designation for a double star in the southern constellation Ara. It has an apparent visual magnitude of 3.62 and is visible to the naked eye. Based upon an annual parallax of 16.48 mas, it is about 198 light-years (61 parsecs) distant from the Earth. Delta Arae is massive B-type main sequence star with a stellar classification of B8 Vn. The 'n' suffix indicates the absorption lines are spread out broadly because the star is spinning rapidly. It has a projected rotational velocity of 255 km/s, resulting in an equatorial bulge with a radius 13% larger than the polar radius. It has a magnitude 9.5 companion G-type main sequence star that may form a binary star system with Delta Arae. There is a 12th magnitude optical companion located 47.4 arcseconds away along a position angle of 313°. Delta Arae was known as 龜三 (meaning: "the 3rd (star) of Guī") in traditional Chinese astronomy. Allen erroneously called it with ζ Arae as Tseen Yin (天陰). He probably confused constellation "Ara" with "Ari". Tseen Yin was lain in Aries.
    7.00
    3 votes
    104
    Great Comet of 1843

    Great Comet of 1843

    The Great Comet of 1843 formally designated C/1843 D1 and 1843 I, was a long-period comet which became very bright in March 1843 (it is also known as the Great March Comet). It was discovered on February 5, 1843 and rapidly brightened to become a great comet. It was a member of the Kreutz Sungrazers, a family of comets resulting from the breakup of a parent comet (X/1106 C1) into multiple fragments in about 1106. These comets pass extremely close to the surface of the Sun—within a few solar radii—and often become very bright as a result. First observed in early February, 1843, it raced toward an incredibly close perihelion of less than 830,000 km on February 27, 1843; at this time it was observed in broad daylight roughly a degree away from the Sun. It passed closest to Earth on March 6, 1843, and was at its greatest brilliance the following day; unfortunately for observers north of the equator, at its peak it was best visible from the Southern Hemisphere. It was last observed on April 19, 1843. At that time this comet had passed closer to the sun than any other known object. The Great Comet of 1843 developed an extremely long tail during and after its perihelion passage. At over 2
    7.00
    3 votes
    105
    R Horologii

    R Horologii

    R Horologii (also known as HD 18242) is a red giant star approximately 100 light-years away in the constellation Horologium. It is also a Mira variable with a period of 407.6 days, and has one of the largest magnitude ranges known (from 4.7 to 14.3).
    6.00
    4 votes
    106
    V849 Ophiuchi

    V849 Ophiuchi

    V849 Ophiuchi or Nova Ophiuchi 1919 was a nova that lit up in 1919 in the constellation Ophiuchus and reached a brightness of 7.4 mag.
    6.00
    4 votes
    107
    Delta Caeli

    Delta Caeli

    Delta Caeli (δ Cae, δ Caeli) is a star in the constellation Caelum. It is a blue-white B-type subgiant with an apparent magnitude of +5.07. It is approximately 711 light years from Earth.
    8.00
    2 votes
    108
    Delta Cassiopeiae

    Delta Cassiopeiae

    Delta Cassiopeiae (δ Cas, δ Cassiopeiae) is a star in the northern circumpolar constellation of Cassiopeia. It has the traditional names Ksora and Ruchbah, derived from the Arabic word ركبة rukbah meaning "knee". It is not to be confused with Alpha Sagittarii, which also is called Ruchbah or Rukbat. In Chinese, 閣道 (Gé Dào), meaning Flying Corridor, refers to an asterism consisting of δ Cassiopeiae, ι Cassiopeiae, ε Cassiopeiae, θ Cassiopeiae, ν Cassiopeiae and ο Cassiopeiae. Consequently, δ Cassiopeiae itself is known as 閣道三 (Gé Dào sān, English: the Third Star of Flying Corridor.) Delta Cassiopeiae is an eclipsing binary star system consisting of a pair of stars that orbit about each other over a period of 759 days. The combined apparent visual magnitude of the two stars is 2.68, making it readily observable with the naked eye. However, this magnitude varies between +2.68 mag and +2.74 as the stars pass in front of each other. Based on parallax measurements, this system is about 99.4 light-years (30.5 parsecs) from the Earth. The primary member of the system has a stellar classification of A5III-IVv, with the luminosity class of IV indicating that it has exhausted the hydrogen at
    8.00
    2 votes
    109
    Jupiter

    Jupiter

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Io
    Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets. The planet was known by astronomers of ancient times, and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly match Jupiter's brightness at certain points in its orbit.) Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, although helium only comprises about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other gas giants, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it
    8.00
    2 votes
    110
    R Coronae Borealis

    R Coronae Borealis

    R Coronae Borealis is a yellow supergiant star, and is the prototype of the RCB class of variable stars, which fade by several magnitudes at irregular intervals. R Coronae Borealis itself normally shines at approximately magnitude 6, just about visible to the naked eye, in the constellation of Corona Borealis, but at intervals of several months to many years fades to as faint as magnitude 14. Over successive months it gradually returns to its normal brightness, giving it the nickname "Fade-Out star," or "Reverse Nova". The cause of this behaviour is believed to be a regular build-up of carbon dust in the star's atmosphere. The sudden drop in brightness may be caused by a rapid condensation of dust, resulting in much of the star's light being blocked. The gradual restoration to normal brightness results from the dust being dispersed by radiation pressure. Variability of R CrB has been discovered by the English astronomer, Edward Pigott in 1795. It was known as Variabilis Coronae, "Variable of Corona". In 1935 it was the first star shown to have a different chemical composition than the sun via spectral analysis.
    8.00
    2 votes
    111
    Upsilon Boötis

    Upsilon Boötis

    Upsilon Boötis (υ Boo, υ Boötis) is a star in the constellation Boötes. Upsilon Boötis is an orange K-type giant with an apparent magnitude of +4.05. It is approximately 263 light years from Earth.
    8.00
    2 votes
    112
    Alpha Ophiuchi

    Alpha Ophiuchi

    Alpha Ophiuchi (α Oph, α Ophiuchi) is the brightest star in the constellation Ophiuchus. It has the traditional name Ras Alhague, often condensed to Rasalhague. Alpha Ophiuchi is a binary star system with an orbital period of about 8.62 years. The orbital parameters were only poorly known until 2011 when observations using adaptive optics produced a better orbital fit, allowing the individual masses of the two components to be determined. The primary component, Alpha Ophiuchi A, has a mass of about 2.4 times the mass of the Sun, while the secondary, Alpha Ophiuchi B, has 0.85 solar masses. Estimates of the mass of the primary by other means range from a low of 1.92 to 2.10 solar masses, up to 2.84 or even 4.8 solar masses. The mass of the secondary suggests that it has a stellar classification in the range K5V to K7V, which indicates it is a main sequence star that is still generating energy by the thermonuclear fusion of hydrogen at its core. The pair reached periastron passage, or closest approach, around April 19, 2012, when they had an angular separation of 50 milliarcseconds. This star system has a combined apparent magnitude of +2.08 and is located at a distance of about 48.6
    9.00
    1 votes
    113
    Beta Ophiuchi

    Beta Ophiuchi

    Beta Ophiuchi (β Oph, β Ophiuchi) is a star in the equatorial constellation of Ophiuchus. It has the traditional names Celbalrai, which comes from the Arabic كلب الراعي kalb al-rā‘ī meaning "shepherd dog". It is also called Cheleb, Kelb Alrai, or sometimes just Alrai. the apparent visual magnitude of this star is 2.7, which is readily visible to the naked eye even from urban skies. The distance to this star can be estimated using parallax measurements, yielding a value of 81.8 light-years (25.1 parsecs). This is a giant star with a stellar classification of K2 III. Although it is only 13% greater in mass than the Sun, it has reached a stage in its evolution where the atmosphere has expanded to about 12 times the Sun's radius and is radiating 63 times the luminosity of the Sun. Its outer envelope is relatively cool with an effective temperature of 4,467 K, giving it the orange hue typical of K-type stars. Like some other K-type giants, β Ophiuchi has been found to vary very slightly (0.02 magnitudes) in brightness. Cebalrai is a member of the thin disk population. It is following a low eccentricity orbit through the Milky Way galaxy that carries it between a distance of 27.3–30.9
    9.00
    1 votes
    114
    Epsilon Ursae Majoris

    Epsilon Ursae Majoris

    Epsilon Ursae Majoris (Epsilon UMa, ε Ursae Majoris, ε UMa) is the brightest star in the constellation Ursa Major (despite its Bayer designation being merely "epsilon"), and at magnitude 1.76 is the thirty-first brightest star in the sky. It has the traditional name Alioth. It is the star in the tail of the bear closest to its body, and thus the star in the handle of the Big Dipper closest to the bowl. It is also a member of the large and diffuse Ursa Major moving group. Historically, the star was frequently used in celestial navigation in the maritime trade, because it is listed as one of the 57 navigational stars. According to Hipparcos, Alioth is 81 light years (25 parsecs) from Earth. Its spectral type is A0p; the "p" stands for peculiar, as the spectrum of its light is characteristic of an Alpha2 Canum Venaticorum variable. Alioth, as a representative of this type, may harbor two interacting processes. First, the star's strong magnetic field separating different elements in the star's hydrogen 'fuel'. In addition, a rotation axis at an angle to the magnetic axis may be spinning different bands of magnetically-sorted elements into the line of sight between Alioth and the Earth.
    9.00
    1 votes
    115
    Gamma2 Caeli

    Gamma2 Caeli

    Gamma Caeli (γ Cae, γ Caeli) is a binary star in the constellation Caelum. It is approximately 334 light years from Earth. The primary component, γ Caeli A, is a yellow-white F-type giant with a mean apparent magnitude of +6.32. It is classified as a Delta Scuti type variable star and its brightness varies from magnitude +6.28 to +6.39 with a period of 3.25 hours. The companion star, γ Caeli B, has an apparent magnitude of +9.6 and is located 0.886 arcseconds from the primary and spectral type F2IV/V.
    9.00
    1 votes
    116
    31 Camelopardalis

    31 Camelopardalis

    31 Camelopardalis is an eclipsing spectroscopic binary in the constellation Camelopardalis. It is approximately 405 light years from Earth. The binary system is classified as a white A-type main sequence dwarf with a mean apparent magnitude of +5.20. Both component stars are detached main sequence stars which do not fill their Roche lobes. Because the components regularly eclipse each other, 31 Camelopardalis is classified as a variable star and its brightness varies from magnitude +5.12 to +5.29 with a period of 2.93 days, which is the orbital period of the binary.
    5.00
    5 votes
    117
    Cha 110913-773444

    Cha 110913-773444

    Cha 110913-773444 (sometimes abbreviated Cha 110913) is an astronomical object surrounded by what appears to be a protoplanetary disk. There is no consensus yet among astronomers whether to classify the object as a sub-brown dwarf (with planets) or a rogue planet (with moons). Cha 110913-773444 was discovered in 2004 by Kevin Luhman and others at Pennsylvania State University using the Spitzer Space Telescope and the Hubble Space Telescope, as well as two earthbound telescopes in Chile.
    6.67
    3 votes
    118
    Earth

    Earth

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Moon
    Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world, the Blue Planet, or by its Latin name, Terra. Earth formed approximately 4.54 billion years ago by accretion from the solar nebula, and life appeared on its surface within one billion years. The planet is home to millions of species, including humans. Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer, which together with Earth's magnetic field blocks harmful solar radiation, thus permitting formerly ocean-confined life to move safely to land. The physical properties of the Earth, as well as its geological history and orbit, have allowed life to persist. Estimates on how much longer the planet will to be able to continue to support life range from 500 million years, to as long as 2.3 billion years. Earth's crust is divided into several rigid segments, or tectonic plates, that migrate across the surface over periods
    6.67
    3 votes
    119
    HD 101930

    HD 101930

    HD 101930 is a dim 8th magnitude star located approximately 99 light years away in the constellation of Centaurus. It is an orange dwarf (spectral class K2V), somewhat dimmer and cooler than our Sun. In 2005, the discovery of a planet orbiting the star was announced. This is another discovery using the radial velocity method with the HARPS spectrograph.
    6.67
    3 votes
    120
    PSR B1620-26

    PSR B1620-26

    PSR B1620-26 is a binary star system located at a distance of 3,800 parsecs (12,400 light-years) in the globular cluster of Messier 4 (M4, NGC 6121) in the constellation of Scorpius. The system is composed of a pulsar (PSR B1620-26 A) and a white dwarf (WD B1620-26 or PSR B1620-26 B). As of 2000, the system is also confirmed to have an extrasolar planet orbiting the two stars. It is theorized that originally PSR B1620−26 A had another, lower mass white dwarf companion, which was ejected when the current PSR B1620−26 B interacted with the original binary system. At that time, PSR B1620−26 B was still a main sequence star, with its planet. Whereupon, the planet settled into orbit around both stars. The triple system is just outside the core of the globular cluster. The age of the cluster has been estimated to be about 12.2 billion years. Hence this is the age estimate for the birth of the planet, and two stars. There is a minor dispute about the proper nomenclature rules to use for this unusual star system. One side regards the A/B convention of naming binary stars as having priority, so that the pulsar is PSR B1620-26 A, the white dwarf companion is PSR B1620-26 B and the planet is
    6.67
    3 votes
    121
    Lambda Scorpii

    Lambda Scorpii

    Lambda Scorpii (λ Sco, λ Scorpii) is the second brightest star system in the constellation Scorpius, and one of the brightest stars in the nighttime sky. It has the Bayer designation λ despite being the second brightest in its constellation. It has the traditional name Shaula, which comes from the Arabic الشولاء al-šawlā´ meaning the raised [tail], as it is found in the tail of the scorpion (Scorpius). It is known as 尾宿八 (the Eighth Star of the Tail) in Chinese. Lambda Scorpii is a multiple star which was 300 mlight years away from the earth with three visible components. The first, Lambda Scorpii A, is classified as a B-type subgiant. The 15th magnitude Lambda Scorpii B has a separation of 42 arcseconds from component A, while the 12th magnitude Lambda Scorpii C is 95 arcseconds from A. It is not known whether or not these components are physically associated with component A. If they both were, B would be approximately 7500 Astronomical Units and C approximately 17,000 AU (0.27 light years) from A. Spectroscopic and interferometric observations have shown that A is actually a triple system consisting of two B-type stars and a pre–main sequence star. The primary star is also a
    5.75
    4 votes
    122
    69230 Hermes

    69230 Hermes

    • Orbits: Sun
    69230 Hermes is an Apollo, Mars- and Venus-crosser asteroid that passed Earth at about twice the distance of the Moon on October 30, 1937. It is named after the Greek god Hermes. At the time, this was the closest known approach of an asteroid to the Earth. Not until 1989 was a closer approach (by 4581 Asclepius) observed. At closest approach, Hermes was moving 5° per hour across the sky and reached 8th magnitude. It was discovered by Karl Reinmuth in images taken on October 28, 1937. Only four days of observations could be made before Hermes became too faint to be seen in the telescopes of the day. This was not enough to calculate an orbit, and Hermes was "lost" (see lost asteroids). It thus did not receive a number, but Reinmuth nevertheless named it after the Greek god Hermes. It was the only unnumbered but named asteroid, having only the provisional designation 1937 UB. On October 15, 2003, Brian A. Skiff of the LONEOS project made an asteroid observation that, when the orbit was calculated backwards in time (by Timothy B. Spahr, Steven Chesley and Paul Chodas), turned out to be a rediscovery of Hermes. The orbit is now well known, and Hermes has been assigned sequential number
    7.50
    2 votes
    123
    Alphard

    Alphard

    Alphard (α Hya, α Hydrae, Alpha Hydrae) is the brightest star in the constellation Hydra. The name Alphard is from the Arabic الفرد (al-fard), "the solitary one", there being no other bright stars near it. It was also known as the "backbone of the Serpent" to the Arabs. In ancient China it formed part of an asterism called the "red bird". The European astronomer Tycho Brahe dubbed it Cor Hydræ, the heart of the snake. In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Soheil al Fard, which was translated into Latin as Soheil Solitarius, meaning the bright solitary one. In Chinese, 星宿 (Xīng Sù), meaning Star (asterism), refers to an asterism consisting of Alphard, τ Hydrae, τ Hydrae, ι Hydrae, 26 Hydrae, 27 Hydrae, HD 82477 and HD 82428. Consequently, Alphard itself is known as 星宿一 (Xīng Sù yī, English: the First Star of Star.) Alphard has three times the mass of the Sun. The estimated age of this star is 420 million years and it has evolved away from the main sequence to become a giant star with a spectral classification of K3 and luminosity class between II and III. The angular diameter of this star has been measured using long
    7.50
    2 votes
    124
    Comet Kohoutek

    Comet Kohoutek

    Comet Kohoutek, formally designated C/1973 E1, 1973 XII, and 1973f, was first sighted on 7 March 1973 by Czech astronomer Luboš Kohoutek. It attained perihelion on 28 December that same year. Comet Kohoutek is a long-period comet; its previous apparition was about 150,000 years ago, and its next apparition will be in about 75,000 years. At its apparition in 1973 it had a hyperbolic trajectory (e > 1) due to gravitational perturbations from giant planets. Due to its path, scientists theorized that Kohoutek was an Oort-cloud object. As such, it was believed likely that this was the comet's first visit to the inner Solar System, which would result in a spectacular display of outgassing. Infrared and visual telescopic study have led many scientists to conclude, in retrospect, that Kohoutek is actually a Kuiper-belt object, which would account for its apparent rocky makeup and lack of outgassing. Before its close approach, Kohoutek was hyped by the media as the "comet of the century". However, Kohoutek's display was considered a let-down, possibly due to partial disintegration when the comet closely approached the sun prior to Earth flyby. This appartion was considered its first
    7.50
    2 votes
    125
    Epsilon Cassiopeiae

