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Best Astronomical Discovery of All Time

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    1
    9971 Ishihara

    9971 Ishihara

    • Discoverer: Kazuro Watanabe
    • Discovery Site: Kitami Observatory
    9971 Ishihara is a main belt asteroid. It orbits the Sun once every 3.22 years. Discovered on April 16, 1993 by K. Endate and K. Watanabe it was given the provisional designation 1993 HS. It was later renamed Ishihara after Takahiro Ishihara, a former president of the Hiroshima Astronomical Society.
    8.33
    6 votes
    2
    (52760) 1998 ML14

    (52760) 1998 ML14

    (52760) 1998 ML14 (also written (52760) 1998 ML14) is an as yet unnamed near-Earth and Mars-crosser asteroid. It was discovered by LINEAR in 1998. It is approximately 1.5 km in diameter. Shortly after its discovery, 1998 ML14 was imaged by radar at Goldstone and Arecibo. The study showed that the asteroid has a rotation period of 15 hours, and a shape that is roughly spherical, with some steep protrusions and large craters.
    7.83
    6 votes
    3
    9956 Castellaz

    9956 Castellaz

    • Discoverer: Freimut Börngen
    • Discovery Site: Karl Schwarzschild Observatory
    9956 Castellaz is a main belt asteroid. It orbits the Sun once every 3.29 years. Discovered on October 5, 1991 by L. D. Schmadel and F. Borngen it was given the provisional designation "1991 TX4". It was later renamed "Castellaz" after German physicist Peter Castellaz.
    7.67
    6 votes
    4
    HD 69830 d

    HD 69830 d

    • Discovery Organization: High Accuracy Radial Velocity Planet Searcher
    HD 69830 d is an extrasolar planet orbiting the orange dwarf star HD 69830 every 197 days. It is the outermost known planet in its planetary system and possibly lies within its habitable zone. Planet HD 69830 d was discovered in 2006. The planet's orbit has a low eccentricity, like most of the planets in our solar system. The semimajor axis of the orbit is only 0.63 AU, similar to that of Venus. However, HD 69830 is a less massive and energetic star than the Sun, thereby putting the planet within its habitable zone. It is 17 times the mass of the Earth, and 42 light years away from the solar system, and has a close to circular orbit. Given the planet's Neptune-type mass, it is likely that HD 69830 d is a gas giant with no solid surface. Since the planet has only been detected indirectly through its gravitational effects on the star, properties such as its radius and composition are unknown. In the Bestiarum included with the special editions of Halo 3, HD 69830 d is described as the home star of the Jackals, specifically stating that they come from a hypothetical moon of the third planet at the inner edge of the asteroid belt. It is mentioned as a potentially habitable planet on
    7.67
    6 votes
    5
    467 Laura

    467 Laura

    • Discoverer: Max Wolf
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    467 Laura (1901 FY) is Main-belt asteroid discovered on January 9, 1901 by Max Wolf at Heidelberg.
    8.80
    5 votes
    6
    Dysnomia

    Dysnomia

    • Discoverer: Michael E. Brown
    • Discovery Site: W. M. Keck Observatory
    Dysnomia, officially (136199) Eris I Dysnomia (Greek: Δυσνομία), is the only known moon of the dwarf planet Eris (the most-massive known dwarf planet in the Solar System). It was discovered in 2005 by Mike Brown and the laser guide star adaptive optics team at the W. M. Keck Observatory, and carried the provisional designation of S/2005 (2003 UB313) 1 until officially named Dysnomia (from the Ancient Greek word Δυσνομία meaning "lawlessness") after the daughter of the Greek goddess Eris. During 2005, the adaptive optics team at the Keck telescopes in Hawaii carried out observations of the four brightest Kuiper belt objects (Pluto, Makemake, Haumea, and Eris), using the newly commissioned laser guide star adaptive optics system. Observations taken on 10 September revealed a moon in orbit around Eris, provisionally designated S/2005 (2003 UB313) 1. In keeping with the Xena nickname that was already in use for Eris, the moon was nicknamed "Gabrielle" by its discoverers, after Xena's sidekick. Dysnomia was found 4.43 magnitudes fainter than Eris, and its diameter is estimated to be between 350 and 490 km, though Mike Brown claims that it is 500 times fainter and between 100 and 250 km
    8.80
    5 votes
    7
    9995 Alouette

    9995 Alouette

    • Discoverer: Tom Gehrels
    • Discovery Site: Palomar Observatory
    9995 Alouette is an S-type main belt asteroid. It orbits the Sun once every 3.69 years. Discovered on September 24, 1960 by C. J. van Houten and I. van Houten-Groeneveld on archived photographic plates made by T. Gehrels, it was given the provisional designation 4805 P-L. It was later renamed Alouette in honour of Alouette-1, the first Canadian satellite.
    7.50
    6 votes
    8
    944 Hidalgo

    944 Hidalgo

    • Discoverer: Walter Baade
    • Discovery Site: Hamburg-Bergedorf Observatory
    944 Hidalgo ( /hɨˈdælɡoʊ/ hi-DAL-goh) is a small Solar System body with a semi-major axis beyond Jupiter's and an orbital period of 13.77 years. This makes it a centaur, but it was discovered in 1920 and has hence traditionally been considered an asteroid. 944 Hidalgo is a centaur because it has a semi-major axis between Jupiter's and Neptune's. Despite this, the Minor Planet Center (MPC) does not list it as a centaur. Hidalgo has traditionally been considered an asteroid because it was discovered long before the identification of centaurs as a distinct class. With a high eccentricity of 0.66, its perihelion of 1.95 AU takes it to the inner edge of the asteroid belt, while its aphelion of 9.54 AU takes it right out to Saturn's orbit, a characteristic normally associated with Saturn's family of comets. Some astronomers therefore suspect that it was once a comet. Strictly speaking, Hidalgo is a Saturn-grazer rather than a Saturn-crosser as its aphelion does not clear Saturn's. Hidalgo's severe orbital inclination of 43° is suspected to be the result of a close encounter with Jupiter. Even as recently as 1922, Hidalgo passed within 0.89AU of the powerful influence of Jupiter. Its
    7.33
    6 votes
    9
    Horsehead Nebula

    Horsehead Nebula

    • Discoverer: Williamina Fleming
    • Discovery Organization: Harvard College Observatory
    The Horsehead Nebula (also known as Barnard 33 in emission nebula IC 434) is a dark nebula in the constellation Orion. The nebula is located just to the south of the star Alnitak, which is farthest east on Orion's Belt, and is part of the much larger Orion Molecular Cloud Complex. The nebula was first recorded in 1888 by Williamina Fleming on photographic plate B2312 taken at the Harvard College Observatory. The Horsehead Nebula is approximately 1500 light years from Earth. It is one of the most identifiable nebulae because of the shape of its swirling cloud of dark dust and gases, which is similar to that of a horse's head when viewed from Earth. The red or pinkish glow originates from hydrogen gas predominantly behind the nebula, ionized by the nearby bright star Sigma Orionis. The darkness of the Horsehead is caused mostly by thick dust, although the lower part of the Horsehead's neck casts a shadow to the left. Streams of gas leaving the nebula are funneled by a strong magnetic field. Bright spots in the Horsehead Nebula's base are young stars just in the process of forming. The nebula exhibits a noticeable change in the density of the stars which indicates that a red ribbon of
    7.17
    6 votes
    10
    9963 Sandage

    9963 Sandage

    • Discoverer: Eleanor F. Helin
    • Discovery Site: Palomar Observatory
    9963 Sandage is a main belt asteroid. It orbits the Sun once every 3.58 years. Discovered on January 9, 1992 by E. F. Helin, it was given the provisional designation "1992 AN". It was later renamed "Sandage" after Allan Sandage, an American astronomer.
    7.00
    6 votes
    11
    Stephan's Quintet

    Stephan's Quintet

    • Discoverer: Édouard Jean-Marie Stephan
    Stephan's Quintet in the constellation Pegasus is a visual grouping of five galaxies of which four form the first compact galaxy group ever discovered. The group was discovered by Édouard Stephan in 1877 at Marseilles Observatory. The group is the most studied of all the compact galaxy groups. The brightest member of the visual grouping is NGC 7320 that is shown to have extensive H II regions, identified as red blobs, where active star formation is occurring. These galaxies are of interest because of their violent collisions. Four of the five galaxies in Stephan's Quintet form a physical association, Hickson Compact Group 92, and are involved in a cosmic dance that most likely will end with the galaxies merging. Radio observations in the early 1970s revealed a mysterious filament of emission which lies in inter-galactic space between the galaxies in the group. This same region is also detected in the faint glow of ionized atomic hydrogen seen in the visible part of the spectrum as the magnificent green arc in the picture to the right. Two space telescopes have recently provided new insight into the nature of the strange filament, which is now believed to be a giant intergalactic
    6.83
    6 votes
    12
    Upsilon Andromedae b

    Upsilon Andromedae b

    • Discoverer: Geoffrey Marcy
    Upsilon Andromedae b, occasionally referred to as Upsilon Andromedae Ab (to distinguish it from the red dwarf star Upsilon Andromedae B), is an extrasolar planet approximately 44 light-years away from Earth in the constellation of Andromeda (the Chained Maiden). The planet was discovered orbiting the Solar twin star, Upsilon Andromedae, approximately every five days. Discovered in June 1996 by Geoffrey Marcy and R. Paul Butler, it was one of the first hot Jupiters to be discovered. Upsilon Andromedae b is the innermost known planet in its planetary system. Like the majority of known extrasolar planets, Upsilon Andromedae b was detected by the variations in its star's radial velocity caused by the planet's gravity. The variations were detected by making sensitive measurements of the Doppler shift of Upsilon Andromedae's spectrum. The planet was announced in January 1997, together with 55 Cancri b and the planet orbiting Tau Boötis. Like 51 Pegasi b, the first extrasolar planet discovered around a normal star, Upsilon Andromedae b orbits very close to its star, closer than Mercury does to our Sun. The planet takes 4.617 days to complete an orbit, with a semimajor axis of 0.0595 AU. A
    7.80
    5 votes
    13
    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
    6.67
    6 votes
    14
    3753 Cruithne

    3753 Cruithne

    • Discoverer: Duncan Waldron
    • Discovery Site: Siding Spring Observatory
    3753 Cruithne ( /ˈkrɪnjə/, from Old Irish [ˈkrɪθnɛ]; Modern [ˈkrɪhnʲə] or [ˈkrɪnʲə]) is an asteroid in orbit around the Sun in 1:1 orbital resonance with the Earth. It is a minor planet that orbits the Sun in a horseshoe orbit relative to Earth. It has been incorrectly called "Earth's second moon", but it is a quasi-satellite, not a moon. Cruithne does not orbit Earth, and at times it is on the other side of the Sun. Its orbit takes it inwards towards the orbit of Mercury, and outside the orbit of Mars. Cruithne orbits the Sun in about 1 year, but it takes 770 years for the series to complete a horseshoe-shaped movement, with the Earth in the gap of the horseshoe. The name Cruithne is from Old Irish, the Celtic term for the Picts, as well as the name of a people of eastern Ulster. Cruithne was discovered on October 10, 1986, by Duncan Waldron on a photographic plate taken with the UK Schmidt Telescope at Siding Spring Observatory, Coonabarabran, Australia. The 1983 apparition (1983 UH) is credited to Giovanni de Sanctis and Richard M. West of the European Southern Observatory in Chile. It was not until 1997 that its unusual orbit was determined by Paul Wiegert and Kimmo Innanen,
    7.60
    5 votes
    15
    8710 Hawley

    8710 Hawley

    • Discoverer: Charles P. de Saint-Aignan
    • Discovery Site: Palomar Observatory
    8710 Hawley is a Main belt asteroid discovered by Charles de Saint-Aignan at Lowell Observatory, examining films taken at Palomar. Named in honor of the discoverer's friend and mentor, Walter N. Hawley, a physics and astronomy teacher at Saint Paul's School in Concord, New Hampshire. He is also the director of the Saint Paul's Astronomy Center, an observatory of unequaled quality at the high-school level. Hawley has observed the night sky with his students since 1972, acquainting them with such wonders as the Aurora Borealis and Messier Objects, as well as lesser wonders, such as Murphy's Law---and frostbite. †. This orbital diagram is courtesy of the JPL Small-Body Database Browser
    7.60
    5 votes
    16
    Gamma Cephei Ab

    Gamma Cephei Ab

    Gamma Cephei Ab is an extrasolar planet approximately 45 light-years away in the constellation of Cepheus (the King). The planet was confirmed to be in orbit around Gamma Cephei in 2002, but was first suspected to exist around 1988 (making this planet arguably the first true extrasolar planet discovered). The first indications of Gamma Cephei Ab were reported in July 1988. The planet was tentatively identified by a Canadian team of astronomers led by Bruce Campbell, Gordon Walker, and Stephenson Yang, while its existence was also announced by Anthony Lawton and P. Wright in 1989. Though not confirmed, this would have been the first true extrasolar planet, and it was hypothesized based on the same radial velocity technique later used successfully by others. However, the claim was retracted in 1992 due to the quality of the data not being good enough to make a solid discovery. On September 24, 2002, Gamma Cephei Ab was finally confirmed. The team of astronomers (including William D. Cochran, Artie P. Hatzes, et al.) at the Planetary Systems and their Formation Workshop announced the preliminary confirmation of a long-suspected planet Gamma Cephei Ab with a minimum mass of 1.59 MJ
    7.60
    5 votes
    17
    2005 CB79

    2005 CB79

    • Discoverer: Chad Trujillo
    2005 CB79 is a trans-Neptunian object that is a member of the Haumea family. As a member of the Haumea family, 2005 CB79 is suspected of being an icy mantle collisional fragment from dwarf planet Haumea. With an absolute magnitude (H) of 4.7, and a Haumea-family albedo of 0.7, this object would have a diameter of 158 km. Observations by Mike Brown in 2012 using the W. M. Keck Observatory suggest that 2005 CB79 does not have a companion.
    6.50
    6 votes
    18
    6489 Golevka

    6489 Golevka

    • Discoverer: Eleanor F. Helin
    • Discovery Site: Palomar Observatory
    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
    10.00
    3 votes
    19
    (9979) 1994 VT

    (9979) 1994 VT

    • Discoverer: Takao Kobayashi
    • Discovery Site: Oizumi Observatory
    (9979) 1994 VT is a main belt asteroid. It orbits the Sun once every 3.73 years. Discovered on November 3, 1994 by T. Kobayashi, it was given the provisional designation 1994 VT.
    7.40
    5 votes
    20
    10000 Myriostos

    10000 Myriostos

    • Discoverer: Albert George Wilson
    • Discovery Site: Palomar Observatory
    10000 Myriostos is a main-belt asteroid discovered by A. G. Wilson on September 30, 1951 at the Palomar Observatory on Palomar Mountain, California. Given the provisional designation 1951 SY, it was renamed "(10000) Myriostos" (Greek for "ten thousandth") to honor all astronomers who helped discover ten thousand such bodies. This occurred after some debate as to whether Pluto should have been reclassified as a minor planet and given the number 10000, with strong resistance coming from the American Astronomical Society's Division for Planetary Sciences.
    7.40
    5 votes
    21
    243 Ida

    243 Ida

    • Discoverer: Johann Palisa
    • Discovery Site: Vienna Observatory
    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,
    7.40
    5 votes
    22
    142 Polana

    142 Polana

    • Discoverer: Johann Palisa
    • Discovery Site: Pola Observatory
    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
    8.25
    4 votes
    23
    6 Hebe

    6 Hebe

    • Discoverer: Karl Ludwig Hencke
    6 Hebe ( /ˈhiːbiː/ HEE-bee) is a large main-belt asteroid, containing around half a percent of the mass of the belt. Its apparently high bulk density (greater than that of the Earth's Moon or even Mars), however, means that by volume it does not rank among the top twenty asteroids. This high bulk density suggests an extremely solid body that has not been impacted by collisions, which is not typical of asteroids of its size – they tend to be loosely bound rubble piles. In brightness, Hebe is the fifth brightest object in the asteroid belt after Vesta, Ceres, Iris and Pallas. It has a mean opposition magnitude of +8.3, about equal to the mean brightness of Titan and can reach +7.5 at an opposition near perihelion. Hebe is probably the parent body of the H chondrite meteorites, which account for a remarkable 40% of all meteorites striking the Earth. Hebe was the sixth asteroid to be discovered, on July 1, 1847 by Karl Ludwig Hencke. It was the second and final asteroid discovery by Hencke, who had previously found 5 Astraea. The name Hebe, goddess of youth, was proposed by Carl Friedrich Gauss. 6 Hebe is the probable parent body of the H chondrite meteorites and the IIE iron
    8.25
    4 votes
    24
    Dactyl

    Dactyl

    (243) Ida I Dactyl (pronounced /ˈdæktɨl/ dak'-tl) is a tiny asteroid moon (1.4 km in diameter) that orbits asteroid 243 Ida. It was imaged by the Galileo spacecraft on August 28, 1993; the Galileo mission member Ann Harch, while examining the delayed image downloads, discovered it on February 17, 1994. It was provisionally designated S/1993 (243) 1. The satellite was named after the mythical creatures called dactyls who lived on the Mount Ida according to the Greek mythology. Dactyl orbits Ida with a period of 1.54 days at an average distance of 108 km, with an inclination of 9° to Ida's equator. The orbit is not very accurately known because Galileo coincidentally passed very nearly in its plane while taking the images. The origins of Dactyl are unclear, but two main hypotheses exist. The first is that Dactyl and Ida formed at the same time, and the second is that Dactyl was knocked loose by a later impact. Both hypotheses have problems and cannot explain the situation satisfactorily. Dactyl was the first asteroid moon discovered. The discovery settled the long debate over the existence of asteroid moons.
    8.25
    4 votes
    25
    Eris