    Epsilon Cassiopeiae

    Epsilon Cassiopeiae (ε Cas, ε Cassiopeiae) is a star system in the constellation Cassiopeia. It has the traditional name Segin. With an apparent visual magnitude of 3.4, this is one of the brightest stars in the constellation. The distance to this star has been determined directly using parallax measurements, yielding a value of around 390–430 light-years (120–130 parsecs). This is a giant star with a stellar classification of B3 III, indicating that is has exhausted the hydrogen at its core and entered a later evolutionary stages of its lifetime. Cote et al. (2003) indicate that it displays the spectral properties of a Be star, even though it is not categorized as such. The presence of emission lines in the spectrum indicates the presence of a circumstellar shell of gas that has been thrown off by the star. The outer atmosphere of Epsilon Cassiopeiae has an effective temperature of 15,174 K, giving it the blue-white hue of a B-type star. The interferometer-measured angular diameter is 0.43 milliarcseconds. At the estimated distance of this star, this yields a physical size of roughly 6 times the radius of the Sun. Observation of this star during the Hipparcos mission suggest that
    7.50
    2 votes
    126
    Epsilon Pegasi

    Epsilon Pegasi

    Epsilon Pegasi (ε Peg, ε Pegasi) is the brightest star in the northern constellation of Pegasus. It has the traditional name Enif. The name "Enif" is derived from the Arabic word for nose, due to its position as the muzzle of Pegasus. With an apparent visual magnitude of 2.4, this is a second-magnitude star that is readily visible to the naked eye. The distance to this star can be estimated using parallax measurements from the Hipparcos astrometry satellite, yielding a value of around 690 light-years (210 parsecs). In Chinese, 危宿 (Wēi Sù), meaning Rooftop (asterism), refers to an asterism consisting of ε Pegasi, α Aquarii and θ Peg. Consequently, ε Pegasi itself is known as 危宿三 (Wēi Sù sān, English: the Third Star of Rooftop.) This is an evolved star that has entered the supergiant stage, as indicated by the stellar classification of K2 Ib. It is estimated to be 12 times the Sun's mass. The measured angular diameter of this star, after correction for limb darkening, is 8.17 ± 0.09 mas. At the estimated distance of this star, this yields an enormous physical size of about 185 times the radius of the Sun. From this expanded envelope, it is radiating roughly 5,000 times the luminosity
    7.50
    2 votes
    127
    Eta Boötis

    Eta Boötis

    Eta Boötis (η Boo, η Boötis) is a star in the constellation Boötes. It has the traditional names Muphrid and Saak, and the Flamsteed designation 8 Boötis. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. The name Muphrid is from the Arabic مفرد الرامح mufrid ar-rāmiħ "the (single) one of the lancer". In Chinese, 右攝提 (Yòu Niè Dī), meaning "the Right Conductor", refers to an asterism consisting of Eta Boötis, Tau Boötis and Upsilon Boötis. Consequently, Eta Boötis itself is known as 右攝提一 (Yòu Niè Dī yī, English: the First Star of the Right Conductor.) In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Ramih al Ramih (رمح الرامح - rumḥ al rāmiḥ), which was translated into Latin as Lancea Lanceator, possibly meaning the lance of the lancer. This star is a subgiant that has begun the process of evolving from a main sequence star into a red giant. It has about 1.7 times the mass of the Sun and 2.7 times the Sun's radius. The estimated age of this star is about 2.7 billion years. Based on its spectra, Eta Boötis has a significant excess of elements heavier than helium. In
    7.50
    2 votes
    128
    Iota Cassiopeiae

    Iota Cassiopeiae

    Iota Cassiopeiae (ι Cas, ι Cassiopeiae) is a star system in the constellation Cassiopeia. It is approximately 141.6 light years from Earth. The primary component, ι Cassiopeiae A, is a white A-type main sequence dwarf with a mean apparent magnitude of +4.64. It is classified as an α² Canum Venaticorum type variable star and the brightness of the system varies from magnitude +4.45 to +4.53 with a period of 1.74 days. Component A is a spectroscopic binary. Its unresolved companion has an orbital period of 52.4 years and is separated from the primary by 0.113 arcseconds, or at least 5 AU. The second astrometric component, ι Cassiopeiae B, is a yellow-white F-type main sequence dwarf with an apparent magnitude of +6.89. It is 2.27 arcseconds, or at least 100 AU, from the primary. It has an orbital period of 840 years. The third astrometric component, ι Cassiopeiae C, is a yellow G-type dwarf, with an apparent magnitude of +8.40. It is 7.3 arcseconds (at least 300 AU) from the primary.
    7.50
    2 votes
    129
    Xi Scorpii

    Xi Scorpii

    Xi Scorpii (ξ Sco, ξ Scorpii) is a star system in the constellation Scorpius. It was also 51 Lib. The Xi Scorpii system consists of at least five stars in two groups separated by 4.67 arcminutes (or 0.08°) on the sky, corresponding to a distance of at least 8000 astronomical units (AU). The brighter group contains Xi Scorpii A, B, and C. A and B are both yellow-white F-type stars. A is a slightly brighter and warmer magnitude +4.8 subgiant, while B is a magnitude +5.1 main sequence dwarf. They are separated by 0.76 arcseconds, or at least 21 AU, roughly a Sun–Uranus distance, and orbit around a common centre once every 46 years. The magnitude +7.6 Xi Scorpii C orbits this pair at ten times the distance, having a separation of 7.6 arcseconds. The second group contains Xi Scorpii D and E. Both D and E are K-type stars, which are separated by 11.5 arcseconds, more than 320 AU. Xi Scorpii also possesses a sixth component, the 11th magnitude Xi Scorpii F, located 81 arcseconds from D. It is not known to be gravitationally bound to the other five components. Xi Scorpii was a latter designation of 51 Librae.
    7.50
    2 votes
    130
    Beta Gruis

    Beta Gruis

    Beta Gruis (β Gruis, β Gru) is the second brightest star in the southern constellation of Grus. It was once considered the rear star in the tail of the constellation of the (Southern) Fish: it, with α, δ, θ. ι, and λ Gru, belonged to Piscis Austrinus in traditional Arabic astronomy. This is a red giant star with an estimated mass of about 2.4 times that of the Sun and a surface temperature of approximately 3,480 K, just over half the surface temperature of the Sun. This low temperature accounts for the dull red color of an M-type star. The total luminosity is about 2,500 times that of the Sun, and it has estimated 180 times the Sun's radius. Beta Gruis is a type semiregular variable (SRb) star that varies in magnitude by about 0.4. It varies between intervals when it displays regular changes with a 37 day periodicity and times when it undergoes slow irregular variability. Beta Gruis played a crucial part in Perth Observatory's tracking of comet 2000 WM1 LINEAR in December 2001.
    5.50
    4 votes
    131
    29P/Schwassmann-Wachmann

    29P/Schwassmann-Wachmann

    Comet 29P/Schwassmann–Wachmann, also known as Schwassmann–Wachmann 1, was discovered on November 15, 1927, by Arnold Schwassmann and Arno Arthur Wachmann at the Hamburg Observatory in Bergedorf, Germany. It was discovered photographically, when the comet was in outburst and the magnitude was about 13. Precovery images of the comet from March 4, 1902, were found in 1931 and showed the comet at 12th magnitude. The comet is unusual in that while normally hovering at around 16th magnitude, it suddenly undergoes an outburst. This causes the comet to brighten by 1 to 4 magnitudes. This happens with a frequency of 7.3 outbursts per year, fading within a week or two. The magnitude of the comet has been known to vary from 19th magnitude to 9th magnitude, a ten thousand-fold increase in brightness, during its brightest outbursts. Highly changing surface processes are suspected to be responsible for the observed behavior. The comet is thought to be a member of a relatively new class of objects called "centaurs", of which at least 80 are known. These are small icy bodies with orbits between those of Jupiter and Neptune. Astronomers believe that centaurs are recent escapees from the Kuiper
    6.33
    3 votes
    132
    Deneb

    Deneb

    Deneb (α Cyg, α Cygni, Alpha Cygni) is the brightest star in the constellation Cygnus and one of the vertices of the Summer Triangle. It is the 19th brightest star in the night sky, with an apparent magnitude of 1.25. A blue-white supergiant, Deneb is also one of the most luminous nearby stars. However, its exact distance (and hence luminosity) has been difficult to calculate, so it is anywhere between 54,000 and 196,000 times as luminous as the sun. Other names include Arided and Aridif, but these have fallen out of use. Deneb lies at a vertex of a widely spaced asterism called the Summer Triangle, the other two members of which are the zero-magnitude stars Vega in the constellation Lyra and Altair in Aquila. This formation is the approximate shape of a right triangle, with Deneb located at one of the acute angles. The Summer Triangle is recognizable in the northern skies for there are few other bright stars in its vicinity. Deneb's absolute magnitude is currently estimated as −8.4, placing it among the most luminous stars known, with an estimated luminosity nearly 200,000 times that of our Sun. This is towards the upper end of various published values over the last few
    6.33
    3 votes
    133
    Eta Canis Majoris

    Eta Canis Majoris

    Eta Canis Majoris (η CMa, η Canis Majoris) is a star in the constellation Canis Major. It has the traditional name Aludra. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. The name Aludra originates from the Arabic: عذرا al-‘aðrā "the virgin". This star, along with ε CMa (Adhara), δ CMa (Wezen) and ο CMa (Thanih al Adzari), were Al ʽAdhārā (ألعذاري), the Virgins. In Chinese, 弧矢 (Hú Shǐ), meaning Bow and Arrow, refers to an asterism consisting of η Canis Majoris, δ Canis Majoris, HD 63032, HD 65456, ο Puppis, k Puppis, ε Canis Majoris, κ Canis Majoris and π Puppis. Consequently, δ Canis Majoris itself is known as 弧矢二 (Hú Shǐ èr, English: the Second Star of Bow and Arrow.) Aludra shines brightly in the skies in spite of a large distance from Earth due to being intrinsically many times brighter (absolute magnitude) than the Sun. A blue supergiant, Aludra has only been around a fraction of the time our Sun has, yet is already in the last stages of its life. It is still expanding and may become a red supergiant, or perhaps has already passed that phase, but in either case it will become a supernova within the next
    6.33
    3 votes
    134
    HD 209458

    HD 209458

    HD 209458 is an 8th magnitude star in the constellation Pegasus. It is very similar to our Sun, and it is classified as a yellow dwarf (spectral class G0 V). Because it is located at a distance of about 150 light years, it is not visible to the unaided eye. With good binoculars or small telescope it should be easily detectable. In 1999 two teams working independently (one team consisted of astronomers at the Geneva Observatory, the Harvard-Smithsonian Center for Astrophysics, and the Wise Observatory; the second group was the California and Carnegie Planet Search team) discovered an extrasolar planet orbiting the star by using the radial velocity planet search method. Soon after the discovery, separate teams led by David Charbonneau and Gregory W. Henry were able to detect a transit of the planet across the surface of the star making it the first known transiting extrasolar planet. The planet received the designation HD 209458 b. Because the planet transits the star, the star is dimmed by about 2% every 3.5 days making it an extrinsic variable. The variable star designation for HD 209458 is V376 Pegasi. It is the prototype of the variable class "EP" in the General Catalogue of
    6.33
    3 votes
    135
    Uranus

    Uranus

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Ariel
    Uranus is the seventh planet from the Sun. It has the third-largest planetary radius and fourth-largest planetary mass in the Solar System. It is named after the ancient Greek deity of the sky Uranus (Ancient Greek: Οὐρανός), the father of Cronus (Saturn) and grandfather of Zeus (Jupiter). Though it is visible to the naked eye like the five classical planets, it was never recognized as a planet by ancient observers because of its dimness and slow orbit. Sir William Herschel announced its discovery on March 13, 1781, expanding the known boundaries of the Solar System for the first time in modern history. Uranus was also the first planet discovered with a telescope. Uranus is similar in composition to Neptune, and both are of different chemical composition than the larger gas giants, Jupiter and Saturn. Astronomers sometimes place them in a separate category called "ice giants". Uranus's atmosphere, while similar to Jupiter's and Saturn's in its primary composition of hydrogen and helium, contains more "ices" such as water, ammonia and methane, along with traces of hydrocarbons. It is the coldest planetary atmosphere in the Solar System, with a minimum temperature of 49 K (−224 °C).
    6.33
    3 votes
    136
    Venus

    Venus

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it has been referred to by ancient cultures as the Morning Star or Evening Star. Venus is classified as a terrestrial planet and is sometimes called Earth's "sister planet" owing to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). However, it has been shown to be very different from Earth in other respects. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. It has the densest atmosphere of the four terrestrial planets, consisting mostly of carbon dioxide. The atmospheric pressure at the
    6.33
    3 votes
    137
    773 Irmintraud

    773 Irmintraud

    • Orbits: Sun
    773 Irmintraud is a minor planet that orbits the Sun between the planets Mars and Jupiter. Discovered by German astronomer Franz Kaiser at Heidelberg, Germany, on December 22, 1913, the planetoid was named for Irmtraud, an old German woman's name that appears frequently in old songs and sagas. This D-type asteroid's previous designation was 1913 TV. The 773 Irmintraud asteroid is a likely source of the Tagish Lake meteorite which landed in Canada on January 18, 2000. On December 22, 1913, German astronomer Franz Kaiser discovered 773 Irmintraud at Heidelberg, Germany. In 1992, Larry A. Lebofsky and colleagues published an article in which they noted that "unaltered asteroids are thought to represent the raw materials available for terrestrial planet formation and so are important to our understanding of the origin and evolution of the Solar System." Since at least 1980, it was believed that D-type asteroids were unaltered asteroids, ultraprimitive in composition and composed largely of hydrated silicates and organic material. However, in analyzing the spectra of 773 Irmintraud for the water of hydration band (the 3-µm absorption feature of hydrated silicates), Lebofsky discovered
    8.00
    1 votes
    138
    Beta Arietis

    Beta Arietis

    Beta Arietis (β Ari, β Arietis) is a binary star system in the constellation Aries, marking the Ram's second horn. It has the traditional name Sheratan (or Sharatan, Sheratim), and the Flamsteed designation 6 Arietis. The traditional name, in full Al Sharatan, is from the Arabic الشراطان aš-šarāţān "the two signs", a reference to the star having marked the northern vernal equinox together with Gamma Arietis several thousand years ago. In Chinese, 婁宿 (Lóu Su), meaning Bond (asterism), refers to an asterism consisting of β Arietis, γ Arietis and α Arietis. Consequently, β Arietis itself is known as 婁宿一 (Lóu Su yī, English: the First Star of Bond). Beta Arietis has an apparent visual magnitude of 2.66. Based on parallax measurements, it is located at a distance of 59.6 light-years (18.3 parsecs) from Earth. This is a spectroscopic binary star system consisting of a pair of stars orbiting around each other with a separation that can not currently be resolved with a conventional telescope. However, the pair have been resolved using the Mark III Stellar Interferometer at the Mount Wilson Observatory. This allows the orbital elements to be computed, as well as the individual masses of the
    8.00
    1 votes
    139
    Comet Arend-Roland

    Comet Arend-Roland

    • Orbits: Sun
    Comet Arend–Roland was discovered on November 8, 1956, by Belgian astronomers Sylvain Arend and Georges Roland on photographic plates. As the eighth comet found in 1956, it was named Arend–Roland 1956h after its discoverers. Because it was the third comet to pass through perihelion during 1957, it was then renamed 1957 III. Finally, it received the standard IAU designation C/1956 R1 (Arend–Roland), with the 'C/' indicating it was a non-periodic comet and the R1 showing it was the first comet reported as discovered in the half-month designated by R. The last is equivalent to the period September 1–15. In November 1956, a double astrograph at the Uccle Observatory in Brussels was being used for routine investigation of minor planets. On November 8, 1956, the Belgian astronomers Sylvain Arend and Georges Roland discovered a comet on their photographic plates. At that time the comet was at visual magnitude 10, with a strong central condensation and a short tail. The early discovery of this comet allowed observing programs and equipment to be prepared well in advance. The orbital elements for this comet were computed by Michael P. Candy, who predicted perihelion passage on April 8,
    8.00
    1 votes
    140
    Comet West

    Comet West

    Comet West formally designated C/1975 V1, 1976 VI, and 1975n, was a spectacular comet, sometimes considered to qualify for the status of "great comet". It was discovered photographically by Richard M. West, of the European Southern Observatory, on August 10, 1975. The comet came to perihelion (closest approach to the Sun) on February 25, 1976. During perihelion the comet had a minimum solar elongation of 6.4° and as a result of forward scattering reached a peak brightness of -3. From February 25th through the 27th, observers reported that the comet was bright enough to study during full daylight. Despite its spectacular appearance, Comet West went largely unreported in the popular media. This was partly due to the relatively disappointing display of Comet Kohoutek in 1973, which had been widely predicted to become extremely prominent: scientists were wary of making predictions that might raise public expectations. With a nearly parabolic trajectory, estimates for the orbital period of this comet have varied from 254,000 to 558,000 years, and even as high as 6.5 million years. Computing the best-fit orbit for this long-period comet is made more difficult since it underwent a
    8.00
    1 votes
    141
    Delta Scuti