    Eris

    • Discoverer: Michael E. Brown
    • Discovery Site: Palomar Observatory
    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
    6.17
    6 votes
    26
    Gliese 581 b

    Gliese 581 b

    • Discoverer: Michel Mayor
    Gliese 581 b or Gl 581 b is an extrasolar planet orbiting the star Gliese 581. It is the first planet of six discovered in the system so far, and the second in order from the star. The planet was discovered by a team of French and Swiss astronomers, who announced their findings on November 30, 2005 as a discovery of one of the smallest extrasolar planets ever found, with one conclusion being that planets may be more common around the smallest stars. It was the fifth planet found around a red dwarf star (after Gliese 876's planets and Gliese 436 b). The planet was discovered using the HARPS instrument, with which they found the host star to have a wobble that implied the existence of the planet. The astronomers published their results in Astronomy and Astrophysics Letters. Gliese 581 b is at minimum about 16 times the Earth's mass, similar to Neptune's mass. It does not transit its star, implying that its inclination is less than 88.1 degrees. Dynamical simulations of the Gliese 581 system assuming that the orbits of the four planets are coplanar show that the system becomes unstable if its component masses exceed 1.6 – 2 times their minimum masses. This is primarily due to the
    6.17
    6 votes
    27
    5222 Ioffe

    5222 Ioffe

    • Discoverer: Nikolai Stepanovich Chernykh
    • Discovery Site: Crimean Astrophysical Observatory
    5222 Ioffe (1980 TL13) is a main-belt asteroid discovered on October 11, 1980 by Chernykh, N. S. at Nauchnyj. It is the largest of the Palladian asteroids apart from Pallas itself.
    7.00
    5 votes
    28
    9999 Wiles

    9999 Wiles

    • Discoverer: Tom Gehrels
    • Discovery Site: Palomar Observatory
    9999 Wiles is a C-type main belt asteroid. It orbits the Sun every 4.8 years. It was discovered by C. J. van Houten, I. van Houten-Groeneveld and T. Gehrels on September 29, 1973. Given the provisional designation 4196 T-2, it was renamed 9999 Wiles in honour of Andrew J. Wiles, who proved Fermat's last theorem.
    7.00
    5 votes
    29
    1001 Gaussia

    1001 Gaussia

    • Discoverer: Sergei Ivanovich Belyavsky
    • Discovery Site: Simeiz Observatory
    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.
    8.00
    4 votes
    30
    702 Alauda

    702 Alauda

    • Discoverer: Joseph Helffrich
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    702 Alauda is a large minor planet, measuring 194.73 km in diameter. It was discovered in 1910 by Joseph Helffrich from the observatory at Heidelberg University. It is named after the lark (alauda). In 2007, a small moon, named Pichi üñëm, was discovered. Alauda's satellite was discovered from observations using adaptive-optics imaging with the European Southern Observatory (ESO) 8-m Very Large Telescope (VLT) on Cerro Paranal, Chile. It is 5.5 km in diameter and has a projected separation from Alauda of 900 km. It was named Pichi üñëm, meaning "little bird" in the Mapuche language of Chile, the country from which the moon was discovered. Alauda has been identified as the largest member of a dynamical family. Other members of this family include: 581 Tauntonia, 1101 Clematis, 1838 Ursa, 3139 Shantou, 3325 TARDIS, 4368 Pillmore, 5360 Rozhdestvenskij, 5815 Shinsengumi, and many others. Alauda's moon may be a result of the collision that created the asteroid family. The discovery of Alauda's moon enabled Alauda's mass to be determined. Rojo and Margot (2010) have estimated its mass to be 6.06×10 kg with a density of 1.57 g/cm³. Alauda has been observed to occult stars on several
    6.80
    5 votes
    31
    170 Maria

    170 Maria

    • Discoverer: Henri Joseph Anastase Perrotin
    • Discovery Site: Toulouse Observatory
    170 Maria is a Main belt asteroid. It is an S-type asteroid. It is the namesake of the Maria asteroid family. It was discovered by J. Perrotin on January 10, 1877. Its orbit was computed by Antonio Abetti, and the asteroid was named after his sister, Maria. An occultation of a star by Maria was observed from Manitoba, Canada, on June 10, 1997.
    7.50
    4 votes
    32
    4055 Magellan

    4055 Magellan

    • Discoverer: Eleanor F. Helin
    • Discovery Site: Palomar Observatory
    4055 Magellan (1985 DO2) is an Amor asteroid discovered on February 24, 1985, by E. Helin at Palomar.
    7.50
    4 votes
    33
    5D/Brorsen

    5D/Brorsen

    • Discoverer: Theodor 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
    7.50
    4 votes
    34
    9965 GNU

    9965 GNU

    • Discovery Organization: Spacewatch
    • Discovery Site: Kitt Peak National Observatory
    9965 GNU is a C-type main belt asteroid. It orbits the Sun once every 3.76 years. Discovered on March 5, 1992 by Spacewatch, it was given the provisional designation "1992 EF2". It was later renamed "GNU" after the GNU project. Other free-software-related asteroid names:
    7.50
    4 votes
    35
    4183 Cuno

    4183 Cuno

    • Discoverer: Cuno Hoffmeister
    • Discovery Site: Boyden Observatory
    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.
    10.00
    2 votes
    36
    5535 Annefrank

    5535 Annefrank

    • Discoverer: Karl Wilhelm Reinmuth
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    5535 Annefrank /ˌæn ˈfræŋk/ is an inner main-belt asteroid, and member of the Augusta family. It was discovered by Karl Reinmuth in 1942. It is named after Anne Frank, the Dutch-Jewish diarist who died in a concentration camp (the name was not chosen until about 1995). The asteroid was used as a target to practice the flyby technique that the Stardust space probe would later use on the comet Wild 2. Annefrank orbits among the main-belt asteroids, with its shortest axis aligned roughly normal to its orbital plane. On November 2, 2002, the Stardust space probe flew past Annefrank at a distance of 3079 km. Its images show the asteroid to be 6.6 × 5.0 × 3.4 km, twice as big as previously thought, shaped like a triangular prism, with several visible impact craters. From the photographs, the albedo of Annefrank was computed to be between 0.18 and 0.24. Preliminary analysis of the Stardust imagery suggests that Annefrank may be a contact binary, although other possible explanations exist for its observed shape. Later ground based lightcurve data was used in an attempt to measure Annefrank's rotational period. Their data resulted in possible rotational periods of 0.5, 0.63 or 0.95 days,
    6.40
    5 votes
    37
    3 Juno

    3 Juno

    • Discoverer: Karl Ludwig Harding
    • Discovery Site: Lilienthal Observatory
    Juno, formal designation 3 Juno in the Minor Planet Center catalogue system, was the third asteroid to be discovered and is one of the larger main-belt asteroids, being one of the two largest stony (S-type) asteroids, along with 15 Eunomia. It is estimated to contain 1% of the total mass of the asteroid belt. Juno was discovered on September 1, 1804, by German astronomer Karl L. Harding. 3 Juno is named after the mythological Jūno, the highest Roman goddess. The adjectival form is Junonian (jūnōnius). With two exceptions, 'Juno' is the international name, subject to local variation: Italian Giunone, French Junon, Russian Yunona, etc. Its planetary symbol is ③. An older symbol, still occasionally seen, is ⚵ (). Juno is one of the larger asteroids, perhaps tenth by size and containing approximately 1.0% the mass of the entire asteroid belt. It is the second-most-massive S-type asteroid after 15 Eunomia. Though one of the most massive asteroids, Juno has only 3% the mass of Ceres. Amongst S-type asteroids, Juno is unusually reflective, which may be indicative of distinct surface properties. This high albedo explains its relatively high apparent magnitude for a small object not near
    7.25
    4 votes
    38
    511 Davida

    511 Davida

    • Discoverer: Raymond Smith Dugan
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    511 Davida is a large main-belt C-type asteroid. It was discovered by R. S. Dugan in 1903. It is one of the ten most massive asteroids. It is approximately 270–310 km in diameter and comprises an estimated 1.5% of the total mass of the asteroid belt. It is a C-type asteroid, which means that it is dark in colouring with a carbonaceous chondrite composition. Davida is one of the few main-belt asteroids whose shape has been determined by ground-based visual observation. From 2002 to 2007, astronomers at the Keck Observatory used the Keck II telescope, which is fitted with adaptive optics, to photograph Davida. The asteroid is not a dwarf planet: there are at least two promontories and at least one flat facet with 15-km deviations from a best-fit ellipsoid. The facet is presumably a 150-km global-scale crater like the ones seen on 253 Mathilde. Conrad et al. (2007) show that craters of this size "can be expected from the impactor size distribution, without likelihood of catastrophic disruption of Davida." Davida is named after David Peck Todd, an astronomy professor at Amherst College. In 2001, Michalak estimated Davida to have a mass of (6.64±0.56)×10 kg In 2007, Baer and Chesley
    7.25
    4 votes
    39
    87 Sylvia

    87 Sylvia

    • Discoverer: Norman Robert Pogson
    • Discovery Site: Madras Observatory
    87 Sylvia is one of the largest main-belt asteroids. It is a member of the Cybele group located beyond the core of the belt (see minor-planet groups). Sylvia is remarkable for being the first asteroid known to possess more than one moon. Sylvia was discovered by N. R. Pogson on May 16, 1866 from Madras (Chennai), India. A. Paluzie-Borrell, writing in Paul Erget's The Names of the Minor Planets (1955), mistakenly states that the name honours Sylvie Petiaux-Hugo Flammarion, the first wife of astronomer Camille Flammarion. In fact, in the article announcing the discovery of the asteroid, Pogson explained that he selected the name in reference to Rhea Silvia, mother of Romulus and Remus (MNRAS, 1866). Sylvia is very dark in color and probably has a very primitive composition. The discovery of its moons made possible an accurate measurement of the asteroid's mass and density. Its density was found to be very low (around 1.2 times the density of water), indicating that the asteroid is porous to very porous; from 25% to as much as 60% of it may be empty space, depending on the details of its composition. However, the mineralogy of the X-type asteroids is not known well enough to constrain
    7.25
    4 votes
    40
    HD 28185 b

    HD 28185 b

    HD 28185 b is an extrasolar planet approximately 138 light-years away from Earth in the constellation of Eridanus. The planet was discovered orbiting the Sun-like star HD 28185 in April 2001 as a part of the CORALIE survey for southern extrasolar planets, and its existence was independently confirmed by the Magellan Planet Search Survey in 2008. HD 28185 b orbits its sun in a circular orbit that is at the outer edge of its star's habitable zone. Like the majority of known extrasolar planets, HD 28185 b was discovered by detecting small periodic variations in the radial velocity of its parent star caused by the gravitational attraction of the planet. This was achieved by measuring the Doppler shift of the star's spectrum. In 2001 it was announced that HD 28185 exhibited a wobble along the line-of-sight with a period of 383 days, with an amplitude indicating a minimum mass 5.72 times that of Jupiter. HD 28185 b takes 1.04 years to orbit its parent star. Unlike most known long-period planets, the orbit of HD 28185 b has a low eccentricity, comparable to that of Mars in our solar system. The orbit lies entirely within its star's habitable zone. The amplitude of the radial velocity
    7.25
    4 votes
    41
    46P/Wirtanen

    46P/Wirtanen

    • Discoverer: Carl A. 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
    42
    596 Scheila

    596 Scheila

    • Discoverer: August Kopff
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    596 Scheila is a main-belt asteroid and main-belt comet orbiting the Sun. It was discovered on 21 February 1906 by August Kopff from Heidelberg. Kopff named the asteroid after a female English student with whom he was acquainted. On December 11.4 2010, Steve Larson of the Catalina Sky Survey detected a comet-like appearance to asteroid Scheila: it displayed a "coma" of about magnitude 13.5. Inspection of archival Catalina Sky Survey observations showed the activity was triggered between 2010 November 11 and December 3. Imaging with the 2-meter Faulkes Telescope North revealed a linear tail in the anti-sunward direction and an orbital tail, indicative of larger slower particles. When first detected it was unknown what drove the ejecta plumes. Scheila's gravity is too large for electrostatics to launch dust. Cometary outgassing could not be ruled out until detailed spectroscopic observations indicated the absence of gas in Scheila's plumes. Observations by the Hubble Space Telescope and the Swift Gamma Ray Burst Mission's UV-optical telescope make it most likely that Scheila was impacted at ~5 km/s by a previously unknown asteroid ~35 meters in diameter. In 2010, the Hubble Space
    8.33
    3 votes
    43
    67P/Churyumov-Gerasimenko

    67P/Churyumov-Gerasimenko

    Comet Churyumov–Gerasimenko, officially designated 67P/Churyumov–Gerasimenko, is a comet with a current orbital period of 6.45 years. It will next come to perihelion on 13 August 2015. It is the destination of the European Space Agency's Rosetta spacecraft mission, launched on March 2, 2004. The comet was discovered by Klim Ivanovich Churyumov, who examined a photograph that had been exposed for periodic comet 32P/Comas Solá by Svetlana Gerasimenko on September 11, 1969 at the Alma-Ata Astrophysical Institute. Churyumov found a cometary object near the edge of the plate, but assumed that this was Comas Solá. After returning to his home institute in Kiev, Churyumov examined all the photographic plates more closely. About a month after the photograph was taken (October 22), he discovered that the object could not be Comas Solá, because it was about 1.8 degrees off the expected position. Further scrutiny produced a faint image of Comas Solá at its expected position on the plate, thus proving that the other object was a newly discovered comet. As preparation for the Rosetta mission, Hubble Space Telescope pictures taken on March 12, 2003, were closely analyzed. An overall 3-D model was
    8.33
    3 votes
    44
    951 Gaspra

    951 Gaspra

    • Discoverer: Grigory Nikolaevich Neujmin
    • Discovery Site: Simeiz Observatory
    951 Gaspra ( /ˈɡæsprə/) is an S-type asteroid that orbits very close to the inner edge of the asteroid belt. Gaspra was the first asteroid ever to be closely approached when it was visited by the Galileo spacecraft, which flew by on its way to Jupiter on 29 October 1991. Apart from a multitude of small craters, Gaspra has half a dozen large flat areas and concavities. One of these flat areas, (Dunne Regio), is a 5×7 km area which is flat to within 200 m. It is uncertain whether these are the result of impacts or whether they are instead facets formed when Gaspra broke off its parent asteroid. In the weak, lopsided gravity of Gaspra, impact craters would naturally take on such flat, lopsided shapes, making this determination difficult. The flat facets and concavities give Gaspra a very angular appearance. Gaspra appears to be fairly olivine-rich among the S-type asteroids (the surface appears to contain olivine and pyroxene in the proportions 4:1 to 7:1). There are no prominent albedo or color patterns, although a subtle color variation is seen across the surface (see image above). Gaspra's surface lacks unambiguous craters of a size comparable to its radius, like those seen for
    8.33
    3 votes
    45
    9988 Erictemplebell

    9988 Erictemplebell

    • Discoverer: Paul G. Comba
    • Discovery Site: Prescott Observatory
    9988 Erictemplebell is a main belt asteroid. It orbits the Sun once every 4.94 years. Discovered on September 9, 1997 by Paul G. Comba, it was given the provisional designation 1997 RX6. It was later renamed 9988 Erictemplebell in honour of Eric Temple Bell, a professor at the California Institute of Technology where he taught a class on algebra which the discoverer took.
    8.33
    3 votes
    46
    1221 Amor

    1221 Amor

    • Discoverer: Eugène Joseph Delporte
    • Discovery Site: Observatoire Royal de Belgique
    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.
    9.50
    2 votes
    47
    15017 Cuppy

    15017 Cuppy

    • Discoverer: Edward L. G. Bowell
    • Discovery Organization: Lowell Observatory Near-Earth-Object Search
    • Discovery Site: Anderson Mesa Station
    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.
    9.50
    2 votes
    48
    15462 Stumegan

    15462 Stumegan

    • Discovery Organization: Spacewatch
    • Discovery Site: Kitt Peak National Observatory
    15462 Stumegan (1999 AV1) is a Main-belt asteroid discovered on January 8, 1999. The asteroid was discovered at Kitt Peak National Observatory as part of the Spacewatch project. It is named for Stu Megan, who discovered the first Spacewatch FMO Project asteroid to attain an official IAU MPEC designation.
    9.50
    2 votes
    49
    Ceres

    Ceres

    • Discoverer: Giuseppe Piazzi
    • Discovery Site: Osservatorio Astronomico di Palermo "Giuseppe S. Vaiana"
    Ceres, formally 1 Ceres, is the only dwarf planet in the inner Solar System, and the largest asteroid. It is a rock–ice body 950 km (590 mi) in diameter, and though the smallest identified dwarf planet, it constitutes a third of the mass of the asteroid belt. Discovered on 1 January 1801 by Giuseppe Piazzi, it was the first asteroid to be identified, though it was classified as a planet at the time. It is named after Ceres, the Roman goddess of growing plants, the harvest, and motherly love. The Cererian surface is probably a mixture of water ice and various hydrated minerals such as carbonates and clays. It appears to be differentiated into a rocky core and icy mantle, and may harbour an ocean of liquid water under its surface. From Earth, the apparent magnitude of Ceres ranges from 6.7 to 9.3, and hence even at its brightest it is still too dim to be seen with the naked eye except under extremely dark skies. The unmanned Dawn spacecraft, launched on 27 September 2007 by NASA, is expected to be the first to explore Ceres after its scheduled arrival there in 2015. The spacecraft left asteroid 4 Vesta about 5 September 2012, which it had been orbiting since July 2011. The idea that
    9.50
    2 votes
    50
    14827 Hypnos