    Delta Scuti

    Delta Scuti (δ Sct, δ Scuti) is a giant star in the southern constellation Scutum. With an apparent visual magnitude of 4.72, it is the fifth brightest star in this small and otherwise undistinguished constellation. Analysis of the parallax measurements made during the Hipparcos mission place this star at a distance of about 202 light-years (62 parsecs) from Earth. Delta Scuti is the prototype of the Delta Scuti type variable stars. It is a high-amplitude δ Scuti type pulsator with light variations of about 0.15 minutes. The peculiar chemical abundances of this star are similar to those of Am stars. In 1900, William W. Campbell and William H. Wright used the Mills spectrograph at the Lick Observatory to determine that this star has a variable radial velocity. The 0.19377 day period of this variability as well as 0.2 magnitude changes in luminosity demonstrated in 1935 that the variability was intrinsic, rather than being the result of a spectroscopic binary. In 1938, a secondary period was discovered and a pulsation theory was proposed to model the variation. Since then, observation of Delta Scuti has shown that it pulsates in multiple discrete radial and non-radial modes. The
    8.00
    1 votes
    142
    Delta Ursae Majoris

    Delta Ursae Majoris

    Delta Ursae Majoris (Delta UMa, δ Ursae Majoris, δ UMa) is the Bayer designation for a star in the northern circumpolar constellation of Ursa Major. It has the traditional names Megrez /ˈmɛɡrɛz/, and Kaffa. Megrez has an apparent magnitude of +3.3, making it the dimmest of the seven stars in the Big Dipper asterism. Parallax measurements yield a distance estimate of 58.4 light-years (17.9 parsecs) from Earth. Megrez has 63% more mass of the Sun and is about 1.4 times the Sun's radius. It has a stellar classification of A3 V, which means it is an A-type main sequence star that is generating energy at its core through the nuclear fusion of hydrogen. It shines at 14 times the luminosity of the Sun, with this energy being emitted from its outer envelope at an effective temperature of 9,480 K. This gives it the white hue typical of an A-type star. This star has an excess emission of infrared radiation, indicating the presence of circumstellar matter. This forms a debris disk around an orbital radius of 16 Astronomical Units from the star. This radius is unusually small for the estimated age of the disk, which may be explained by drag from the Poynting–Robertson effect causing the dust
    8.00
    1 votes
    143
    Gamma1 Caeli

    Gamma1 Caeli

    Gamma Caeli (γ Cae, γ Caeli) is a double star in the constellation Caelum. It is approximately 185 light years from Earth. The brighter component is an orange K-type giant with an apparent magnitude of +4.55. The companion is an eighth magnitude star located 3.1 arcseconds away.
    8.00
    1 votes
    144
    Lambda Caeli

    Lambda Caeli

    Lambda Caeli, (λ Cae, λ Caeli), also known as HD 1989 is an optical double star in the constellation Caelum. The components are Lambda A and Lambda B Caeli. Lambda A, also known as HD 32831, is an K3III orange K-type giant with an apparent magnitude of +4.55. It is approximately 57 pc from the Sun. Lambda B, also known as, HD 32846 and V*X Caeli has an apparent magnitude of 6.34, and is 102 pc from the Sun. It is an F1III, a yellowish-white F-type giant. It is a Delta Scuti variable star.
    8.00
    1 votes
    145
    Pluto

    Pluto

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Hydra
    Pluto, formal designation 134340 Pluto, is the second-most-massive known dwarf planet in the Solar System (after Eris) and the tenth-most-massive body observed directly orbiting the Sun. Originally classified as the ninth planet from the Sun, Pluto was recategorized as a dwarf planet and plutoid owing to the discovery that it is only one of several large bodies within the Kuiper belt. Like other members of the Kuiper belt, Pluto is composed primarily of rock and ice and is relatively small, approximately one-sixth the mass of the Earth's Moon and one-third its volume. It has an eccentric and highly inclined orbit that takes it from 30 to 49 AU (4.4–7.4 billion km) from the Sun. This causes Pluto to periodically come closer to the Sun than Neptune. As of 2011, it is 32.1 AU from the Sun. From its discovery in 1930 until 2006, Pluto was classified as a planet. In the late 1970s, following the discovery of minor planet 2060 Chiron in the outer Solar System and the recognition of Pluto's relatively low mass, its status as a major planet began to be questioned. In the late 20th and early 21st centuries, many objects similar to Pluto were discovered in the outer Solar System, notably the
    8.00
    1 votes
    146
    Theta Apodis

    Theta Apodis

    Theta Apodis (θ Aps, θ Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. It is a variable star with a mean apparent visual magnitude of 5.7, which, according to the Bortle Dark-Sky Scale, means it is a faint star but visible to the naked eye from dark suburban skies. The distance to Theta Apodis is approximately 370 light-years (110 parsecs), based upon parallax measurements made from the Hipparcos spacecraft. This is an evolved red giant that is currently on the asymptotic giant branch, with a stellar classification of M7 III. It is a semiregular pulsating variable and its brightness changes over a range of 0.56 magnitudes with a period of 119 days. It is losing mass at the rate of 1.1 × 10 times the mass of the Sun per year through its stellar wind. Dusty material ejected from this star is interacting with the surrounding interstellar medium, forming a bow shock as the star moves through the galaxy. The stand-off distance for this front is located at about 0.134 ly (0.041 pc) from Theta Apodis. Theta Apodis has been identified as an astrometric binary, indicating that it has an orbiting companion that causes gravitational perturbation
    8.00
    1 votes
    147
    Westerlund 2

    Westerlund 2

    Westerlund 2 is a young massive obscured star cluster with an estimated age of about one or two million years. It contains some of the hottest, brightest, and most massive stars known. The cluster contains a dozen of O stars, of which at least three are eclipsing binaries, many pre–main sequence stars and two Wolf-Rayet Stars: the binary WR20a and the single star WR20b, all of spectral type WN6ha. They are probably not actually Wolf-Rayet stars, i.e. they are core hydrogen burning stars, just like the sun. Due to their large mass loss rate they appear to be Wolf Rayet stars. It was shown recently that the core of the cluster contains several examples of rare very hot stars (Rauw et al. 2007, A&A, 463, 981). Just outside the cluster a massive eclipsing binary WR20a is found at 30 arcseconds (about 1.1 pc in projection), the bright yellow spot just on the lower right side of the cluster center. As its name indicates, the Westerlund 2 cluster was discovered by Bengt Westerlund in the sixties (Westerlund 1961, PASP, 73, 51 and 1968, ApJ, 154, L67 see http://vizier.u-strasbg.fr/cgi-bin/Dic-Simbad?Cl%20Westerlund ) but its stellar content was assessed only in the last years (Moffat et
    8.00
    1 votes
    148
    Zeta Arietis

    Zeta Arietis

    Zeta Arietis (ζ Ari, ζ Arietis) is the Bayer designation for a star in the northern constellation of Aries. It is dimly visible to the naked eye with an apparent visual magnitude of +4.89. Based upon an annual parallax shift of 12.44 mas, the distance to this star is 260 ± 20 light-years (80 ± 6.1 parsecs). This is an A-type main sequence star with a stellar classification of A1 V. It has a high rate of rotation with a projected rotational velocity of 133 km/s. The star is shining at an effective temperature of 9,500 K, giving it the characteristic white-hued glow of an A-type star. This star, along with δ Ari, ε Ari, π Ari, and ρ Ari, were Al Bīrūnī's Al Buṭain (ألبطين), the dual of Al Baṭn, the Belly. According to the catalogue of stars in the Technical Memorandum 33-507 - A Reduced Star Catalog Containing 537 Named Stars, Al Buṭain were the title for five stars : δ Ari as Botein, π Ari as Al Buṭain I, ρ Ari as Al Buṭain II, ε Ari as Al Buṭain III dan ζ Ari as Al Buṭain IV. In Chinese, 天陰 (Tiān Yīn), meaning Yin Force, refers to an asterism consisting of ζ Arietis, 63 Arietis, δ Arietis, τ Arietis and 65 Arietis. Consequently, ζ Arietis itself is known as 天陰二 (Lóu Su èr, English:
    8.00
    1 votes
    149
    3908 Nyx

    3908 Nyx

    • Orbits: Sun
    3908 Nyx is an Amor and Mars-crosser asteroid. It was discovered by Hans-Emil Schuster on August 6, 1980, and is named after Nyx, the Greek goddess of the night, after which Pluto's moon Nix is also named. It is 1–2 km in diameter and is a V-type asteroid, meaning that it may be a fragment of the asteroid 4 Vesta. In 2000, radar observations conducted at the Arecibo and Goldstone observatories produced a model of Nyx's shape; the asteroid can best be described as spherical but with many protruding lumps. To avoid confusion with 3908 Nyx, Pluto's moon Nix was changed from the initial proposal of the classical spelling Nyx, to Nix.
    7.00
    2 votes
    150
    78P/Gehrels

    78P/Gehrels

    78P/Gehrels, also known as Gehrels 2, is a periodic comet in the Solar System. Comet 78P/Gehrels' aphelion (furthest distance from the Sun) of 5.4AU is in the zone of control of the giant planet Jupiter and the orbit of the comet is frequently perturbed by Jupiter. On September 15, 2029, the comet will pass within 0.018 AU (2.7 million kilometers) of Jupiter and be strongly perturbed. By the year 2200, the comet will have a centaur-like orbit with a perihelion (closest distance to the Sun) near Jupiter. This outward migration from a perihelion of 2AU to a perihelion of ~5AU could cause the comet to go dormant.
    7.00
    2 votes
    151
    Alpha Arietis

    Alpha Arietis

    Alpha Arietis (α Ari, α Arietis) is the Bayer designation for the brightest star in the northern zodiacal constellation of Aries. It has the traditional name Hamal, which comes from the Arabic phrase for "head of the ram", and the Flamsteed designation of 13 Arietis. With an apparent visual magnitude of 2.0, it among the brightest stars in the night sky. Based upon parallax measurements made with Hipparcos astrometry satellite, α Arietis is about 65.8 light-years (20.2 parsecs) from Earth. It is a giant star that may host an orbiting planet with a mass greater than Jupiter. The spectrum of this star matches a stellar classification of K2 III Ca-1, with the luminosity class of III indicating that it is an evolved giant star that has exhausted the supply of hydrogen at its core and is now on the red giant branch. The 'Ca-1' portion of the classification indicates that it shows weaker than normal lines of calcium in its spectrum. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It is estimated to have about 50% more mass than the Sun, while interferometric measurements show it to be 15 times larger in diameter.
    7.00
    2 votes
    152
    Alpha Pegasi

    Alpha Pegasi

    Alpha Pegasi (α Peg, α Pegasi) is the third brightest star in the constellation Pegasus and one of the four stars in the asterism known as the Great Square of Pegasus. It has the traditional name Marko (or MT), which comes from an Arabic word مركب markab, "the saddle of the horse", or is mistranscription of Mankib comes from an Arabic phrase منكب الفرس Mankib al-Faras, "(the Star of) the Shoulder (of the Constellation) of the Horse" for β Pegasi. Marko aka MT has a stellar classification of B9 III, indicating that it is a B-type giant star that has exhausted the hydrogen at its core and has evolved beyond the main sequence. It is rotating rapidly, with a projected rotational velocity of 125 km/s giving a lower bound on the azimuthal velocity along the star's equator. The effective temperature of the photosphere is nearly 10,000 K and the star has expanded to nearly five times the radius of the Sun.
    7.00
    2 votes
    153
    Beta Canis Minoris

    Beta Canis Minoris

    Beta Canis Minoris (β CMi, β Canis Minoris) is a star in the constellation of Canis Minor. In the night sky it is notable for its proximity to the prominent star Procyon. It has the traditional name Gomeisa, which comes from the Arabic al-ghumaisa’ "the bleary-eyed (woman)", short for مرزم الغميصاء mirzam al-ghumaisa’ "girdle of the bleary-eyed one". In Arabic, the short form would be identical with the name of Procyon. In Chinese, 南河 (Nán Hé), meaning South River, refers to an asterism consisting of β Canis Minoris, Procyon and ε Canis Minoris. Consequently, β Canis Minoris itself is known as 南河二 (Nán Hé èr, English: the Second Star of South River.) From parallax measurements, the distance to this star is about 162 light-years (50 parsecs). It has an apparent visual magnitude of 2.89, making it easily visible to the naked eye. Beta Canis Minoris has about 3.5 times the Sun's mass and is rotating rapidly with a projected rotational velocity of 210 km s, which gives a lower bound on the azimuthal rotational velocity along the star's equator. The actual rotation rate may be about once per day. The stellar classification of this star is B8 Ve. A luminosity class V star belongs on the
    7.00
    2 votes
    154
    Chi Cygni

    Chi Cygni

    Chi Cygni (χ Cyg, χ Cygni) is a variable star of the Mira type in the constellation Cygnus. Chi Cygni shows one of the largest variations in magnitude known. Typically it brightens and fades from 5th to 13th magnitude. The average period of this brightness fluctuation is 407 days. Observed extremes were 3.3 and 14.3 respectively. Thus Chi Cygni is visible at its minimum only with telescopes larger than 30 centimeters, while at maximum brightness is easily visible to the naked eye. Its distance is approximately 345 light years. The astronomer Gottfried Kirch discovered its variability in 1686. Thomas Dick, LL.D, writes: "The period of this star has been settled by Maraldi and Cassini at 405 days; but from a mean of the observations of Mr. Pigot, it appears to be only 392, or at most 396-7/8 days. "The particulars relating to it are, "It is situated in the neck [of the Swan constellation], and nearly equi-distant from Beta and Gamma, and south by west from Deneb, at the distance of about twelve degrees, and is marked Chi."
    7.00
    2 votes
    155
    Chi Ursae Majoris

    Chi Ursae Majoris

    Chi Ursae Majoris (Chi UMa, χ Ursae Majoris, χ UMa) is a star in the constellation Ursa Major. It has the traditional names Alkafzah, Alkaphrah, and El Koprah. Chi Ursae Majoris is an orange K-type giant with an apparent magnitude of +3.69. It is approximately 196 light years from Earth. This star has 20.8 ± 0.8 times the radius of the Sun. In Chinese astronomy, Alkafzah is called Tae Yang Show, "the Sun Governor". The name was possibly derived from the word 太陽守, Pinyin: Tàiyángshǒu, meaning Guard of the Sun, because this star is marking itself and stand alone in Guard of the Sun asterism, Purple Forbidden enclosure (see : Chinese constellation). The Spiral Galaxy in Ursa Major, NGC 3877 (= H I.201), type Sc, is best found from Chi Ursae Majoris, which is almost exactly 15 arc minutes north of the galaxy.
    7.00
    2 votes
    156
    Delta Leonis

    Delta Leonis

    Delta Leonis (δ Leo, δ Leonis) is a star in the zodiac constellation of Leo. It has the traditional names Zosma (or Zozma) and Duhr. Rare spellings include Zozca, Zosca, Zubra, and Dhur. The name Zosma means girdle in ancient Greek, referring to the star's location in its constellation, on the hip of the lion. Based upon parallax measurements, it lies at a distance of about 58.4 light-years (17.9 parsecs) from the Earth. Zosma is a relatively ordinary main sequence star with a stellar classification of A4 V, making it is somewhat larger and hotter than the Sun. It is a fairly well-studied star, allowing relatively accurate measurements of its age and size. The radius of the star, as measured directly using an interferometer, is about 214% of the Sun's radius and it is emitting more than 15 times as much luminosity as the Sun. The energy is being emitted from the outer envelope with an effective temperature 8,296 K, giving it the white hue characteristic of an A-type star. Having a larger mass than the Sun it will have a shorter lifespan, and in another 600 million years or so will swell into an orange or red giant star before decaying quietly into a white dwarf. This star is
    7.00
    2 votes
    157
    Delta2 Canis Minoris

    Delta2 Canis Minoris

    Delta Canis Minoris (δ CMi, δ Canis Minoris) is a star in the constellation Canis Minor. It is one of three stars that share the Bayer designation Delta Canis Minoris in Johann Bayer's 1603 Uranometria atlas of bright stars. The Flamsteed designation for this star is 8 Canis Minoris, indicating it is the eighth star in the constellation Canis Minoris listed in John Flamsteed's 1712 star catalogue. As of 2008, no companion has been discovered orbiting δ Canis Minoris; it appears to be a solitary star. The apparent magnitude of 5.589 means this star is visible to the naked eye, although it is faint and requires a dark sky to view. Based upon parallax measurements, this star is about 136 light years distant from the Earth. This star is rotating rapidly; the projected rotational velocity is 117.6 km/s, which means that the equator of this star is rotating at this velocity or greater. By comparison, the Sun is a slow rotator with an equatorial azimuthal velocity of 2 km/s. δ Canis Minoris has a stellar classification of F2 V, indicating that this is an F-type main-sequence star that is generating energy at its core through thermonuclear fusion of hydrogen. The effective temperature of
    7.00
    2 votes
    158
    Gamma Ursae Majoris

    Gamma Ursae Majoris

    Gamma Ursae Majoris (Gamma UMa, γ Ursae Majoris, γ UMa) is a star in the constellation Ursa Major It has the traditional name Phad, or Phecda. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Based upon parallax measurements with the Hipparcos astrometry satellite, it is located at distance of around 83.2 light-years (25.5 parsecs). It is more familiar to most observers in the northern hemisphere as the lower-left star forming the bowl of the Big Dipper, together with Dubhe (upper-right), Merak (lower-right) and Megrez (upper-left). Along with four other stars in this well-known asterism, Phecda forms an actual loose, association of stars known as the Ursa Major moving group. Like the other stars in the group, it is a main sequence star not unlike our Sun, although somewhat hotter, brighter and larger. Gamma Ursae Majoris is an Ae star, which is surrounded by an envelope of gas that is adding emission lines to the spectrum of the star; hence the 'e' suffix in the stellar classification of A0 Ve. It has 2.6 times the mass of the Sun, three times the Sun's radius, and an effective temperature of 9,355 K in its
    7.00
    2 votes
    159
    Io

    Io

    • Orbits: Jupiter
    Io  /ˈaɪ.oʊ/ is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres (2,263 mi), the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus. With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of the moon's silicate crust. Some of these peaks are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System, which are mostly composed of water-ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost. Io's
    7.00
    2 votes
    160
    Celaeno

    Celaeno

    Celaeno (Celeno or 16 Tauri) is a star in the constellation Taurus and a member of the Pleaides open cluster of stars. Celaeno is sometimes called the Lost Pleiad, a name alluded to in a poem by Alfred Austin. Star gazers often only see six of the seven Pleiades sisters with the unaided eye because Celaeno, with an apparent magnitude of +5.45, requires clear, dark clear skies to be observed. 16 Tauri is a blue-white B-type subgiant with an apparent magnitude of +5.45. It is approximately 430 light years from Earth; about the same distance as the Pleiades. The interstellar extinction of this star is fairly small at 0.05 magnitudes. The projected rotational velocity of the equator is 185 km/s. It is over four times the radius of the Sun and has a surface temperature of 12,800 K. USS Celeno (AK-76) was a United States Navy Crater class cargo ship named after the star.
    6.00
    3 votes
    161
    Lambda Aquilae

    Lambda Aquilae

    Lambda Aquilae (λ Aql, λ Aquilae) is a star in the constellation Aquila. It has the traditional name Al Thalimain, which it shares with ι Aquilae. The name is derived from the Arabic الثالمين al-thalīmain "the two ostriches". Lambda Aquilae is more precisely Al Thalimain Prior. It has an apparent visual magnitude of 3.43, which is bright enough to be seen with the naked eye. Parallax measurements place it at a distance of about 125 light-years (38 parsecs) from Earth. In Chinese, 天弁 (Tiān Biàn), meaning Market Officer, refers to an asterism consisting of λ Aquilae, α Scuti, δ Scuti, ε Scuti, β Scuti, η Scuti, 12 Aquilae, 15 Aquilae and 14 Aquilae. Consequently, λ Aquilae itself is known as 天弁七 (Tiān Biàn qī, English: the Seventh Star of Market Officer.) Lambda Aquilae is a main sequence star with a stellar classification of B9Vn, which means that, like the Sun, it is generating energy at its core through the nuclear fusion of hydrogen. It is more massive than the Sun, with about three times its mass, and radiates about 55 times the Sun's luminosity from its outer envelope at a higher effective temperature of 11,780 K. This temperature gives Lambda Aquilae the blue-white hue that is
    6.00
    3 votes
    162
    Pi3 Orionis

    Pi3 Orionis

    Pi Orionis (π Ori, π Orionis) is the Bayer designation for a star in the equatorial constellation of Orion. It has the traditional name of Tabit and the Flamsteed designation 1 Orionis. At an apparent visual magnitude of 3.16, it is readily visible to the naked eye. Pi Orionis is the brightest star in the lion's hide (or shield) that Orion is holding. The distance to this star, as measured using the parallax technique, is 26.32 light-years (8.07 parsecs). Though no extrasolar planets have been observed around Pi Orionis, the star is considered a prime location for planets as small as the Earth. Pi Orionis is a main-sequence star of spectral type F6 V. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Compared to the Sun, it has about 124% of the mass, 132% of the radius, and nearly 3 times the luminosity. This energy is being radiated from the star's outer atmosphere at an effective temperature of 6,516 K, giving it the yellow-white glow of an F-type star. Pi Orionis is most likely single; a nearby star is probably an optical companion. Although a periodicity of 73.26 days has been observed in the star's radial
    6.00
    3 votes
    163
    Comet Donati

    Comet Donati

    Comet Donati, or Donati's Comet, formally designated C/1858 L1 and 1858 VI, is a long-period comet named after the Italian astronomer Giovanni Battista Donati who first observed it on June 2, 1858. After the Great Comet of 1811, it was the most brilliant comet that appeared in the 19th century. It was also the first comet to be photographed. It was nearest the Earth on October 10, 1858. The comet has an orbital inclination of 116.9°. Abraham Lincoln, then a candidate for a seat in the U.S. Senate, sat up on the porch of his hotel in Jonesboro, Illinois to see "Donti's Comet" on September 14, 1858, the night before the third of his historic debates with Stephen Douglas. Donati's Comet appears as a streak and star in the early evening sky of a painting by William Dyce, A Recollection of October 5th, 1858.
    5.00
    4 votes
    164
    Beta Cancri

    Beta Cancri

    Beta Cancri (β Cnc, β Cancri) is the brightest star in the constellation Cancer. It has the traditional name Tarf or Al Tarf (Altarf), certainly a derivation from Arabic الطرف aṭ-ṭarf "the eye" or طرفة aṭ-ṭarfah "the glance (of Leo)". It is approximately 290 light years from Earth. This is an orange K-type giant,about 49 times the radius of the Sun, with an apparent magnitude of +3.50 and absolute magnitude of -1.25 (visual). It has a faint, fourteenth magnitude, red dwarf companion star located 29 arcseconds away. Jim Kaler's Stars: Al Tarf
    5.67
    3 votes
    165
    Beta Comae Berenices

    Beta Comae Berenices

    Beta Comae Berenices (β Comae Berenices, β Com) is a main sequence dwarf star in the northern constellation of Coma Berenices. It is located at a distance of about 29.78 light-years (9.13 parsecs) from Earth. The Greek letter beta (β) usually indicates that the star has the second highest visual magnitude in the constellation. However, with an apparent visual magnitude of 4.3, this star is slightly brighter than α Comae Berenices. It can be seen with the naked eye, but may be too dim to be viewed from a built-up urban area. This star is similar to our own Sun, being only slightly larger and brighter in absolute magnitude. It has a stellar classification of G0 V, compared to G2 V for the Sun. The effective temperature of the outer envelope is 5,936 K, giving it a yellow hue of a G-type star. In terms of age it is younger than the Sun, being about 3 billion years old. Observations of short term variations in the chromatic activity suggest that the star undergoes differential rotation, with a rotation period of about 11–13 days. Its surface has a measured activity cycle of 16.6 years, compared to 11 years on our Sun. It may also have a secondary activity cycle of 9.6 years. At one
    5.67
    3 votes
    166
    Eris

    Eris

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    • Orbited by: Dysnomia
    Eris, formal designation 136199 Eris, is the most massive known dwarf planet in the Solar System and the ninth most massive body known to orbit the Sun directly. It is estimated to be 2326 (±12) km in diameter, and 27% more massive than Pluto, or about 0.27% of the Earth's mass. Eris was discovered in January 2005 by a Palomar Observatory-based team led by Mike Brown, and its identity was verified later that year. It is a trans-Neptunian object (TNO) and a member of a high-eccentricity population known as the scattered disc. It has one known moon, Dysnomia. As of 2011, its distance from the Sun is 96.6 AU, roughly three times that of Pluto. With the exception of some comets, Eris and Dysnomia are currently the most distant known natural objects in the Solar System. Because Eris appeared to be larger than Pluto, its discoverers and NASA initially described it as the Solar System’s tenth planet. This, along with the prospect of other similarly sized objects being discovered in the future, motivated the International Astronomical Union (IAU) to define the term planet for the first time. Under the IAU definition approved on August 24, 2006, Eris is a "dwarf planet", along with objects
    5.67
    3 votes
    167
    Theta Aquilae

    Theta Aquilae

    Theta Aquilae (θ Aql, θ Aquilae) is a binary star in the constellation Aquila. The combined apparent visual magnitude of the pair is 3.26, making it the fourth brightest member of the constellation. In Chinese, it has the traditional name Tseen Foo, which is derived from the Mandarin 天桴 tiānfú meaning "the heavenly raft(er)"; it may also mean drumsticks, with Altair, Beta Aquilae and Gamma Aquilae being the drum. This distance to this star can be determined through the parallax technique, yielding an estimate of roughly 286 light-years (88 parsecs) from Earth. Theta Aquilae is a double-lined spectroscopic binary, which indicates that the individual components have not been viewed through a telescope; instead, what can be viewed is their combined spectrum with the individual absorption line features shifting back and forth over the course of an orbit because of the Doppler effect. Their orbit has a period of 17.1 days with a large orbital eccentricity is 0.60. At the estimated distance of this system, the angular separation of 3.2 milliarcseconds corresponds to a physical separation of only about 0.24–0.28 Astronomical Units. Both stars have a matching stellar classification of
    5.67
    3 votes
    168
    11 Camelopardalis

    11 Camelopardalis

    11 Camelopardalis or BV Camelopardalis is a star system in the constellation Camelopardalis. It forms a double star with 12 Camelopardalis, which is only 3 arcminutes away. 11 Camelopardalis is a blue-white B-type main sequence dwarf with a mean apparent magnitude of +5.22. It is classified as a Gamma Cassiopeiae type variable star and its brightness varies by 0.07 magnitudes with a period of a few hours. It is approximately 671 light years from Earth.
    6.50
    2 votes
    169
    3552 Don Quixote

    3552 Don Quixote

    • Orbits: Sun
    3552 Don Quixote is a small Amor, Mars-crossing, Jupiter-crossing, potentially hazardous asteroid. It has a highly inclined comet-like orbit, and measures about 19 km in diameter. Its rotation period is 7.7 hours. It was discovered by Paul Wild in 1983, and is named after the comic knight who is the eponymous hero of Cervantes' Spanish novel Don Quixote (1605). Don Quixote is suspected to be an extinct comet. Don Quixote is frequently perturbed by Jupiter.
    6.50
    2 votes
    170
    88 Aquarii

    88 Aquarii

    88 Aquarii is the Flamsteed designation for a star in the equatorial constellation of Aquarius. The Bayer designation of this star is c Aquarii. In dark conditions it is visible to the naked eye with an apparent visual magnitude of +3.68. Based upon parallax measurements, this star is at a distance of around 271 light-years (83 parsecs) from Earth. The spectrum of 88 Aquarii matches an evolved giant star with a classification of K1 III. Its measured angular diameter is 3.24 ± 0.20 mas, which, at the estimated distance of Delta Ophiuchi, yields a physical size of about 29 times the radius of the Sun. The cool, orange hued glow of this star comes from the outer atmosphere's effective temperature of 4,430 K.
    6.50
    2 votes
    171
    Mercury

    Mercury

    • Orbits: Sun
    • Orbit Type: Heliocentric orbit
    Mercury is the innermost planet in the Solar System. It is also the smallest, and its orbit is the most eccentric (that is, the least perfectly circular) of the eight planets. It orbits the Sun once in about 88 Earth days, completing three rotations about its axis for every two orbits. The planet is named after the Roman god Mercury, the messenger to the gods. Mercury's surface is heavily cratered and similar in appearance to Earth's Moon, indicating that it has been geologically inactive for billions of years. Due to its near lack of an atmosphere to retain heat, Mercury's surface experiences the steepest temperature gradient of all the planets, ranging from a very cold 100 K at night to a very hot 700 K during the day. Mercury's axis has the smallest tilt of any of the Solar System's planets, meaning that there are no seasons on its surface. Mercury and Venus can each make appearances in Earth's sky both as a morning star and an evening star (because they are closer to the Sun than the Earth), and at times Mercury can technically be regarded as a very bright object when viewed from Earth; however, its proximity in the sky to the Sun makes it more difficult to see than
    6.50
    2 votes
    172
    Mizar

    Mizar

    The Mizar–Alcor stellar sextuple system consists of the quadruple system Mizar and the binary system Alcor. Mizar (Zeta Ursae Majoris, Zeta UMa, ζ Ursae Majoris, ζ UMa) is a quadruple system of two binary stars in the constellation Ursa Major and is the second star from the end of the Big Dipper's handle. Its apparent magnitude is 2.23 and its spectral class is A1V. Mizar's name comes from the Arabic مئزر mīzar, meaning a waistband or girdle. With normal eyesight one can make out a faint companion just to the east, named Alcor or 80 Ursae Majoris. Alcor is of magnitude 3.99 and spectral class A5V. Mizar and Alcor together are sometimes called the "Horse and Rider," and the ability to resolve the two stars with the naked eye is often quoted as a test of eyesight, although even people with quite poor eyesight can see the two stars. Arabic literature says that only those with the sharpest eyesight can see the companion of Mizar. Astronomer Sir Patrick Moore has suggested that this in fact refers to another star which lies visually between Mizar and Alcor. The name the Arabs used for Alcor was سها (suha), meaning either the ‘forgotten’ or ‘neglected’ one. As of 2007, the best estimates
    6.50
    2 votes
    173
    Sigma Scorpii

    Sigma Scorpii

    Sigma Scorpii (σ Sco, σ Scorpii) is a star system in the constellation Scorpius. It has the traditional name Al Niyat, although this name is sometimes also applied to Tau Scorpii, or to the asterism formed by both Sigma and Tau. This system has a combined apparent visual magnitude of +2.88, making it one of the brighter members of the constellation, although greatly outshone by its neighbor Antares. Based upon parallax measurements made during the Hipparcos mission, the distance to Sigma Scorpii is roughly 696 light years (214 parsecs). North et al. (2007) computed a more accurate estimate of 568+75 −59 light years (174+23 −18 parsecs). The brightest component of the system is a double-lined spectroscopic binary, which means that the pair has not been resolved using a telescope. Instead, their orbit is determined by changes in their combined spectrum caused by the Doppler shift. This indicates that the pair complete an orbit every 33.01 days and have an orbital eccentricity of 0.32. The primary component of the spectroscopic binary, σ Scorpii A, is an evolved giant star with a stellar classification of B1 III. It has around 18 times the mass of the Sun and 12 times the Sun's
    6.50
    2 votes
    174
    Xi Persei

    Xi Persei

    Xi Persei (ξ Per) is a star in the constellation Perseus. It has the traditional name Menkib (Menchib, Menkhib, Arabic for "shoulder" [of the Pleiades]). Menkib has an apparent magnitude of +4.042 and is classified as a blue giant (spectral class O7.5III). It is approximately 1800 light years from Earth. Its apparent luminosity is 13,500 times that of the Sun. If we include the ultraviolet light that emanates from Menkib, however, its total (bolometric) luminosity increases to 330,000 times that of the Sun. The star has a mass of some 40 solar masses and a surface temperature of 37,000 kelvins, making it one of the hottest stars that can be seen with the naked eye.
    6.50
    2 votes
    175
    YZ Ceti

    YZ Ceti

    YZ Ceti is a red dwarf star in the constellation Cetus. Although it is relatively close to the Sun at just 12 light years, this star cannot be seen with the naked eye. It is classified as a flare star that undergoes intermittent fluctuations in luminosity. YZ Ceti is only about 8.5% the mass of our Sun, and is normally less than 1/5,000th as luminous. This star is unusually close to Tau Ceti, a star of spectral class G8. The two are only about 1.6 light years apart, a little more than a third of the distance from the Sun to our nearest neighbor, Proxima Centauri.
    6.50
    2 votes
    176
    Comet Shoemaker-Levy 9

    Comet Shoemaker-Levy 9

    Comet Shoemaker–Levy 9 (formally designated D/1993 F2) was a comet that broke apart and collided with Jupiter in July 1994, providing the first direct observation of an extraterrestrial collision of Solar System objects. This generated a large amount of coverage in the popular media, and the comet was closely observed by astronomers worldwide. The collision provided new information about Jupiter and highlighted its role in reducing space debris in the inner Solar System. The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. Shoemaker–Levy 9, at the time captured by and orbiting Jupiter, was located on the night of March 24, 1993, in a photograph taken with the 40 cm (16 in) Schmidt telescope at the Palomar Observatory in California. It was the first comet observed to be orbiting a planet, and had probably been captured by the planet around 20 – 30 years earlier. Calculations showed that its unusual fragmented form was due to a previous closer approach to Jupiter in July 1992. At that time, the orbit of Shoemaker–Levy 9 passed within Jupiter's Roche limit, and Jupiter's tidal forces had acted to pull the comet apart. The comet was later observed as
    4.75
    4 votes
    177
    Charon