    14827 Hypnos

    • Discoverer: Carolyn S. Shoemaker
    14827 Hypnos (also known by its provisional designation 1986 JK) is an Apollo near-Earth asteroid (NEA) discovered by Carolyn S. Shoemaker and Eugene Merle Shoemaker at Palomar Observatory on May 5, 1986. It is named after Hypnos, the Greek god of sleep. Hypnos may be the nucleus of an extinct comet that is covered by a crust several centimeters thick that prevents any remaining volatiles from outgassing. Hypnos is frequently perturbed by Jupiter. In 1958, Hypnos passed less than 0.03 AU from both Earth and Mars. Neither planet has been approached so closely by Hypnos since the 862 pass of Earth, or will be until the 2214 pass of Earth. It has a well determined orbit and has been observed 170 times since 1986.
    7.00
    4 votes
    51
    9991 Anezka

    9991 Anezka

    • Discoverer: Zdeněk Moravec
    • Discovery Site: Kleť Observatory
    9991 Anežka is an outer main belt asteroid. It orbits the Sun once every 5.73 years. Discovered on October 5, 1997 by Zdeněk Moravec, it was given the provisional designation 1997 TY9. It was later renamed 9991 Anežka to honour the grandmother of its discoverer for her 75th birthday.
    7.00
    4 votes
    52
    Comet Morehouse

    Comet Morehouse

    • Discoverer: Daniel Walter 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.
    7.00
    4 votes
    53
    Neptune

    Neptune

    • Discoverer: Dr Galle
    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
    7.00
    4 votes
    54
    1036 Ganymed

    1036 Ganymed

    • Discoverer: Walter Baade
    • Discovery Site: Hamburg-Bergedorf Observatory
    1036 Ganymed is the largest Amor asteroid, at about 32 km in diameter. It was discovered by Walter Baade on October 23, 1924. It has a very well determined orbit, and its next pass of the Earth will be at a distance of 0.374097 AU (55,964,100 km; 34,774,500 mi) on 13 October 2024. It is also a Mars-crosser asteroid, and will pass 0.02868 AU (4,290,000 km; 2,666,000 mi) from Mars on 16 December 2176. Ganymed is the German spelling of Ganymede, the Trojan prince turned god whom Zeus designated the cupbearer to the Greek gods. Jupiter's moon Ganymede is named after the same, but uses the English spelling. Owing to its early discovery date, Ganymed has a rich observational history. A 1931 paper published the absolute magnitude, based on observations to date, as 9.24, slightly brighter than the present value of 9.45. Ganymed is an S-type asteroid, meaning that it is relatively reflective and composed of iron and magnesium silicates. Spectral measurements put Ganymed in the S (VI) spectral subtype, indicating a surface rich in orthopyroxenes, and possibly metals (although if metals are present they are covered and not readily apparent in the spectra). In 1998, radar observations of
    8.00
    3 votes
    55
    3806 Tremaine

    3806 Tremaine

    • Discoverer: Schelte J. Bus
    • Discovery Site: Siding Spring Observatory
    3806 Tremaine is a small asteroid of the Alinda family. It was first sighted on 14 October 1975 and given the provisional designation 1975 TY5. Two more sightings occurred (1979 SC11 and 1979 TL2) before the March 1, 1981 sighting by Schelte J. Bus (provisional designation 1981 EW32) finally nailed down the orbit. It is named for the noted Canadian astrophysicist Scott Tremaine.
    8.00
    3 votes
    56
    90 Antiope

    90 Antiope

    • Discoverer: Karl Theodor Robert Luther
    • Discovery Site: Düsseldorf-Bilk Observatory
    90 Antiope ( /ænˈtaɪ.əpiː/ an-TY-ə-pee) is a double asteroid in the outer asteroid belt. It was discovered on October 1, 1866, by Robert Luther. In 2000 it was found to consist of two almost-equally-sized bodies orbiting each other. At average diameters of about 88 km and 84 km, both components are among the 500 largest asteroids. Antiope is part of the Themis family. The number in 90 Antiope's name denotes that it was the 90th asteroid to be discovered. Its proper name comes from Greek mythology, though it is disputed as to whether this is Antiope the Amazon or Antiope the mother of Amphion and Zethus. Since the discovery of Antiope's binary nature, the name "Antiope" technically refers to the slightly larger of the two components, with the smaller component bearing the provisional designation S/2000 (90) 1. However, the name "Antiope" is also used to refer to the binary system as a whole. The most remarkable feature of Antiope is that it consists of two components of almost equal size (the difference in mass is less than 2.5%), making it a truly "double" asteroid. Its binary nature was discovered on 10 August 2000 by a group of astronomers using adaptive optics at the Keck
    8.00
    3 votes
    57
    906 Repsolda

    906 Repsolda

    • Discoverer: Friedrich Karl Arnold Schwassmann
    • Discovery Site: Hamburg-Bergedorf Observatory
    906 Repsolda is a minor planet orbiting the Sun. It is named for the German astronomer and fireman Johann Georg Repsold (1770-1830) who founded and ran Hamburg Observatory.
    8.00
    3 votes
    58
    9983 Rickfienberg

    9983 Rickfienberg

    • Discoverer: Dennis di Cicco
    • Discovery Site: Sudbury observatory
    9983 Rickfienberg is a main belt asteroid. It orbits the Sun once every 4.45 years. Discovered on February 19, 1995 by Dennis di Cicco, it was given the provisional designation 1995 DA. It was later renamed 9983 Rickfienberg after Richard Tresch Fienberg, the editor of Sky & Telescope at the time.
    8.00
    3 votes
    59
    Comet McNaught

    Comet McNaught

    Comet McNaught, also known as the Great Comet of 2007 and given the designation C/2006 P1, is a non-periodic comet discovered on August 7, 2006 by British-Australian astronomer Robert H. McNaught. It was the brightest comet in over 40 years, and was easily visible to the naked eye for observers in the Southern Hemisphere in January and February 2007. With an estimated peak magnitude of -5.5, the comet was the second brightest since 1935. Around perihelion on January 12, it was visible worldwide in broad daylight. Its tail measured an estimated 35 degrees in length at its peak. The brightness of C/2006 P1 near perihelion was enhanced by forward scattering. McNaught discovered the comet in a CCD image on August 7, 2006 during the course of routine observations for the Siding Spring Survey, which searches for Near-Earth Objects that might represent a collision threat to Earth. The comet was discovered in Ophiuchus, shining very dimly at a magnitude of about +17. From August through November 2006, the comet was imaged and tracked as it moved through Ophiuchus and Scorpius, brightening as high as magnitude +9, still too dim to be seen with the unaided eye. Then, for most of December,
    8.00
    3 votes
    60
    Gliese 876 c

    Gliese 876 c

    • Discoverer: Geoffrey Marcy
    Gliese 876 c is an extrasolar planet orbiting the red dwarf star Gliese 876, taking about 30 days to complete an orbit. The planet was discovered in April 2001 and is the second planet in order of increasing distance from its star. At the time of discovery, Gliese 876 was already known to host an extrasolar planet designated Gliese 876 b. In 2001, further analysis of the star's radial velocity revealed the existence of a second planet in the system, which was designated Gliese 876 c. The orbital period of Gliese 876 c was found to be exactly half that of the outer planet, which meant that the radial velocity signature of the second planet was initially interpreted as a higher eccentricity of the orbit of Gliese 876 b. Gliese 876 c is in a 1:2:4 Laplace resonance with the outer planets Gliese 876 b and Gliese 876 e: for every orbit of planet e, planet b completes two orbits and planet c completes four. This leads to strong gravitational interactions between the planets, causing the orbital elements to change rapidly as the orbits precess. This is the second known example of a Laplace resonance, the first being Jupiter's moons Io, Europa and Ganymede. The orbital semimajor axis is
    8.00
    3 votes
    61
    OGLE-TR-10 b

    OGLE-TR-10 b

    • Discovery Organization: Optical Gravitational Lensing Experiment
    OGLE-TR-10b is an extrasolar planet orbiting the star OGLE-TR-10. The planet was first detected by the Optical Gravitational Lensing Experiment (OGLE) survey in 2002. The star, OGLE-TR-10, was seen dimming by a tiny amount every 3 days. The transit lightcurve resembles that of HD 209458 b, the first transiting extrasolar planet. However, the mass of the object had to be measured by the radial velocity method, because other objects like red dwarfs and brown dwarfs can mimic the planetary transit. In late 2004 it was confirmed as the 5th planetary discovery by OGLE. The planet is a typical "hot Jupiter", a planet with a mass half that of Jupiter and orbital distance only 1/24th that of Earth from the Sun. One revolution around the star takes a little over three days to complete. The planet is slightly larger than Jupiter, probably due to the heat from the star. OGLE-TR-10 was identified as a promising candidate by the OGLE team during their 2001 campaign in three fields towards the Galactic Center. The possible planetary nature of its companion was based on spectroscopic follow-up. A reported a tentative radial velocity semi-amplitude (from Keck-I/HIRES) of 100+/-43 m/s, and a mass
    8.00
    3 votes
    62
    R Leporis