    Charon

    • Orbits: Pluto
    Charon is the largest satellite of the dwarf planet Pluto. It was discovered in 1978 at the United States Naval Observatory Flagstaff Station (NOFS). Following the 2005 discovery of two other natural satellites of Pluto (Nix and Hydra), in 2011, a fourth, S/2011 P 1, and on July 11, 2012, a fifth satellite S/2012 P 1, Charon may also be referred to as (134340) Pluto I. The New Horizons mission is scheduled to visit Charon and Pluto in July 2015. Charon was discovered by U.S. Naval Observatory astronomer James Christy, using the 1.55-meter telescope at NOFS, and was formally announced to the world via the International Astronomical Union on July 7, 1978. On June 22, 1978, he had been examining highly magnified images of Pluto on photographic plates taken at the 61-inch Flagstaff telescope two of months prior. Christy noticed that a slight elongation appeared periodically. Later, the bulge was confirmed on plates dating back to April 29, 1965. Subsequent observations of Pluto determined that the bulge was due to a smaller accompanying body. The periodicity of the bulge corresponded to Pluto's rotation period, which was previously known from Pluto's light curve. This indicated a
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    178
    Delta Boötis

    Delta Boötis

    Delta Boötis (δ Boo, δ Boötis) is a double star in the northern constellation Boötes. Based upon parallax measurements, it is located at a distance of approximately 121.8 light-years (37.3 parsecs) from the Earth. This star is sometimes called Princeps, meaning prince or prime in Latin. The origin of this name is unclear, although it usually appears in an astrological context. The It has an apparent visual magnitude of this star is 3.5, making it visible to the naked eye even during a Full Moon. In Chinese, 七公 (Qī Gōng), meaning Seven Excellencies, refers to an asterism consisting of δ Boötis, 42 Herculis, τ Herculis, φ Herculis, χ Herculis, ν Boötis and μ Boötis. Consequently, δ Boötis itself is known as 七公七 (Qī Gōng qī, English: the Seventh Star of Seven Excellencies.) This system consists of a pair of stars located in physical proximity to each other and sharing a similar motion through space, suggesting that they may form a binary star system. Based upon their angular separation and their distance, they have a projected physical separation of 3,800 Astronomical Units (AU). However, their separation along the line of sight from the Earth remains uncertain, so all that can really
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    179
    Eta Arae

    Eta Arae

    Eta Arae (η Ara, η Arae) is the Bayer designation for a single star in the southern constellation of Ara. It is approximately 299 light-years (92 parsecs) from Earth and is visible to the naked eye with an apparent visual magnitude of 3.76. The spectrum of this star matches a stellar classification of K5 III, indicating that, at an estimated age of seven billion years, it has reached the giant star stage of its evolution. With a mass nearly the same as the Sun, it has an outer envelope that has expanded to nearly 56 times the Sun's radius. The star is now spinning so slowly that it takes more than eleven years to complete a single rotation. Eta Arae is radiating energy into space at an effective temperature of 3,886 K, giving it the orange-hued glow of a K-type star. It has a 14th magnitude optical companion, located 25.7 arcseconds away.
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    180
    Zeta Cassiopeiae

    Zeta Cassiopeiae

    Zeta Cassiopeiae (ζ Cas, ζ Cassiopeiae) is a star in the constellation Cassiopeia. It has a blue-white hue and is classified as a B-type subgiant with an apparent magnitude of +3.67. It is approximately 590 light years from Earth. ζ Cas is a member of an unusual group of variable stars known as "Slowing Pulsating B" (SPB) stars. It shows a pulsation frequency of 0.64 per day (or once every 1.56 days) and displays a weak magnetic field with a strength of roughly 3.35 × 10 T, which varies with a period of 5.37 days. This likely matches the rotation rate of the star, which, when combined with the low projected rotational velocity, indicates the star may be seen nearly pole-on. Zeta Cassiopeiae is a candidate magnetic Bp star that shows an overabundance of helium. The star contains a randomly oriented fossil magnetic field, which impacts the outflow of the stellar wind. Collisions between streams from this stellar wind creates a shock front, with cooling particles settling toward a co-rotating disk. In Chinese astronomy, Zeta Cassiopeiae is called 附路, Pinyin: Fùlù, meaning Auxiliary Road, because this star is marking itself and stand alone in Auxiliary Road asterism, Legs (mansion)
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    181
    Zeta Leporis

    Zeta Leporis

    Zeta Leporis (ζ Lep, ζ Leporis) is a star approximately 70.5 light-years (21.6 parsecs) away in the southern constellation of Lepus. It has an apparent visual magnitude of 3.5, which is bright enough to be seen with the naked eye. In 2001, an asteroid belt was confirmed to orbit the star. Zeta Leporis has a stellar classification of A2 IV-V(n), suggesting that it is in a transitional stage between an A-type main sequence star and a subgiant star. The (n) suffix indicates that the absorption lines in the star's spectrum appear nebulous because it is spinning rapidly, causing the lines to broaden because of the Doppler effect. The projected rotational velocity is 245, giving a lower limit on the star's actual equatorial azimuthal velocity. The star has about 1.46 times the mass of the Sun, along with 1.5 times the radius, and 14 times the luminosity. The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, is only 17% of the abundance in the Sun. The star appears to be a very young, probably around 231 million years in age, but the margin of error spans 50–347 million years old. In 1983, based on radiation in the infrared portion of the
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    182
    243 Ida

    243 Ida

    • Orbits: Sun
    • Orbited by: Dactyl
    243 Ida (/ˈaɪdə/ EYE-də) is an asteroid in the Koronis family of the asteroid belt. It was discovered on 29 September 1884 by Johann Palisa and named after a nymph from Greek mythology. Later telescopic observations categorized Ida as an S-type asteroid, the most numerous type in the inner asteroid belt. On 28 August 1993, Ida was visited by the spacecraft Galileo, bound for Jupiter. It was the second asteroid to be visited by a spacecraft and the first found to possess a satellite. Like all main-belt asteroids, Ida's orbit lies between the planets Mars and Jupiter. Its orbital period is 4.84 years, and its rotation period is 4.63 hours. Ida has an average diameter of 31.4 km (19.5 mi). It is irregularly shaped and elongated, and apparently composed of two large objects connected together in a shape reminiscent of a croissant. Its surface is one of the most heavily cratered in the Solar System, featuring a wide variety of crater sizes and ages. Ida's moon, Dactyl, was discovered by mission member Ann Harch in images returned from Galileo. It was named after the Dactyls, creatures which inhabited Mount Ida in Greek mythology. Dactyl, being only 1.4 kilometres (4,600 ft) in diameter,
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    183
    Alpha Camelopardalis

    Alpha Camelopardalis

    Alpha Camelopardalis (Alpha Cam, α Camelopardalis, α Cam) is a star in the constellation Camelopardalis, with an apparent visual magnitude of 4.301. It is the third brightest star in this not very prominent circumpolar constellation, the first and second brightest stars being β Camelopardalis and CS Camelopardalis, respectively.It is the farthest constellational star, with a distance of 6000 light-years from Earth. This star has a stellar classification of O9.5Iae, with the 'Ia' indicating that it is an O-type luminous supergiant and the 'e' showing that there are emission lines in its spectrum. It is a massive star with 43 times the mass of the Sun and 37 times the Sun's radius. The effective temperature of the outer envelope is 30,000 K; much hotter than the Sun's effective temperature of 5,778 K, giving it the characteristic blue hue of an O-type star. It is emitting 620,000 times the luminosity of the Sun and is a weak X-ray emitter. This star shows multiple patterns of variability. It may be a non-radial pulsating variable star, which is causing changes in the spectrum being emitted by the photosphere. The absorption lines in the optical spectrum show radial velocity
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    3 votes
    184
    N Carinae

    N Carinae

    N Carinae (N Car) is a star in the constellation Carina. It is a white A-type bright giant with an apparent magnitude of +4.35 and is approximately 1760 light years from Earth.
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    185
    1221 Amor

    1221 Amor

    • Orbits: Sun
    1221 Amor is the namesake of the Amor asteroids, a group of near-Earth asteroids whose orbits range between those of Earth and Mars. Amors are often Mars-crossers but they are not Earth-crossers. Eugène Joseph Delporte photographed Amor as it approached Earth to within 16 million kilometers (about 40 times the distance from Earth to the moon); this was the first time that an asteroid was seen to approach Earth so closely. A month later, 1862 Apollo was seen to cross Earth's orbit, and the scientific community suddenly realised the potential threat these flying mountains presented. Amor is named after the Roman god of love, better known as Cupid. See also 763 Cupido and 433 Eros, which is named after Cupid's Greek counterpart. Coincidentally, 433 Eros, like 1221 Amor, makes close approaches to Earth. It is a Mars-crosser as well.
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    186
    Beta Scorpii

    Beta Scorpii

    Beta Scorpii (β Sco, β Scorpii) is a multiple star system in the southern zodiac constellation of Scorpius. It has the traditional names Acrab, Akrab or Elacrab, all come from (Arabic: العقرب‎) al-'Aqrab, the Scorpion, for the whole constellation, as well as Graffias, a name it shares with Xi Scorpii. It was known as 房宿四 (the Fourth Star of the Room) in Chinese. Observed through a small telescope, Beta Scorpii appears as a binary star with a separation between the two components of 13.5 arcseconds. This pair, β and β, form the top branches of the hierarchy of orbiting components in this system. β Scorpii, the brighter of the pair, consists of two sub-components, β Sco A and β Sco B, orbiting at an angular separation of 3.9 arcseconds with an orbital period of 610 years. β Sco A is itself a spectroscopic binary with the components β Sco Aa and β Sco Ab separated by 1.42 milliarcseconds and an orbital period of 6.82 days. The second visual component, β Scorpii, has two sub-components, β Sco C and β Sco E, orbiting at an angular separation of 0.1328 arcseconds with an orbital period of 39 years. β Sco E is a spectroscopic binary with the components β Sco Aa and β Sco Ab having an
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    187
    C/1861 J1

    C/1861 J1

    The Great Comet of 1861 formally designated C/1861 J1 and 1861 II, is a long-period comet that was visible to the naked eye for approximately 3 months. It was categorized as a Great Comet, one of eight in the 19th century. It was discovered by John Tebbutt of Windsor, New South Wales, Australia, on May 13, 1861, with an apparent magnitude of +4, a month before perihelion (June 12). It was not visible in the northern hemisphere until June 29, but it arrived before word of the comet's discovery. On June 29, 1861, comet C/1861 J1 passed 11.5 degrees from the Sun. On the following day, June 30, 1861, the comet made its closest approach to the Earth at a distance of 0.1326 AU (19,840,000 km; 12,330,000 mi). During the Earth close approach the comet was estimated to be between magnitude 0 and -2 with a tail of over 90 degrees. As a result of forward scattering C/1861 J1 even cast shadows at night (Schmidt 1863; Marcus 1997). During the night of 1861 June 30-July 1, the famed comet observer J. F. Julius Schmidt watched in awe as the great comet C/1861 J1 cast shadows on the walls of the Athens Observatory. The comet may have interacted with the Earth in an almost unprecedented way. For
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    188
    Epsilon Apodis

    Epsilon Apodis

    Epsilon Apodis (ε Aps, ε Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. It has an apparent visual magnitude of 5.06, which is bright enough to be viewed from dark suburban skies. Based upon parallax measurements, it is at a distance of roughly 640 light-years (200 parsecs) from Earth. Based upon a stellar classification of B3 V, this is a massive, B-type main sequence star that is generating energy through the fusion of hydrogen at its core. Epsilon Apodis has more than six times the mass of the Sun and nearly four times the Sun's radius. It is radiating 1,614 times as much luminosity as the Sun from its outer envelope at an effective temperature of 17,050 K. At this heat, it has a blue-white glow that is a characteristic of B-type stars. It is spinning rapidly, with a projected rotational velocity of 255 km/s giving a lower bound for the azimuthal velocity along the equator. Epsilon Apodis is classified as a Gamma Cassiopeiae type variable star and its brightness varies between magnitudes 4.99 and 5.04. In Chinese caused by adaptation of the European southern hemisphere constellations into the Chinese system, 異雀 (Yì Què), meaning
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    189
    Eta Apodis

    Eta Apodis

    Eta Apodis (η Aps, η Apodis) is a star in the southern circumpolar constellation Apus. Based upon parallax measurements from the Hipparcos mission, it is approximately 138 light-years (42 parsecs) from Earth. With an apparent visual magnitude of +4.9, it can be viewed with the naked eye from the southern hemisphere. This star has about 1.77 times the mass of the Sun and 2.13 times the Sun's radius. It is radiating 15.5 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 7,860 K. Eta Apodis is a young star with an age of about 250 million years. The stellar classification of Eta Apodis shows this to be an Am star, which means the spectrum shows chemically peculiarities. In particular, it is a A2-type star showing an excess of the elements chromium and europium. The spectrum displays magnetically-induced features indicating an estimated surface field strength of roughly 360 G. Based upon observations with the Spitzer Space Telescope, this system is emitting an excess of 24 μm infrared radiation. This may be caused by a debris disk of dust orbiting at a distance of more than 31 astronomical units from the star. In Chinese caused by adaptation of
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    190
    Saturn

    Saturn

    • Orbits: Sun
    • Orbited by: Atlas
    Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Named after the Roman god Saturn, its astronomical symbol (♄) represents the god's sickle. Saturn is a gas giant with an average radius about nine times that of Earth. While only one-eighth the average density of Earth, with its larger volume Saturn is just over 95 times as massive as Earth. Saturn's interior is probably composed of a core of iron, nickel and rock (silicon and oxygen compounds), surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and an outer gaseous layer. The planet exhibits a pale yellow hue due to ammonia crystals in its upper atmosphere. Electrical current within the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is slightly weaker than Earth's and around one-twentieth the strength of Jupiter's. The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 km/h (1,100 mph), faster than on Jupiter, but not as fast as those on Neptune. Saturn has a prominent ring system that
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    191
    15017 Cuppy

    15017 Cuppy

    • Orbits: Sun
    Asteroid 15017 Cuppy, a main-belt object previously known as 1998 SS25, was discovered on September 22, 1998, by Edward L. G. Bowell of the Lowell Observatory Near-Earth-Object Search (LONEOS), Anderson Mesa Station. It was named in September 2003 for Will Cuppy (1884–1949), American humorist and journalist.
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    192
    Delta Aquilae

    Delta Aquilae

    Delta Aquilae (δ Aql, δ Aquilae) is a binary star system in the equatorial constellation of Aquila. The traditional name for this star is Denebokab. It has an apparent visual magnitude of 3.4 and, based upon parallax measurements, is located about 50.6 light-years (15.5 parsecs) from Earth. Delta Aquilae is an astrometric binary where the two components orbit each other with a period of 3.422 years and an eccentricity of about 0.36. This is a type of binary star system where the presence of the secondary component is revealed by its gravitational perturbation of the primary. The individual components have not been resolved with a telescope. The primary component, Delta Aquilae A, is a subgiant star with a stellar classification of F0 IV, where the luminosity class of IV indicates it is in the process of exhausting the supply of hydrogen at its core and evolving into a giant star. The mass of the star is 65% greater than the Sun and it has expanded to more than double the Sun's radius. It is radiating around 7–8 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 7,016 K, giving it the yellow-white hue of an F-type star. Delta Aquilae A is a
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    193
    Gamma Cygni

    Gamma Cygni

    Gamma Cygni (γ Cyg, γ Cygni) is the Bayer designation for a star in the northern constellation Cygnus, forming the intersection of an asterism of five stars called the Northern Cross. It has the traditional name Sadr (also spelled Sadir or Sador), which name comes from the Arabic word صدر şadr, "chest", the same word which gave rise to the star Schedar (Alpha Cassiopeiae). In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Sadr al Dedjadjet, (صدرألدجاجة-şadr aldajaaja), which was translated into Latin as Pectus Gallinǣ, meaning the hen's chest. In Chinese, 天津 (Tiān Jīn), meaning Celestial Ford, refers to an asterism consisting of γ Cygni, δ Cygni, 30 Cygni, α Cygni, ν Cygni, τ Cygni, υ Cygni, ζ Cygni and ε Cygni. Consequently, γ Cygni itself is known as 天津一 (Tiān Jīn yī, English: the First Star of Celestial Ford.). With an apparent visual magnitude of 2.23, this is among the brighter stars visible in the night sky. Parallax measurements give a distance estimate of 1,800 light years (560 parsecs), with a 15% margin of error. The stellar classification of this star is F8 Iab, indicating that it has reached the supergiant stage of its
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    194
    OGLE-2005-BLG-169L

    OGLE-2005-BLG-169L

    OGLE-2005-BLG-169L is a dim and distant magnitude 20 galactic bulge star located about 2,700 parsecs away in the constellation Sagittarius. If it is a main sequence star, then it is most likely a red dwarf with about half of the mass of the Sun. Other possibilities are a white dwarf star, or (less likely) a neutron star or black hole. In 2006, an Uranus-mass extrasolar planet was detected by gravitational microlensing around this star.
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    195
    Pleione

    Pleione

    Pleione (28 Tauri, BU Tauri) is a binary star in the Pleiades star cluster (M45), located roughly 390 light years away in the constellation of Taurus. Pleione was not given a Bayer designation, but did receive a Flamsteed number—hence its designation 28 Tauri. Since the star is located close to Atlas, it's difficult for stargazers to distinguish with the naked eye, even though it's a hot type B star 190 times more luminous than the Sun. Pleione rotates even faster than Achernar on its axis, close to its breakup velocity. The brighter star of the binary pair, component A, is a classical Be star with certain distinguishing traits: periodic phase changes and a complex circumstellar environment composed of two gaseous disks at different angles to each other. Although some research on the system has been performed, stellar characteristics of the orbiting B component are not well known. Pleione is the seventh brightest star in the Pleiades, after Taygeta. With an apparent magnitude of +5.05 in V, the star is rather difficult to make out with the naked eye, especially since its close neighbour Atlas is 3.7 times brighter and located less than 5 arcminutes away. Beginning in October of
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    196
    216 Kleopatra

    216 Kleopatra

    • Orbits: Sun
    • Orbited by: Cleoselene
    216 Kleopatra ( /ˌkliːɵˈpætrə/) is a main-belt asteroid. It was discovered by Johann Palisa on April 10, 1880, from Pula. It is named after Cleopatra, the famous queen of Ancient Egypt. It is notable for its peculiar bilobate shape, which has been compared to a dog's bone. It was recently discovered to be a ternary asteroid, having two small moons. Kleopatra is a relatively large asteroid, measuring 217 × 94 × 81 km. Calculations from its radar albedo and the orbits of its moons show it to be a rubble pile, a loose amalgam of metal, rock, and 30–50% empty space by volume, likely due to a disruptive impact prior to the impact that created its moons. Kleopatra has an unusual shape that has been compared to a dog's bone. This bilobate shape was revealed by adaptive optics on the ESO 3.6 m Telescope at La Silla, run by the European Southern Observatory. By bouncing radar signals off the asteroid, a team of astronomers at the Arecibo radio telescope in Puerto Rico were able to develop a more detailed computer model of its shape, which confirmed the earlier results. In September 2008, Franck Marchis and his collaborators announced that by using the Keck Observatory's adaptive optics
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    197
    65 Cybele

    65 Cybele

    • Orbits: Sun
    65 Cybele is one of the largest asteroids in the Solar System and is located in the outer asteroid belt. It gives its name to the Cybele family of asteroids that orbit outward from the Sun from the 2:1 orbital resonance with Jupiter. Cybele is a C-type asteroid, meaning that it is dark in color and carbonaceous in composition. It was discovered in 1861 by Ernst Tempel and named after Cybele the earth goddess. Cybele was discovered on March 8, 1861, by Ernst Tempel from the Marseilles Observatory. A minor controversy arose from its naming process. Tempel had awarded the honour of naming the asteroid to Carl August von Steinheil in recognition of his achievements in telescope production. Von Steinheil elected to name it "Maximiliana" after the reigning monarch Maximilian II of Bavaria. At the time, asteroids were conventionally given classical names, and a number of astronomers protested this contemporary appellation. The name Cybele was chosen instead, referring to the Phrygian goddess of the earth. The first Cybelian stellar occultation was observed on October 17, 1979 in the Soviet Union. The asteroid appeared to have an irregular shape, with the longest chord being measured as
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    198
    Chi Aquarii

    Chi Aquarii

    Chi Aquarii (χ Aqr, χ Aquarii) is the Bayer designation of a star in the equatorial constellation of Aquarius. The distance to this star, based upon parallax measurements with a 7% margin of error, is roughly 610 light-years (190 parsecs). It is visible to the naked eye with an apparent visual magnitude of +5.06. This is a red giant star with a spectral classification of M3 III. The interferometry-measured angular diameter of this star is 6.70 ± 0.15 mas, which, at its estimated distance, equates to a physical radius of about 137 times the radius of the Sun. It is classified as a semi-regular variable star and its brightness varies by an amplitude of 0.0636 in magnitude. The identified pulsation periods are 32.3, 38.5, and 44.9 days.
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    199
    Electra

    Electra

    Electra, also cataloged as 17 Tauri, is a blue-white giant star in the constellation of Taurus. The star is one of the nine brightest stars in the Pleiades open cluster. The most visible stars in this group are named for the Seven Sisters of Greek mythology. The star has an apparent brightness of 3.72, the third brightest of the stars in the group. Electra belongs to the spectral class B6 IIIe and is approximately 370 light years from the Sun. Electra is one of the four Pleiades stars that is classed as a giant; one that is starting to expand as the internal hydrogen fuel in the core is exhausted. The projected rotational velocity of this star is 181 km/s, making it a fast rotator. This is the velocity component of the star's equatorial rotation along the line of sight to the Earth. The estimated inclination of the star's pole is 46.8° ± 1.6, giving it a true equatorial rotational velocity of 320 ± 18 km/s. The rapid rotation rate of this star flattens the poles and stretch the equator. This makes the surface gravity of the star non-uniform and causes temperature variation. This effect is known as gravity darkening, because it results in a variation of radiation by latitude. The
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    200
    Epsilon Aquarii

    Epsilon Aquarii

    Epsilon Aquarii (ε Aqr, ε Aquarii) is the Bayer designation for a star in the equatorial zodiac constellation of Aquarius. It has an the traditional name Albali and is visible to the naked eye with an apparent visual magnitude of 3.77. The distance to this star can be determined from parallax measurements, yielding an estimated value of around 208 light-years (64 pc) from Earth. Epsilon Aquarii is an A-type main sequence star with a stellar classification of A1 V. This star has an obscure traditional name, Albali, from the Arabic البالع albāli‘ "the swallower". (See also Albulaan.) In the catalogue of stars in the Calendarium of Al Achsasi al Mouakket, this star was designated Nir Saad Bula (نير سعد ألبلع - nayyir sa'd al bulaʽ), which was translated into Latin as Lucida Fortunæ Dissipantis, meaning the brightest of luck of the swallower. This star, along with μ Aqr (Albulaan) and ν Aqr (Albulaan), were al Bulaʽ (البلع), the Swallower. In Chinese, 奎宿 (Nǚ Sù), meaning Girl (asterism) (or Woman), refers to an asterism consisting of ε Aquarii, μ Aquarii, 4 Aquarii, 5 Aquarii and 3 Aquarii. Consequently, ε Aquarii itself is known as 女宿一 (Nǚ Sù yī, English: the First Star of Girl /
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    201
    Gamma Cassiopeiae

    Gamma Cassiopeiae

    Gamma Cassiopeiae (γ Cas, γ Cassiopeiae) is the Bayer designation for a star in the northern circumpolar constellation of Cassiopeia. Although it is a fairly bright star with an apparent visual magnitude of 2.47, it has no traditional Arabic or Latin name. However, in Chinese, it has the name Tsih, derived from the word 策 (cè), meaning "the whip". It is located at the center of the distinctive "W" shape that forms the constellation's asterism. American astronaut Virgil Ivan "Gus" Grissom nicknamed the star Navi after his own middle name spelled backwards. The star was used as an easily identifiable navigational reference point during space missions. Based upon parallax measurements made by the Hipparcos satellite, this star is located at a distance of roughly 550 light-years (170 parsecs) from Earth. This is an eruptive variable star, whose brightness changes irregularly between +2.20 mag and +3.40 mag. It is the prototype of the class of Gamma Cassiopeiae variable stars. The apparent magnitude of this star was +2.2 in 1937, +3.4 in 1940, +2.9 in 1949, +2.7 in 1965 and now it is +2.15. At maximum intensity, γ Cassiopeiae outshines both α Cassiopeiae (magnitude +2.25) and β
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    202
    Kappa Cassiopeiae

    Kappa Cassiopeiae

    Kappa Cassiopeiae (κ Cas, κ Cassiopeiae) is a star in the constellation Cassiopeia. κ Cassiopeiae is a blue-white B-type supergiant with a mean apparent magnitude of +4.17. It is approximately 4100 light years from Earth. It is classified as an Alpha Cygni type variable star and its brightness varies from magnitude +4.22 to +4.30.
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    203
    Sigma Sagittarii

    Sigma Sagittarii

    Sigma Sagittarii (Sigma Sgr, σ Sagittarii, σ Sgr) is the second brightest star in the constellation Sagittarius. Its modern name Nunki is an Assyrian or Babylonian name recovered by archaeologists and made public by R. H. Allen. Nunki has an apparent magnitude of +2.05, making it readily visible to the naked eye. The distance to this star, determined using parallax measurements from the Hipparcos astrometry satellite, yields an estimated value of 228 light-years (70 parsecs) from Earth. Nunki has a spectrum matching a stellar classification of B2.5 V, which indicates this is a B-type main sequence star. The total luminosity of σ Sgr is 3300 times that of the Sun while it has a surface temperature of 18,890 K. X-ray emission has been detected from this star, which has an estimated X-ray luminosity of 1.2 × 10 erg s. Sigma Sgr has a magnitude +9.5 optical companion located 5.2 arcminutes away. Because it is close to the ecliptic, Nunki can be occulted by the Moon and very rarely by planets. The last occultation of Nunki by a planet took place on November 17, 1981, when it was occulted by Venus. Furthermore, Nunki is the brightest star that can be principally occulted by an exterior
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    204
    Moon

    Moon

    • Orbits: Earth
    • Orbit Type: Earth orbit
    The Moon (Latin: luna) is the only natural satellite of the Earth, and the fifth largest satellite in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary, having 27% the diameter and 60% the density of Earth, resulting in ⁄81 its mass. The Moon is the second densest satellite after Io, a satellite of Jupiter. The Moon is in synchronous rotation with Earth, always showing the same face with its near side marked by dark volcanic maria that fill between the bright ancient crustal highlands and the prominent impact craters. It is the brightest object in the sky after the Sun, although its surface is actually very dark, with a reflectance similar to that of coal. Its prominence in the sky and its regular cycle of phases have, since ancient times, made the Moon an important cultural influence on language, calendars, art and mythology. The Moon's gravitational influence produces the ocean tides and the minute lengthening of the day. The Moon's current orbital distance, about thirty times the diameter of the Earth, causes it to appear almost the same size in the sky as the Sun, allowing it to cover the Sun nearly
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    205
    Mu Cassiopeiae

    Mu Cassiopeiae

    Mu Cassiopeiae (μ Cas, μ Cassiopeiae) is a binary star system in the constellation Cassiopeia. This system shares the name Marfak with Theta Cassiopeiae, and the name was from Al Marfik or Al Mirfaq (المرفق), meaning "the elbow". In 1961 the close binary nature of this system was discovered by Nicholas E. Wagman at the Allegheny Observatory. Since then the orbital elements of the two stars have been fairly well established. The two stars are separated by a semimajor axis of 7.61 AUs with distance range of 3.3-11.9 AUs. In 1966, the individual components were first resolved by the American astronomer Peter A. Wehinger using the 84-inch reflector at the Kitt Peak National Observatory, allowing an initial estimate of separate masses. Compared to other nearby stars, this pair are moving at a relatively high velocity of 167 km/s through the Milky Way galaxy. They are low metal, Population II stars that are thought to have formed before the galactic disk first appeared. This star will be in constellation Perseus around 5200 AD.
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    206
    Tau Boötis

    Tau Boötis

    Tau Boötis (τ Boo, τ Boötis) is a yellow-white dwarf approximately 51 light-years away in the constellation of Boötes. The system is also a binary star system, with the secondary star being a red dwarf. As of 1999, an extrasolar planet has been confirmed to be orbiting the primary star. The system is a binary. The primary component is a yellow-white dwarf (spectral type F7 V) and secondary is a dim red dwarf (spectral type M2 V). The system is relatively nearby, distance being about 51 light years. The primary star should be easily visible to the unaided eye under dark skies. The primary star, Tau Boötis A is a yellow-white dwarf. It is 20% more massive than our Sun and thus is somewhat brighter and hotter. It has a radius 1.9 times solar, and is probably about 1300 million years old. Since it is more massive than the Sun, its lifespan is shorter being less than 6000 million years. Tau Bootis is the first star apart from the sun to be observed changing the polarity of its magnetic field. It is also listed as a suspected variable star. However, the star is not variable. Tau Boötis B (with a capital B, as opposed to the planet) is a dim red dwarf orbiting the primary star at a
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    207
    Beta Boötis

    Beta Boötis

    Beta Boötis (β Boo, β Boötis) is the Bayer designation for a star in the northern constellation of Boötes. It has an apparent visual magnitude of 3.5, making it one of the brighter members of the constellation. The traditional name Nakkar or Nekkar for this star is based upon the Arabic name for the constellation. This is a mis-transliteration of the Arabic بقّار baqqār "cattle driver", the Arabic letters b and n differing only in the placement of the dot. In the modern constellation, it marks the head of Boötis the herdsman. Based upon parallax measurements, this star is approximately 225 light-years (69 parsecs) from Earth. At that distance, the magnitude of the star is reduced by 0.06 from extinction caused by intervening gas and dust. Nakkar has more than three times the mass of the Sun and greater than 21 times the Sun's radius. (König et al. (2006) give it 3.4 solar masses, while Tetzlaff et al. (2011) list a higher estimated mass of 5.0 ± 1.5 solar masses and Takeda et al. (2008) show it as 3.24 solar masses.) At the estimated age of 240–251 million years, it has evolved into a giant star with a stellar classification of G8 IIIa. The star is radiating around 170–194 times as
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    208
    Eta Antliae

    Eta Antliae

    Eta Antliae (η Ant, η Antliae) is the Bayer designation for a double star in the southern constellation of Antlia. The brighter component has an apparent visual magnitude of 5.222, making it visible to the naked eye. Parallax measurements of the system yield a distance estimate of 108.6 light-years (33.3 parsecs) from Earth. The main component has a stellar classification of F1 V, which indicates that it is an F-type main sequence star. This star has 55% more mass than the Sun. It shines with 6.6 times the Sun's luminosity at an effective temperature of 7,132 K. This heat gives it the yellow-white glow of an F-type star. It has a faint companion located 31 arcseconds away with an apparent magnitude of +11.3. Most likely this pair form a binary star system.
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    209
    Spica

    Spica

    Spica (α Vir, α Virginis, Alpha Virginis, pronounced /ˈspaɪkə/) is the brightest star in the constellation Virgo, and the 15th brightest star in the nighttime sky. It is 260 light years distant from Earth. A blue giant, it is a variable of the Beta Cephei type. Spica is believed to be the star that provided Hipparchus with the data which enabled him to discover precession of the equinoxes. A temple to Menat (an early Hathor) at Thebes was oriented with reference to Spica when it was constructed in 3200 BC and, over time, precession resulted in a slow but noticeable change in the location of Spica relative to the temple. Nicolaus Copernicus made many observations of Spica with his home-made triquetrum for his researches on precession. As one of the nearest massive binary star systems to the Sun, Spica has been the subject of many observational studies. Spica is a close binary star whose components orbit about each other every four days. They remain sufficiently close together that they can not be resolved as individual stars through a telescope. The changes in the orbital motion of this pair results in a Doppler shift in the absorption lines of their respective spectra, making them
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    210
    51 Andromedae

    51 Andromedae

    51 Andromedae is a 4th magnitude star, the 5th brighest in the constellation Andromeda. It does not have a Bayer designation. It is occasionally called by the proper name Nembus in Bayer's Uranometria (1603) and Bode's star atlas Uranographia (1801). Ptolemy included this star in Andromeda in the Almagest, but it was moved into Perseus by Johann Bayer, who designated it Upsilon Persei (υ Per). Flamsteed moved it back, and the International Astronomical Union made Flamsteed's 51 Andromedae its official designation in 1930. In Chinese, 天大將軍 (Tiān Dà Jiāng Jūn), meaning Heaven's Great General, refers to an asterism consisting of 51 Andromedae, γ Andromedae, φ Persei, 49 Andromedae, χ Andromedae, υ Andromedae, τ Andromedae, 56 Andromedae, β Trianguli, γ Trianguli and δ Trianguli. Consequently, 51 Andromedae itself is known as 天大將軍三 (Tiān Dà Jiāng Jūn sān, English: the Third Star of Heaven's Great General.) 51 Andromedae is an orange K-type giant with an apparent magnitude of +3.59. It is approximately 177 light years from the Earth.
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    211
    Beta Canis Majoris

    Beta Canis Majoris

    Beta Canis Majoris (β CMa, β Canis Majoris) is a star in the southern constellation of Canis Major, the 'greater dog', and is located at a distance of about 500 light-years (150 parsecs) from the Earth. In the modern constellation it lies at the position of the dog's head. It has the traditional name Murzim, Al-Murzim or Mirzam, which is derived from the Arabic (مرزم) for 'The Herald', and probably refers to its position, heralding Sirius in the night sky (i.e., rising before it). In Chinese, 軍市 (Jūn Shì), meaning Market for Soldiers, refers to an asterism consisting of β Canis Majoris, ν Canis Majoris, 15 Canis Majoris, π Canis Majoris, ο Canis Majoris and ξ Canis Majoris. Consequently, β Canis Majoris itself is known as 軍市一 (Jūn Shì yī, English: the First Star of Market for Soldiers). From this Chinese name arose the name Kuen She. The Dunhuang Star Chart noted β Canis Majoris as Yeji "Pheasant Cock", though was located about 10 degrees too far north of its correct position. Murzim is a Beta Cephei variable that varies in apparent magnitude between +1.95 and +2.00 over a six-hour period, a change in brightness that is too small to be discerned with the naked eye. It exhibits this
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    212
    Delta Antliae