    R Leporis

    • Discoverer: John Russell Hind
    R Leporis (R Lep), sometimes called Hind's Crimson Star, is a well-known variable star in the constellation Lepus, near its border with Eridanus. It is designated "R" in the chart to the right. It is a carbon star which appears distinctly red. It is named after famous British astronomer J. R. Hind, who observed it in 1845. Its apparent magnitude varies from +5.5 to +11.7 with a period of 418–441 days, although recent measurements give a period of 427.07 days. There may be a secondary period of 40 years. R Leporis has often been reported as an intense smoky red color, although this is not pronounced when the star is near its maximum brightness. It is reddest when it is dimmest, which occurs every 14.5 months. During these periods it is a candidate for the most-visible reddest star, but this claim is questionable. The red coloration may be caused by carbon in the star's outer atmosphere filtering out the blue part of its visible light spectrum. The star's discoverer, Hind, reported that it appeared "like a drop of blood on a black field."
    8.00
    3 votes
    63
    9975 Takimotokoso

    9975 Takimotokoso

    • Discoverer: Kazuro Watanabe
    • Discovery Site: Kitami Observatory
    9975 Takimotokoso is a main belt asteroid. It orbits the Sun once every 3.86 years. Discovered on September 12, 1993 by K. Endate and K. Watanabe it was given the provisional designation 1993 RZ1. It was later renamed Takimotokoso after Koso Takimoto, the associate president of the Hiroshima Astronomical Society.
    6.75
    4 votes
    64
    Comet Borrelly

    Comet Borrelly

    • Discoverer: Alphonse Louis Nicolas 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.
    6.75
    4 votes
    65
    Orionids

    Orionids

    • Discoverer: Alexander Stewart Herschel
    The Orionid meteor shower, usually shortened to the Orionids, is the most prolific meteor shower associated with Halley's Comet. The Orionids are so-called because the point they appear to come from, called the radiant, lies in the constellation Orion. Orionids are an annual meteor shower which last approximately one week in late-October. In some years, meteors may occur at rates of 50-70 per hour. Meteor showers first designated "shooting stars" were connected to comets in the 1800s. E.C. Herrick made an observation in 1839 and 1840 about the activity present in the October night skies. However A.S. Herschel produced the first documented record which produced accurate forecasts for the next meteor shower. The Orionid meteor shower is produced by the well-known Halley's Comet, which was named after the astronomer Edmund Halley and last passed through the inner solar system in 1986 on its 75-to-76-year orbit. When the comet passes through the solar system, the sun sublimates some of the ice which allows rock particles to break away from the comet. These particles continue on the comet's trajectory and appear as meteors or "falling stars" when they pass through Earth's upper
    6.75
    4 votes
    66
    (9981) 1995 BS3

    (9981) 1995 BS3

    • Discoverer: Takao Kobayashi
    • Discovery Site: Oizumi Observatory
    (9981) 1995 BS3 is a main belt asteroid. It orbits the Sun once every 4.38 years. Discovered on January 31, 1995 by T. Kobayashi, it was given the provisional designation 1995 BS3.
    9.00
    2 votes
    67
    16 Psyche

    16 Psyche

    • Discoverer: Annibale de Gasparis
    • Discovery Site: Astronomical Observatory of Capodimonte
    16 Psyche is one of the ten most massive main-belt asteroids. It is over 200 kilometers in diameter and contains a little less than 1% of the mass of the entire asteroid belt. It is the most massive metallic M-type asteroid. Psyche was discovered by Annibale de Gasparis on March 17, 1852 from Naples and named after the Greek mythological figure Psyche. The first fifteen asteroids to be discovered were given symbols by astronomers as a type of short-hand notation. In 1851, however, J. F. Encke suggested using a circled number. 16 Psyche was the first new asteroid to be discovered that was designated with this scheme (in 1852 by J. Ferguson). Radar observations indicate a fairly pure iron–nickel composition. Psyche appears to be a genuine case of an exposed metallic core from a larger differentiated parent body. Unlike some other M-type asteroids, Psyche shows no sign of the presence of water or water-bearing minerals on its surface, consistent with its interpretation as a metallic body. Small amounts of pyroxene appear to be present. If Psyche is the core remnant of a larger parent body, we might expect other asteroids on similar orbits. Psyche does not belong to any asteroid
    9.00
    2 votes
    68
    2002 JF56

    2002 JF56

    132524 APL (previously known by its provisional designation, 2002 JF56) is a small asteroid about 2.3 kilometers across visited by the New Horizons probe, which passed it at about 101,867 km at 04:05 UTC on June 13, 2006. The spectra obtained by New Horizons shows that APL is an S-type asteroid. Alan Stern, principal investigator for New Horizons, named the asteroid in reference to the Johns Hopkins Applied Physics Lab, which runs the mission.
    9.00
    2 votes
    69
    298 Baptistina

    298 Baptistina

    • Discoverer: Auguste Charlois
    • Discovery Site: Nice Observatory
    298 Baptistina is an asteroid orbiting in the asteroid belt and part of the Baptistina family of asteroids. It was discovered on September 9, 1890 by Auguste Charlois of Nice. The reason for its name is unknown. It measures around 13–30 km in diameter. Although it has an orbit similar to the Flora family asteroids, Baptistina was found to be an unrelated interloper. It was considered the possible source of the impactor said to have caused the extinction of the dinosaurs, a possibility ruled out by the Wide-field Infrared Survey Explorer in 2011. In 2007, a study by William F. Bottke, David Vokrouhlický and David Nesvorný proposed that several known asteroids can be regarded as the "Baptistina family" because they share similar orbital elements. Further, the study argues that the family is the remnant of a 170 km (110 mi) parent asteroid that was destroyed in a collision with a smaller body some 80 million years ago, with Baptistina itself being the largest remnant. Until recently, it was believed that this collision event occurred 160 million years ago. This led to a suggestion that one fragment from the event may have eventually become the K–T impactor believed to have caused the
    9.00
    2 votes
    70
    Deimos

    Deimos

    • Discoverer: Asaph Hall
    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
    9.00
    2 votes
    71
    TrES-1

    TrES-1

    • Discovery Organization: Trans-Atlantic Exoplanet Survey
    TrES-1b is an extrasolar planet approximately 512 light-years away in the constellation of Lyra (the Lyre). The planet's mass and radius indicate that it is a Jovian planet with a similar bulk composition to Jupiter. Unlike Jupiter, but similar to many other planets detected around other stars, TrES-1 is located very close to its star, and belongs to the class of planets known as hot Jupiters. The planet was discovered orbiting around GSC 02652-01324 (an orange dwarf star). TrES-1b was discovered by the Trans-Atlantic Exoplanet Survey by detecting the transit of the planet across its parent star using a 4-inch-diameter (100 mm) telescope. The discovery was confirmed by the Keck Observatory. The planet was subsequently detected using the radial velocity method, allowing its mass to be determined. On March 22, 2005, Astronomers using NASA's Spitzer Space Telescope took advantage of this fact to directly capture the infrared light of two previously detected planets orbiting outside our solar system. Their findings revealed the temperatures and orbits of the planets. Upcoming Spitzer observations using a variety of infrared wavelengths may provide more information about the planets'
    9.00
    2 votes
    72
    9950 ESA

    9950 ESA

    • Discoverer: Christian Pollas
    • Discovery Site: Centre de recherches en géodynamique et astrométrie
    9950 ESA is an Amor asteroid. It orbits the Sun once every 3.81 years. Discovered on November 8, 1990 by C. Pollas it was given the provisional designation "1990 VB". It was later renamed "ESA" after the European Space Agency.
    5.80
    5 votes
    73
    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
    5.80
    5 votes
    74
    1998 KY26

    1998 KY26

    • Discoverer: Tom Gehrels
    • Discovery Organization: Spacewatch
    The asteroid 1998 KY26 (also written 1998 KY26) was discovered on June 2, 1998, by Spacewatch and observed until June 8, when it passed 800,000 kilometers (half a million miles) away from Earth (a little more than twice the Earth-Moon distance). It is roughly spherical and is only about 30 metres (98 ft) in diameter. Although it is nearly small enough be classified a meteoroid, the most common definition uses a diameter of 10 m as the demarcation, just making 1998 KY26 an asteroid. Because of this, as all the other objects smaller than 1998 KY26 are under 10 meters in diameter, this makes 1998 KY26 the smallest asteroid, the largest being Ceres. With a rotation period of 10.7 minutes it has one of the shortest sidereal days of any known object in the solar system, and cannot possibly be a rubble pile. It is also one of the most easily accessed objects in the solar system, and its orbit frequently brings it on a path very similar to the optimum Earth-Mars transfer orbit. This, coupled with the fact that it is water rich, makes it an attractive target for further study and a potential source of water for future missions to Mars. The discovery is attributed to an international team of
    7.67
    3 votes
    75
    216 Kleopatra