    Delta Antliae

    Delta Antliae (δ Ant, δ Antliae) is the Bayer designation for a binary star system in the southern constellation of Antlia. The combined apparent visual magnitude of the system is +5.57, allowing it to be viewed from the suburbs with the naked eye. Judging by the parallax shift of this system, is located at a distance of roughly 480 light-years (150 parsecs) from Earth. The system is reduced in magnitude by 0.03 due to extinction caused by intervening gas and dust. The primary component of the system has a stellar classification of B9.5 V, indicating that it is a B-type main sequence star. The companion is an F-type main sequence star with a classification of F9 Ve, where the 'e' indicates that there are emission lines in the spectrum. The two stars are separated by 11 arcseconds. Delta Antliae A, the brighter member of this system, has an estimated 3.4 times the mass of the Sun. It is radiating around 200 times as much luminosity as the Sun from its outer atmosphere at an effective temperature of 11,117 K. At this heat, it shines with the characteristic blue-white hue of a B-type star.
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    213
    Delta3 Canis Minoris

    Delta3 Canis Minoris

    Delta Canis Minoris (δ CMi, δ Canis Minoris) is a star in the constellation Canis Minor. It is approximately 680 light years from Earth. δ Canis Minoris is a white A-type main sequence dwarf with an apparent magnitude of +5.83.
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    214
    Epsilon Antliae

    Epsilon Antliae

    Epsilon Antliae (ε Ant, ε Antliae) is the Bayer designation for a star in the southern constellation of Antlia. The apparent visual magnitude of this star is +4.51, which means it is visible to the naked eye. From parallax measurements, the distance to this star is known to be around 710 light-years (220 parsecs). Photometry measurements during the Hipparcos mission indicate that this star is undergoing periodic variability by 0.0034 magnitudes over an 11.07941 day cycle. The stellar classification of this star is K3 IIIa, where the luminosity class of III indicates that this is an evolved giant star. It is around 37 times the radius of the Sun.
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    215
    Gamma Leonis

    Gamma Leonis

    Gamma Leonis (γ Leo, γ Leonis) is a binary star system in the constellation Leo. It has the traditional name Algieba or Al Gieba. The name Algieba originates from the Arabic الجبهة Al-Jabhah, meaning the forehead. Despite this meaning, the star actually appears in the mane of Leo. The star's Latin name is Juba. It is known as 軒轅十二 (the Twelfth Star of Xuanyuan) in Chinese. Xuanyuan is the name of Yellow Emperor. Algieba, as a binary system, consists of two stars. The brighter component has an apparent magnitude of +2.28 and is of spectral class K1-IIIbCN-0.5. The giant K star has a surface temperature of 4,470 K, a luminosity 180 times that of Earth's Sun, and a diameter 23 times that of the Sun. The companion star has an apparent magnitude of +3.51 and belongs to the spectral class G7IIICN-I. The giant G star has a temperature of 4,980 K, a luminosity of 50 times that of the Sun, and a diameter 10 times that of the Sun. With angular separation of just over 4", the two stars are at least 170 AU apart (four times the distance between Pluto and the Sun), and have an orbital period of over 500 years. Because the orbital period is so long, only a fraction of the full path has been
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    216
    Mu Boötis

    Mu Boötis

    Mu Boötis (μ Boo, μ Boötis) is a triple star system in the constellation Boötes. It has the traditional name Alkalurops (also Inkalunis, Clava, and Venabulum), and the Flamsteed designation 51 Boötis. Mu Boötis is approximately 121 light-years from Earth. The name Alkalurops is from Greek καλαύροψ kalaurops "shepherd's staff", through the Arabic. It is known as 七公六 (the Sixth Star of the Seven Excellencies) in Chinese. The primary component, μ¹ Boötis, is a yellow-white F-type subgiant with an apparent magnitude of +4.31. Separated from the primary by 108 arcseconds in the sky is the binary star μ² Boötis, which has a combined spectral type of G1V and a combined brightness of +6.51 magnitudes. The components of μ² Boötis have apparent magnitudes of +7.2 and +7.8 and are separated by 2.2 arcseconds. They complete one orbit about their common centre of mass every 260 years.
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    217
    Mu Herculis

    Mu Herculis

    Mu Herculis is a nearby star system about 27.1 light years from Earth in the constellation Hercules. Its main star, Mu Herculis A is fairly similar to the Sun although more highly evolved with a stellar classification of G5 IV. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. Its mass is about 1.1 times that of the Sun, and it is beginning to expand to become a giant. The secondary component consists of a pair of stars that orbit about each other with a period of 43.2 years. Mu Herculis A and the binary pair B-C are separated by 286 AUs. The stars B-C are separated from each other by 11.4 AUs. Their orbit is quite elliptic (e=0.18) and both stars swing each other between 9.4 and 13.5 AUs. In the catalogue of stars in the Calendarium of Al Achsasi Al Mouakket, this star was designated Marfak Al Jathih Al Aisr, which was translated into Latin as Cubitum Sinistrum Ingeniculi, meaning the left elbow of kneeling man. In Chinese, 天市左垣 (Tiān Shì Zuǒ Yuán), meaning Left Wall of Heavenly Market Enclosure, refers to an asterism which is represent eleven old states in China which is marking the left borderline of the
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    218
    Zeta Canis Minoris

    Zeta Canis Minoris

    Zeta Canis Minoris (ζ CMi, ζ Canis Minoris) is a star in the constellation Canis Minor. ζ Canis Minoris is a blue-white B-type bright giant with an apparent magnitude of +5.13. It is approximately 420 light years from Earth.
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    219
    Alpha Caeli

    Alpha Caeli

    Alpha Caeli (α Cae, α Caeli) is a double star system in the constellation Caelum. Alpha Caeli A is an F-type main sequence star with a stellar classification of F2V and an apparent magnitude of +4.44. It has 1.48 times the mass of the Sun and 1.3 times the solar radius. The projected rotational velocity at the stellar equator is 47.8 km/s. It is suspected of being a Delta Scuti variable star. The companion is a spectral class M0.5V red dwarf star with absolute magnitude 9.80. It is a UV Ceti variable star that undergoes random increases in luminosity. This star is currently separated from the primary by an angle of 6.6 arcseconds, which indicates an orbit with a semimajor axis whose expected value is 206 AU. Alpha Caeli is approximately 65.7 light years from Earth and is an estimated 900 million years old. The space velocity components of this system are U = 10, V = 6 and W = -10 km/s. It is orbiting the Milky Way galaxy at an average distance of 8.006 kpc from the core and with an orbital eccentricity of 0.07. This orbit lies close to the galactic plane, and the system travels no more than 0.05 kpc above or below this plane. Alpha Caeli is probably a member of the Ursa Major
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    220
    C/1811 F1

    C/1811 F1

    The Great Comet of 1811, formally designated C/1811 F1, is a comet that was visible to the naked eye for around 260 days, a record it held until the appearance of Comet Hale-Bopp in 1997. In October 1811, at its brightest, it displayed an apparent magnitude of 0, with an easily visible coma. The comet was discovered March 25, 1811 by Honoré Flaugergues at 2.7 AU from the sun in the now-defunct constellation of Argo Navis. After being obscured for several days by moonlight, it was also found by Jean-Louis Pons on April 11, while Franz Xaver, Baron Von Zach was able to confirm Flaugergues' discovery the same night. The first provisional orbit was computed in June by Johann Karl Burckhardt. Based on these calculations, Heinrich Wilhelm Matthäus Olbers made a prediction that the comet would go on to become extremely bright later that year. From May to August, the comet's position made it difficult to spot because of its low altitude and the evening twilight. Both Flaguergues and Olbers were able to recover it in Leo Minor during August, Olbers noting a small but distinct tail, consisting of two rays forming a parabola, when viewing through a comet seeker. By September, in Ursa Major,
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    221
    86 Aquarii

    86 Aquarii

    86 Aquarii is the Flamsteed designation for a binary star system in the equatorial constellation of Aquarius. It is faint but visible to the naked eye with an apparent visual magnitude of +4.47. Based upon parallax measurements, the distance to this star is about 220 light-years (67 parsecs). The two components of this system have an angular separation of 0.25 arcseconds. The brighter component is a giant star with a spectral classification of G8 III and an apparent magnitude of 4.79. The effective temperature of its outer atmosphere is 4,900 K, giving it the yellowish glow of a G-type star. The fainter component is a star of magnitude 6.77.
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    222
    Beta Pegasi

    Beta Pegasi

    Beta Pegasi (β Peg, β Pegasi) is a star in the constellation Pegasus. The apparent visual magnitude of this star averages 2.42, making it the second brightest star in the constellation after Epsilon Pegasi. Its traditional name is Scheat, a name that has also been used for Delta Aquarii. According to Richard H. Allen, this name comes from the Arabic Al Sā'id for 'the upper arm', or from Sa'd. Arabian astronomers named it Mankib al Faras, meaning the "Horse's shoulder". It forms the upper right corner of the Great Square of Pegasus, a prominent rectangular asterism. Based upon parallax measurements, Beta Pegasi is located about 196 light-years (60 parsecs) from the Earth. It is unusual among bright stars in having a relatively cool surface temperature compared to stars like the Sun. This star has a stellar classification of M2.3 II-III, which indicates the spectrum has the characteristics of a star part way between a subgiant and a red giant. It has expanded until it is some 95 times as large, and has a total luminosity of 1500 times that of the Sun. The effective temperature of the star's outer envelope is about 3,700 K, giving the star the characteristic orange-red hue of an
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    223
    Delta1 Canis Minoris

    Delta1 Canis Minoris

    Delta Canis Minoris (δ CMi, δ Canis Minoris) is a star in the constellation Canis Minor. δ Canis Minoris is a yellow-white F-type giant with an apparent magnitude of +5.24. It is approximately 790 light years from Earth.
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    224
    Merope

    Merope

    Merope (23 Tauri) is a star in the constellation Taurus and a member of the Pleiades star cluster. It is approximately 360 light years from Earth. Merope is a blue-white B-type subgiant with a mean apparent magnitude of +4.14. Richard Hinckley Allen described the star as lucid white and violet. It has a luminosity of 630 times that of the Sun and a surface temperature of 14,000 kelvins. Merope's mass is roughly 4.5 solar masses and has a radius more than 4 times as great as the Sun's. It is classified as a Beta Cephei type variable star and its brightness varies by 0.01 magnitudes. Surrounding Merope is the Merope Nebula. Part of the nebula that the Pleiades Cluster is currently passing through, it appears brightest around Merope and is listed in the Index Catalogue as number IC 349.
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    225
    OGLE-2005-BLG-390L

    OGLE-2005-BLG-390L

    OGLE-2005-BLG-390L is a star thought to be a spectral type M - red dwarf star (95% probability, 4% probability it is a white dwarf,
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    226
    Thuban

    Thuban

    Thuban also known by its Bayer designation Alpha Draconis (α Draconis, α Dra) is a star (or star system) in the constellation of Draco. A relatively inconspicuous star in the night sky of the Northern Hemisphere, it is historically significant as having been the north pole star in ancient times. Thuban is an Arabic word for snake ثعبان thuʿbān. Even though Johann Bayer gave Thuban the designation Alpha, its apparent magnitude of 3.65 is 3.7 times fainter than the brightest star in the constellation, Gamma Draconis (Eltanin), whose apparent magnitude is 2.24. Given good viewing conditions, Thuban is relatively easy to spot in the night sky, due to its location in relation to the Big Dipper asterism of Ursa Major. While it is well known that the two outer stars of the 'dipper' point to the modern-day pole star Polaris, it is less well known that the two inner stars, Phecda and Megrez, point to Thuban, just 15 degrees of arc from Megrez. Thuban is not bright enough to be viewed from badly light-polluted areas. Due to the precession of Earth's rotational axis, Thuban was the naked-eye star closest to the north pole from 3942 BC, when it moved farther north than Theta Boötis, until 1793
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    227
    1862 Apollo

    1862 Apollo

    • Orbits: Sun
    • Orbited by: S/2005 (1862) 1
    1862 Apollo ( /əˈpɒloʊ/) is a Q-type asteroid, discovered by Karl Reinmuth in 1932, but lost and not recovered until 1973. It is named after the Greek god Apollo. It is the namesake of the Apollo asteroids, and the first one discovered, although because it was lost for a time its asteroid number (1862) is higher than that of some other Apollo asteroids such as 1566 Icarus. Analysis of the spin of this object provided observational evidence of the YORP effect. It was the first asteroid recognized to cross Earth's orbit. It is also a Venus- and Mars-crosser asteroid. On November 4, 2005, it was announced that an asteroid moon, or satellite of Apollo, had been detected by radar observations from Arecibo Observatory, Puerto Rico, October 29 – November 2, 2005. The standard provisional designation for this satellite is S/2005 (1862) 1. The announcement is contained in the International Astronomical Union Circular (IAUC) 8627 . The satellite is just 80 m across and orbits Apollo closely, in an orbit a mere 3 km in radius .
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    228
    44 Boötis

    44 Boötis

    44 Boötis or i Boötis is a triple star system in the constellation Boötes. It is approximately 41.6 light years from Earth. The primary component, 44 Boötis A, is a yellow-white F-type main sequence dwarf with a mean apparent magnitude of +4.83. The companion component, 44 Boötis B, is a W Ursae Majoris variable spectroscopic binary. The brightness of the binary varies from magnitude +5.8 to +6.40 with a period of 6.43 hours. The components of the eclipsing binary are separated by 0.008 Astronomical Units, roughly 3 times the distance of the Moon from Earth. Recent analysis in timing variations for 44 Bootis B would suggest the presence of a third body orbiting the W Ursae Majoris-type eclipsing binary with likely substellar mass. Its minimum mass is estimated at 48 times that of Jupiter and the orbital separation at 10.73 AUs (a bit farther away than Saturn in the Solar System). So far unconfirmed, such an object seems unstable considering the system's architecture, with 44 Bootis B-C getting as close as 26.6 AUs to 44 Bootis A, unless it is locked in some kind of peculiar configuration and inclination.
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    229
    Alcyone

    Alcyone

    Alcyone (η Tau, η Tauri, Eta Tauri) is a star system in the constellation Taurus. It is the brightest star in the Pleiades open cluster, which is a young cluster, aged at less than 50 million years. Alcyone is approximately 370 light years from Earth. It is named after the mythological figure Alcyone, one of the mythological Pleiades. It is known as 昴宿六 (the Sixth Star of the Hairy Head) in Chinese. The main star, known as Alcyone A, is a blue-white B-type giant similar to many of the other B-type stars in the Pleiades cluster. It has an apparent magnitude of +2.87 (absolute magnitude = −2.39), and a radius almost 10 times that of the Sun. Its temperature is approximately 13,000 K giving it a total luminosity that is 2,400 times solar. The spectral type of B7IIIe indicates that emission lines are present in its spectrum. Like many Be stars, Alcyone A has a high rotational velocity of 215 km/s, which has created a gaseous disk flung into orbit around the star from its equator. Alcyone is an eclipsing binary, and the two components have a separation of 0.031 arcseconds, or about the distance from the Sun to Jupiter. The binary star is orbited by three companions. Alcyone B and
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    230
    Alpha Antliae

    Alpha Antliae

    Alpha Antliae (Alpha Ant, α Antliae, α Ant) is the brightest star in the constellation of Antlia but it has not been given a proper name. It is approximately 370 light-years from the Solar System. It is a K-type giant star that varies in apparent visual magnitude between 4.22 and 4.29. This star has 2.2 times the mass of the Sun and has expanded to 53 times the solar radius. Compared to the Sun, it has only 41% of the abundance of elements other than hydrogen and helium.
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    231
    Alpha Cancri

    Alpha Cancri

    Alpha Cancri (α Cnc, α Cancri) is a star system in the constellation Cancer. It has the traditional name Acubens (Açubens). Acubens is a fourth-magnitude star with an apparent magnitude of 4.20, making it barely visible to the naked eye under good lighting conditions. Nevertheless, it is 23 times more luminous than the Sun. Its stellar classification is A5m. The Hipparcos mission estimated the distance of Acubens to be roughly 53 parsecs from Earth, or approximately 174 light years away. Since it is near the ecliptic, it can be occulted by the Moon and very rarely by planets. The primary component, α Cancri A, is a white A-type main sequence dwarf with an apparent magnitude of +4.26. Its companion, α Cancri B, is an eleventh magnitude star. In the year 1836, its position angle was observed at 325 degrees with a separation from the main star α Cancri A of 11.3 arcseconds. From studying its light curve during occultation, it is thought that α Cancri A may itself be a close binary, consisting of two stars with similar brightness and a separation of 0.1 arcseconds. USS Acubens (AKS-5) was a United States navy ship
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    232
    Alpha Cassiopeiae