    216 Kleopatra

    • Discoverer: Johann Palisa
    • Discovery Site: Pola Observatory
    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
    7.67
    3 votes
    76
    7 Iris

    7 Iris

    • Discoverer: John Russell Hind
    • Discovery Site: George Bishop's Observatory, Regent's Park
    7 Iris is a large main-belt asteroid. Among the S-type asteroids, it ranks fifth in geometric mean diameter after Eunomia, Juno, Amphitrite and Herculina. Its bright surface and small distance from the Sun make Iris the fourth brightest object in the asteroid belt after Vesta, Ceres, and Pallas. But at typical oppositions it marginally outshines the larger though darker Pallas. It has a mean opposition magnitude of +7.8, comparable to that of Neptune, and can easily be seen with binoculars at most oppositions. At rare oppositions near perihelion Iris can reach a magnitude of +6.7 (next time on October 31, 2017 reaching a magnitude of +6.9), which is as bright as Ceres ever gets; reports of it being seen without optical aid are unverified. It was the seventh asteroid discovered, on August 13, 1847, by J. R. Hind from London, UK. It was Hind's first asteroid discovery. Iris was named after the rainbow goddess Iris of Greek mythology, sister of the Harpies and messenger of the gods, especially Hera. Her quality of attendant of Hera was particularly appropriate to the circumstances of discovery, as she was spotted following 3 Juno (Juno is the Roman equivalent of Hera) by less than an
    7.67
    3 votes
    77
    (145453) 2005 RR43

    (145453) 2005 RR43

    (145453) 2005 RR43, also written as (145453) 2005 RR43, is a trans-Neptunian object (TNO) estimated to be about 252 km in diameter. It was discovered by Andrew C. Becker, Andrew W. Puckett, and Jeremy Martin Kubica on September 9, 2005 at Apache Point Observatory in Sunspot, New Mexico. Based on their common pattern of IR water-ice absorptions and neutral visible spectrum, and the clustering of their orbital elements, the KBOs (145453) 2005 RR43, 1995 SM55, (19308) 1996 TO66, (55636) 2002 TX300, and (120178) 2003 OP32 appear to be collisional fragments broken off the dwarf planet Haumea. The surface is covered by water ice as attested by deep absorption at 1.5 and 2 μm in the infrared spectrum and neutral (i.e. non-red) colour. Scattering models reveal that the observed water ice is, at least in a significant fraction, crystalline and organics, detected on the surface of many TNO, are completely absent. These physical and orbital characteristics common with Haumea led to suggestion that 2005 RR43 is a member of the Haumea collisional family. The object, together with other members of the family ((19308) 1996 TO66, (24835) 1995 SM55, (55636) 2002 TX300, and (120178) 2003 OP32),
    10.00
    1 votes
    78
    (9982) 1995 CH

    (9982) 1995 CH

    • Discoverer: Takao Kobayashi
    • Discovery Site: Oizumi Observatory
    (9982) 1995 CH is a main belt asteroid. It orbits the Sun once ever 4.41 years. Discovered on February 1, 1995 by T. Kobayashi, it was given the provisional designation 1995 CH.
    10.00
    1 votes
    79
    Phobos

    Phobos

    • Discoverer: Asaph Hall
    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
    10.00
    1 votes
    80
    (9952) 1991 AK

    (9952) 1991 AK

    • Discoverer: Hiroshi Mori
    • Discovery Site: Yorii Observatory
    (9952) 1991 AK is a main belt asteroid. It orbits the Sun once every 4.33 years. Discovered on January 9, 1991 by M. Arai and Hiroshi Mori, it was given the provisional designation "1991 AK".
    6.50
    4 votes
    81
    Flora family

    Flora family

    The Flora family of asteroids is a large grouping of S-type asteroids in the inner main belt, whose origin and properties are relatively poorly understood at present. Roughly 4-5% of all main belt asteroids belong to this family. Because of its poorly defined boundaries, and the location of Flora itself near the edge, this asteroid group has also sometimes been called the Ariadne family, when Flora did not make it into the group during an analysis (e.g. the WAM analysis by Zappala 1995). The Flora family of asteroids may be the source of the Chicxlub (Cretaceous–Paleogene) impactor, the likely culprit in the extinction of the dinosaurs. The largest member is 8 Flora, which meaures 140 km in diameter, and comprises about 80% of the total family mass. Nevertheless, the parent body was almost certainly disrupted by the impact/s that formed the family, and Flora is probably a gravitational aggregate of most of the pieces. 43 Ariadne makes up much of the remaining mass (about a further 9%), with the remaining family members being fairly small, below 30 km in diameter. A noticeable fraction of the parent body has been lost from the family since the original impact, presumably due to
    5.60
    5 votes
    82
    10515 Old Joe

    10515 Old Joe

    • Discoverer: Brian G. W. Manning
    • Discovery Site: Stakenbridge Observatory
    10515 Old Joe is a main-belt asteroid discovered by Brian G. W. Manning on October 31, 1989 from Stakenbridge, in the village of Churchill, near Kidderminster, Worcestershire, England. It is named after the Joseph Chamberlain Memorial Clock Tower (nicknamed Old Joe) at the University of Birmingham.
    8.50
    2 votes
    83
    OGLE-2005-BLG-390L b

    OGLE-2005-BLG-390L b

    OGLE-2005-BLG-390Lb is a 'super-Earth' extrasolar planet orbiting the star OGLE-2005-BLG-390L, which is situated 21,500 ± 3,300 light years away from Earth, near the center of the Milky Way galaxy. On January 25, 2006, Probing Lensing Anomalies NETwork/Robotic Telescope Network (PLANET/Robonet), Optical Gravitational Lensing Experiment (OGLE), and Microlensing Observations in Astrophysics (MOA) made a joint announcement of the discovery. The planet does not appear to meet conditions presumed necessary to support life. OGLE-2005-BLG-390Lb orbits around its star at an average distance of 2.0 to 4.1 AU, or an orbit that would fall between the orbits of Mars and Jupiter in our own solar system. (This range of distances is the range of error in measurement and calculation; it does not represent the planet's orbital eccentricity, as its orbital elements are not known.) Until this discovery, no small exoplanet had been found farther than 0.15 AUs from a main sequence star. The planet takes approximately 10 Earth years to orbit its star, OGLE-2005-BLG-390L. OGLE-2005-BLG-390Lb's sun (located in the constellation Scorpius, RA 17:54:19.2, Dec −30°22′38″, J2000, 6.6 ± 1.0 kpc distance) is
    8.50
    2 votes
    84
    12 Victoria

    12 Victoria

    • Discoverer: John Russell Hind
    • Discovery Site: George Bishop's Observatory, Regent's Park
    12 Victoria is a large main-belt asteroid. It was discovered by J. R. Hind on September 13, 1850. Victoria is officially named after the Roman goddess of victory, but the name also honours Queen Victoria. The goddess Victoria (Nike for the Greeks) was the daughter of Styx by the Titan Pallas. The coincidence with the name of the then-reigning queen caused quite a controversy at the time, and B. A. Gould, editor of the prestigious Astronomical Journal, adopted the alternate name Clio (now used by 84 Klio), proposed by the discoverer. However, W. C. Bond, of the Harvard College Observatory, then the highest authority on astronomy in America, held that the mythological condition was fulfilled and the name therefore acceptable, and his opinion eventually prevailed. Radar and speckle interferometry observations show that the shape of Victoria is elongated, and it is suspected to be a binary asteroid. Victoria has only ever been observed to occult a star thrice since its discovery.
    7.33
    3 votes
    85
    2007 WD5

    2007 WD5

    • Discoverer: Andrea Boattini
    • Discovery Organization: Catalina Sky Survey
    2007 WD5 is a 50 m (160 ft) diameter Apollo class near-Earth object and a Mars-crosser asteroid discovered on November 20, 2007, by Andrea Boattini of the Catalina Sky Survey. Early observations of 2007 WD5 caused excitement amongst the scientific community when it was estimated as having as high as a 1 in 25 chance of colliding with Mars on January 30, 2008. However, by January 9, 2008, additional observations allowed NASA's Near Earth Object Program (NEOP) to reduce the uncertainty region resulting in only a 1-in-10,000 chance of impact. 2007 WD5 most likely passed Mars at a distance of 6.5 Mars radii. Due to this relatively small distance and the uncertainty level of the prior observations, the gravitational effects of Mars on its trajectory are unknown and, according to Steven Chesley of NASA's Jet Propulsion Laboratory Near-Earth Object program, 2007 WD5 is currently considered 'lost' (see lost asteroids). The asteroid was discovered on November 20, 2007 by Andrea Boattini of the NASA-funded Catalina Sky Survey on Mount Lemmon, near Tucson, Arizona, USA, using a 1.5m telescope. It was discovered in the constellation Taurus at an apparent magnitude of +20. This is about 400,000
    7.33
    3 votes
    86
    9 Metis