    Alpha Cassiopeiae

    Alpha Cassiopeiae (α Cas, α Cassiopeiae ) is a second magnitude star in the constellation Cassiopeia, with the traditional name Schedar, sometimes spelt Shedir. Though listed as the alpha star by Johann Bayer, Schedar's visual brightness closely rivals the beta star in the constellation, Caph. Depending on which passband is used, α Cas may be marginally brighter or dimmer than β Cas. However, recent calculations from the All-Sky catalog indicate that Schedar is the brightest in Cassiopeia, with a visual magnitude of 2.240. With Schedar located farther away from Earth than Caph, at 228 light years versus 54, Schedar is almost 18 times brighter that its rival insofar as intrinsic brightness is concerned. With a declination of 56° 32' North, Schedar is principally visible in the northern hemisphere. The star is yet discernible to most observers across the globe reaching as far south as Perth, Australia, Santiago, Chile and other settlements north ± 33° South latitude, albeit just above the horizon. Schedar is located in line-of-sight of the Milky Way galaxy, so there are other notable celestial objects one can view close to this star—the Pacman Nebula, NGC 436 and NGC 457 being a
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    233
    Atlas

    Atlas

    Atlas is a triple star system in the Pleiades open cluster (M45). It is also known as 27 Tauri. The primary component, Atlas A, is a blue-white B-type giant with an apparent magnitude of +3.62. It is a spectroscopic binary whose components have magnitudes of +4.1 and +5.6. The binary makes one orbit every 1250 days. Atlas also has a dimmer magnitude +6.8 companion, Atlas B, at a separation of 0.4 arcseconds or at least 52 astronomical units away.
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    Beta Arae

    Beta Arae

    Beta Arae (β Ara, β Arae) is the brightest star in the constellation Ara, with an apparent visual magnitude of 2.8. Parallax measurements place it at a distance of roughly 650 light-years (200 parsecs) from Earth. The spectrum of this star matches a stellar classification of K3 Ib-IIa, with the luminosity class notation 'Ib-IIa' indicating that the star lies part way between a higher luminosity bright giant (IIa) and a lower luminosity supergiant (Ib). This represents two of the evolutionary stages that a massive star passes through after it has exhausted the hydrogen at its core. Beta Arae is radiating energy from its outer envelope at an effective temperature of 4,582 K, which causes it to take on the orange hue of a K-type star. This enlarged star appears to be rotating slowly with a projected rotational velocity of about 5 km s. The abundance of elements other than hydrogen and helium, what astronomer term the star's metallicity, is more than three times the abundance in the Sun. Rarely, this star is called by the name Vasat-ül-cemre in Turkish spelling, derived from Arabic word ﻭﺳﻂ (wasath) and ﺟﻤﻩﺮ (khamra), meaning "middle of fire". In Chinese, 杵 (Chǔ), meaning Pestle,
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    235
    Beta Caeli

    Beta Caeli

    Beta Caeli (β Cae, β Caeli) is the bayer designation for a star in the southern constellation of Caelum. It is categorized as an F-type main sequence star with an apparent magnitude of +5.04. Beta Caeli is approximately 90.2 light years from Earth and slightly over six times brighter than the Sun. In the 1994 videogame Alien Legacy, Beta Caeli is the destination of the UNS Calypso. This ship was sent to colonize the Beta Caeli system, under command of the player.
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    Beta Tauri

    Beta Tauri

    Beta Tauri (β Tau, β Tauri) is the second brightest star in the constellation Taurus, with an apparent magnitude of 1.68. Because it is on the boundary of Taurus and Auriga, it also has the redundant Bayer designation Gamma Aurigae (γ Aur), which today is rarely used. The star has the traditional name Elnath—a reference to "the butting" of the bull's horns. Elnath's absolute magnitude is -1.34, similar to another Taurean star, Maia in the Pleiadian star cluster. Like Maia, Elnath is a B class giant with a luminosity 700 times solar. However being approximately 130 light years distant compared to Maia's estimated 360 light years, Elnath ranks as the second brightest star in the constellation. Uniquely positioned along the plane of our Milky Way Galaxy a few degrees west of the galactic anticenter, Elnath heralds a rich collection of nebulae and star clusters. Relative to our Sun, β Tauri is notable for a high abundance of manganese, but little calcium and magnesium. This star has begun to evolve away from the main sequence. This star can be occulted by the moon. Such occultations occur when the moon's ascending node is near the vernal equinox, as is the case in 2007. Most
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    Chi1 Orionis

    Chi1 Orionis

    Chi Orionis (χ Ori, χ Orionis) is a star about 28 light years away. It is in the constellation Orion. χ Ori is a G0V main-sequence star. It has a faint companion with a mass estimated at about 15% of the mass of the Sun, an orbital period of 14.1 years, and an estimated stellar class of M6. The companion orbits an average distance of 6.1 AU from the primary, but has a fairly high orbital eccentricity, ranging from 3.3 AU out to 8.9 AU from the primary. Because of this red dwarf companion, the likelihood of habitable planets in this system is low. χ Ori is a candidate stream star member of the Ursa Major Moving Group, although there is some evidence to the contrary.
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    Cor Caroli

    Cor Caroli

    Cor Caroli (α CVn, α Canum Venaticorum, Alpha Canum Venaticorum, originally known by the more elaborate Cor Caroli Regis Martyris) is the brightest star in the northern constellation Canes Venatici. The name Cor Caroli means Charles' heart, and was named by Sir Charles Scarborough in honour of Charles I, who was executed in the aftermath of the English Civil War, and otherwise associated to Charles II of England, his son, who was restored to the throne after the interregnum following his father's death. In Chinese, 常陳 (Cháng Chén), meaning Imperial Guards, refers to an asterism consisting of α Canum Venaticorum, 10 Canum Venaticorum, β Canum Venaticorum, 6 Canum Venaticorum, 2 Canum Venaticorum, 67 Ursae Majoris. Consequently, α Canum Venaticorum itself is known as 常陳一 (Cháng Chén yī, English: the First Star of Imperial Guards.) From this Chinese name, the name Chang Chen was appeared. Cor Caroli is a binary star with a combined apparent magnitude of 2.81. The two stars are 19.6 arcseconds apart in the sky and are easily resolved in small telescopes. The system lies approximately 110 light years from Earth. The brighter of the two stars is designated α² Canum Venaticorum, the
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    Delta Aquarii

    Delta Aquarii

    Delta Aquarii (δ Aqr, δ Aquarii) is the third-brightest star in the constellation Aquarius. It has the traditional name Skat, which has also been used for Beta Pegasi. The apparent visual magnitude is 3.3, which can be seen with the naked eye. The distance to this star is estimated as 160 light-years (49 parsecs) based upon parallax measurements. The spectrum of Skat matches a stellar classification of A3 V, indicating this is an A-type main sequence star that is generating energy through the nuclear fusion of hydrogen at its core. This star has double the Sun's mass and a radius 2.4 times as large. It is radiating 26 times the luminosity of the Sun from its outer atmosphere at an effective temperature of around 9,000 K. This heat gives it the characteristic white-hued glow of an A-type star. It has a relatively high rate of rotation, with a projected rotational velocity of 81 km s. Delta Aquarii has been closely examined for a companion, but none has been discovered. Nor does it display a strong signal of excess infrared emission that might indicate the presence of circumstellar matter. Delta Aquarii is a probable stream star member of the Ursa Major Moving Group, which has an
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    Epsilon Carinae

    Epsilon Carinae

    Epsilon Carinae (ε Car, ε Carinae) is a star in the southern constellation of Carina. It is also known by the name Avior. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not visible from the northern hemisphere. Epsilon Carinae is a double star located roughly 560–660 light-years (170–200 parsecs) away from the Earth. Measurements during the Hipparcos mission give the pair an angular separation of 0.46 arcseconds with a difference in magnitude of 2.0. At their estimated distance, this angle is equivalent to a physical separation of around 4 Astronomical Units. This pair may form an eclipsing binary system with a period of 785 days (2.15 years), resulting in a magnitude change of 0.12 during each eclipse. The primary component has an apparent visual magnitude of 2.2, which by itself would still make it the third brightest star in the constellation. It is an evolved giant star with a stellar classification of K0 III. However, examination of the ultraviolet flux from this star suggests it may instead be of spectral type K7. The fainter secondary companion has an apparent visual magnitude of 4.1, which, if it were a solitary star, would be bright
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    Gamma Draconis

    Gamma Draconis

    Gamma Draconis (γ Dra, γ Draconis) is the Bayer designation for a star in the northern constellation of Draco. It has the traditional name Etamin or Eltanin and the Flamsteed designation 33 Draconis. Despite its gamma designation, it is actually the brightest star in Draco at magnitude 2.4, outshining Rastaban (Beta Draconis) by nearly half a magnitude. Its proximity to the zenith point directly overhead of London has earned it the name "Zenith Star." As for other places, it is relatively easy to locate in the night sky. If one finds Vega, Eltanin is the red star just north-northwest of it. Eltanin lies around 154.3 light-years (47.3 parsecs) away, as determined by parallax measurements from the Hipparcos astrometry satellite. In 1728, while unsuccessfully attempting to measure the parallax of this star, James Bradley discovered the aberration of light resulting from the movement of the Earth. Bradley's discovery confirmed Copernicus' theory that the Earth revolved around the Sun. Gamma Draconis is an evolved giant star with a stellar classification of K5 III. Since 1943, the spectrum of this star has served as one of the stable anchor points by which other stars are classified. It
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    Great Daylight Comet of 1910

    Great Daylight Comet of 1910

    The Great January Comet of 1910, formally designated C/1910 A1 and often referred to as the Daylight Comet appeared in January 1910. It was already visible to the naked eye when it was first noticed, and many people independently "discovered" the comet. At its brightest, it outshone the planet Venus, and was possibly the brightest comet of the 20th century. The comet brightened rather suddenly, and was initially visible from the southern hemisphere only. A number of individuals claimed "discovery", but the comet is thought to have been first spotted by diamond miners in the Transvaal before dawn on January 12, 1910, by which time it was already a prominent naked-eye object of apparent magnitude −1. The first astronomer to study the comet properly was Robert T. A. Innes at the Transvaal Observatory in Johannesburg on January 17, after having been alerted two days earlier by the editor of a Johannesburg newspaper. The comet reached perihelion on January 17 and was at that time visible in daylight with the unaided eye; following perihelion, it declined in brightness but became a spectacular sight from the northern hemisphere in the evening twilight, its noticeably curved tail reaching
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    Iota Antliae

    Iota Antliae

    Iota Antliae (ι Ant, ι Antliae) is the Bayer designation for a star in the southern constellation of Antlia. It has an apparent visual magnitude of +4.60, making it a faint naked eye star. From parallax measurements, the distance to this star can be estimated as 190 light-years (58 parsecs). The spectrum of Iota Antliae matches a stellar classification of K1 III, indicating that this is an evolved star that is now in its giant phase. It is a core helium fusing star that is classified as a member of the red clump evolutionary branch.
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    OTS 44

    OTS 44

    OTS 44 is a sub-stellar object known as a brown dwarf, located about 550 light-years (170 pc) away in constellation Chamaeleon. It is among the smallest known brown dwarfs, with about 15 times the mass of Jupiter, or about 1.5% that of the Sun. Its radius is about 23% of the Sun's. This brown dwarf is located in the star-forming region Chamaeleon I. Based upon infrared observations with the Spitzer Space Telescope, OTS 44 emits an excess of infrared radiation for an object of its type, suggesting it has a circumstellar disk of dust and particles of stone and ice. This disk has an inner radius roughly three times the radius of OTS 44 and is accreting matter at the rate of about 10 the mass of the Sun per year. It could eventually develop into a planetary system.
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    Phobos

    Phobos

    • Orbits: Mars
    Phobos ( /ˈfoʊbəs/ FOH-bəs; Greek: Φόβος; systematic designation: Mars I) is the larger and closer of the two natural satellites of Mars. With a mean radius of 11.1 km (6.9 mi), Phobos is 7.24 times as massive as the second moon Deimos. It is named after the Greek god Phobos (which means "fear"), a son of Ares (Mars). Both moons were discovered in 1877. A small, irregularly shaped object, Phobos orbits about 9,400 km (5,800 mi) from the center of Mars, or about 6,000 km (3,700 mi) from the Martian surface, closer to its primary than any other known planetary moon. Phobos is one of the least reflective bodies in the Solar System, and features a large impact crater, Stickney crater. It orbits so close to the planet that it moves around Mars faster than Mars rotates. As a result, from the surface of Mars it appears to rise in the west, move across the sky in 4 h 15 min or less, and set in the east twice in each Martian day. Due to its short orbital period and tidal interactions, Phobos's orbital radius is decreasing and it will eventually either impact the surface of Mars or break up into a planetary ring. Phobos was discovered by astronomer Asaph Hall on August 18, 1877, at the
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    RX J1856.5-3754

    RX J1856.5-3754

    RX J1856.5-3754 (also called RX J185635-3754, RX J185635-375, and various other designations) is a nearby neutron star in Corona Australis. It is believed to have been created by a supernova explosion of its companion star about one million years ago and is moving 108 km/s across the sky. It was discovered in 1992, and observations in 1996 appeared to confirm that it was a neutron star, the closest neutron star to Earth yet discovered. It was originally thought to be about 150–200 light-years away, but further observations using the Chandra X-ray Observatory in 2002 appear to show that its distance is greater—about 400 light-years. It was once proposed that RX J1856.5-3754 was too small to be a neutron star and may therefore in fact be a quark star (see also 3C58). However, this theory is not currently considered to have much supporting evidence. By combining Chandra X-ray Observatory and Hubble Space Telescope data, astronomers previously found that RX J1856 radiates like a solid body with a temperature of 700,000 degrees Celsius and has a diameter of about 4—8 km. This estimated size was too small to reconcile with the standard models of neutron stars, therefore it was suggested
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    Sigma Arietis

    Sigma Arietis

    Sigma Arietis (σ Ari, σ Arietis) is the Bayer designation for a star in the northern constellation of Aries. It has an apparent visual magnitude of +5.52, which is bright enough for the star to be seen with the naked eye from dark suburban skies. Based upon an annual measured parallax shift of 6.60 ± 0.32 mas, it is approximately 494 light-years (151 parsecs) distant from the Earth. Sigma Arietis is a B-type main sequence star with a stellar classification of B7 V. This is a large star with three times the radius of the Sun and 3.8 times the Sun's mass. It shines around 301 times as brightly as the Sun, with this energy being radiated into space from its outer atmosphere at a scorching hot effective temperature of 13,121 K. It is this heat that gives the star the blue-white hue of a B-type star. Sigma Arietis is spinning at a rapid clip, with a projected rotational velocity of 165 km/s. It is a probable member of the Cas-Tau OB association of stars that share a common motion through space.
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    Sun

    Sun

    • Orbits: Galactic Center
    • Orbit Type: Galactocentric orbit
    • Orbited by: Mercury
    The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields. It has a diameter of about 1,392,684 km, about 109 times that of Earth, and its mass (about 2×10 kilograms, 330,000 times that of Earth) accounts for about 99.86% of the total mass of the Solar System. Chemically, about three quarters of the Sun's mass consists of hydrogen, while the rest is mostly helium. The remainder (1.69%, which nonetheless equals 5,628 times the mass of Earth) consists of heavier elements, including oxygen, carbon, neon and iron, among others. The Sun formed about 4.6 billion years ago from the gravitational collapse of a region within a large molecular cloud. Most of the matter gathered in the center, while the rest flattened into an orbiting disk that would become the Solar System. The central mass became increasingly hot and dense, eventually initiating thermonuclear fusion in its core. It is thought that almost all other stars form by this process. The Sun's stellar classification, based on spectral class, is G2V, and is informally designated as a yellow dwarf, because its visible radiation is most intense in
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    Tau Scorpii

    Tau Scorpii

    Tau Scorpii is a star in the southern zodiac constellation of Scorpius. It has the traditional name Alniyat or Al Niyat, which it shares with σ Scorpii. The name derives from the Arabic النياط an-niyāţ meaning "the arteries". The apparent visual magnitude of Tau Scorpii is +2.8, while parallax measurements yield a distance estimate of roughly 470 light-years (150 parsecs) from Earth. Compared to the Sun, Tau Scorpii is a massive OB star with 15 times the Sun's mass and more than six times the radius of the Sun. It is radiating about 18,000 times the Sun's luminosity from its outer envelope at an effective temperature of 31,440 K. This gives it the blue-white hue characteristic of B-type stars. As yet there is no evidence of a companion in orbit around τ Sco. It is a magnetic star whose surface magnetic field was mapped by means of Zeeman–Doppler imaging. Tau Scorpii is rotating relatively slowly with a period of 41 days. The spectrum of this star shows triply-ionized oxygen (O IV) that is being generated by X-rays and the Auger ionization effect. Observations with the ROSAT space telescope showed it has a higher energy (harder) X-ray spectrum than is usual for B0 V stars. Over the
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    Xi Arietis

    Xi Arietis

    Xi Arietis (ξ Ari, ξ Arietis) is the Bayer designation for a star in the northern constellation of Aries. It has an apparent visual magnitude of 5.46, and so is dimly visible to the naked eye. Based upon an annual parallax shift of 3.74 ± 0.29 mas, it is 872 ± 68 light-years (267 ± 21 parsecs) distant from the Earth. The spectrum of this star matches a stellar classification of B7 IV, indicating that it is a subgiant star that has exhausted the supply of hydrogen at its core and is in the process of evolving into a giant star. Xi Arietis was once a designation for Psi Ceti (ψ Cet, ψ Ceti).
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