    9 Metis

    • Discoverer: Andrew Graham
    • Discovery Site: Markree Observatory
    9 Metis is one of the larger main-belt asteroids. It is composed of silicates and metallic nickel-iron, and may be the core remnant of a large asteroid that was destroyed by an ancient collision. Metis is estimated to contain just under half a percent of the total mass of the asteroid belt. Metis was discovered by Andrew Graham on 25 April 1848, at Markree Observatory in Ireland; it was his only asteroid discovery. It also has been the only asteroid to have been discovered as a result of observations from Ireland until 7 October 2008, when, 160 years later, Dave McDonald from observatory J65 discovered 2008 TM9. Its name comes from the mythological Metis, a Titaness and Oceanid, daughter of Tethys and Oceanus. The name Thetis was also considered and rejected (it would later devolve to 17 Thetis). Metis' direction of rotation is unknown at present, due to ambiguous data. Lightcurve analysis indicates that the Metidian pole points towards either ecliptic coordinates (β, λ) = (23°, 181°) or (9°, 359°) with a 10° uncertainty. The equivalent equatorial coordinates are (α, δ) = (12.7 h, 21°) or (23.7 h, 8°). This gives an axial tilt of 72° or 76°, respectively. Hubble space telescope
    7.33
    3 votes
    87
    9941 Iguanodon

    9941 Iguanodon

    • Discoverer: Eric Walter Elst
    • Discovery Site: La Silla Observatory
    9941 Iguanodon is an S-type main belt asteroid which orbits the Sun every 3.49 years. It was discovered on February 4, 1989 by Eric Elst at the European Southern Observatory and given the provisional designation "1989 CB3". It was later renamed "Iguanodon" after the dinosaur genus Iguanodon.
    7.33
    3 votes
    88
    9987 Peano

    9987 Peano

    • Discoverer: Paul G. Comba
    • Discovery Site: Prescott Observatory
    9987 Peano is a main belt asteroid. It orbits the Sun once every 3.38 years. Discovered by P. G. Comba on July 29, 1997 it was given the provisional designation 1997 OO1. It was later renamed 9987 Peano in honour of Giuseppe Peano.
    7.33
    3 votes
    89
    Comet Kirch (1680)

    Comet Kirch (1680)

    C/1680 V1, also called the Great Comet of 1680, Kirch's Comet, and Newton's Comet, has the distinction of being the first comet discovered by telescope. Discovered by Gottfried Kirch on 14 November 1680, New Style, it became one of the brightest comets of the 17th century – reputedly visible even in daytime – and was noted for its spectacularly long tail. Passing only 0.42 AUs from Earth on 30 November, it sped around an incredibly close perihelion of 0.0062 AU (930,000 km; 580,000 mi) on 18 December 1680, reaching its peak brightness on 29 December as it rushed outward again. It was last observed on 19 March 1681. As of September 2012 the comet was about 253 AU from the Sun. While the Kirch Comet of 1680-1681 was discovered and subsequently named for Gottfried Kirch, credit must also be given to Eusebio Kino, the spaniard Jesuit priest who charted the comet’s course. During his delayed departure for Mexico, Kino began his observations of the comet in Cadíz in late 1680. Upon his arrival in Mexico City, he published his Exposisión [sic] astronómica de el cometa (Mexico City, 1681) in which he presented his findings. Kino’s Exposisión astronómica is among one of the earliest
    7.33
    3 votes
    90
    Galilean moons

    Galilean moons

    The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei in January 1610. They are the largest of the many moons of Jupiter and derive their names from the lovers of Zeus: Io, Europa, Ganymede, and Callisto. They are among the most massive objects in the Solar System outside the Sun and the eight planets, with radii larger than any of the dwarf planets. The three inner moons – Ganymede, Europa, and Io – participate in a 1:2:4 orbital resonance. The four moons were discovered sometime between 1609 and 1610 when Galileo made improvements to his telescope, which enabled him to observe celestial bodies more distinctly than had ever been possible before. Galileo’s discovery showed the importance of the telescope as a tool for astronomers by proving that there were objects in space that cannot be seen by the naked eye. More importantly, the incontrovertible discovery of celestial bodies orbiting something other than the Earth dealt a serious blow to the then-accepted Ptolemaic world system, or the geocentric theory in which everything orbits around the Earth. Galileo initially named his discovery the Cosmica Sidera ("Cosimo's stars"), but names that eventually
    6.25
    4 votes
    91
    Gliese 876 b

    Gliese 876 b

    • Discoverer: Geoffrey Marcy
    Gliese 876 b is an extrasolar planet orbiting the red dwarf star Gliese 876. It completes one orbit in approximately 61 days. Discovered in June 1998, Gliese 876 b was the first planet to be discovered orbiting a red dwarf star. Gliese 876 b was discovered independently by two different teams, one led by Geoffrey Marcy (with data from Keck Observatory and Lick Observatory) and the other by Xavier Delfosse (at Geneva Observatory). Like the majority of known extrasolar planets, it was discovered by detecting variations in its star's radial velocity as a result of the planet's gravity. This was done by making sensitive measurements of the Doppler shift of the spectral lines of Gliese 876. It was the first discovered of four known planets in the Gliese 876 system. Gliese 876 b is in a 1:2:4 Laplace resonance with the inner planet Gliese 876 c and the outer planet Gliese 876 e: in the time it takes planet e to complete one orbit, planet b completes two and planet c completes four. This is the second known example of a Laplace resonance, the first being Jupiter's moons Io, Europa and Ganymede. As a result, the orbital elements of the planets change fairly rapidly as they dynamically
    6.25
    4 votes
    92
    15779 Scottroberts

    15779 Scottroberts

    • Discoverer: Carolyn S. Shoemaker
    • Discovery Site: Palomar Observatory
    15779 Scottroberts is a main belt asteroid. Discovered on July 26, 1993 by Carolyn S. Shoemaker and David H. Levy at Palomar Observatory with the 18" Schmidt Camera, it was originally designated 1993 OA3. Also known as a minor planet or planetoid, 1993 OA3 was renamed by the discoverers for Scott W. Roberts (born 1959), who for many years has encouraged amateur astronomers to pursue their love of the night sky, spending much time teaching people how to use and enjoy their telescopes.
    5.40
    5 votes
    93
    21 Lutetia

    21 Lutetia

    • Discoverer: Hermann Mayer Salomon Goldschmidt
    • Discovery Site: Paris Observatory
    21 Lutetia is a large main-belt asteroid of an unusual spectral type. It measures about 100 kilometers in diameter (120 km along its major axis). It was discovered in 1852 by Hermann Goldschmidt, and is named after Lutetia, the Latin name of the city that stood where Paris was later built. Lutetia has an irregular shape and is heavily cratered, with the largest impact crater reaching 45 km in diameter. The surface is geologically heterogeneous and is intersected by a system of grooves and scarps, which are thought to be fractures. It has a high average density, meaning that it is made of metal-rich rock. The Rosetta probe passed within 3,162 km (1,965 mi) of Lutetia in July 2010. It was the largest asteroid visited by a spacecraft until the Dawn mission arrived at 4 Vesta in July 2011. Lutetia was discovered on November 15, 1852, by Hermann Goldschmidt from the balcony of his apartment in Paris. A preliminary orbit for the asteroid was computed in November–December 1852 by German astronomer Georg Rümker and others. In 1903, it was photographed at opposition by Edward Pickering at Harvard College Observatory. He computed an opposition magnitude of 10.8. There have been two reported
    7.00
    3 votes
    94
    25143 Itokawa

    25143 Itokawa

    • Discovery Organization: Lincoln Near-Earth Asteroid Research
    • Discovery Site: Experimental Test Site
    25143 Itokawa ( /ˌiːtoʊˈkɑːwə/; Japanese: イトカワ [itokawa]) is an Apollo and Mars-crosser asteroid. It was the first asteroid to be the target of a sample return mission, the Japanese space probe Hayabusa. The asteroid was discovered in 1998 by the LINEAR project and was given the provisional designation 1998 SF36. In August 2003, it was officially named after Hideo Itokawa, a Japanese rocket scientist. Itokawa is an S-type asteroid. Radar imaging by Goldstone in 2001 observed an ellipsoid 630 ± 60 m long and 250 ± 30 m wide. The Hayabusa mission confirmed these findings and also suggested that Itokawa may be a contact binary formed by two or more smaller asteroids that have gravitated toward each other and stuck together. The Hayabusa images show a surprising lack of impact craters and a very rough surface studded with boulders, described by the mission team as a 'rubble pile'. Furthermore, the density of the asteroid is too low for it to be made from solid rock. This would mean that Itokawa is not a monolith but rather a ‘rubble pile’ formed from fragments that have cohered over time. Shape from Goldstone and Arecibo Radars (Itokawa). In 2000, it was selected as the target of
    7.00
    3 votes
    95
    29P/Schwassmann-Wachmann

    29P/Schwassmann-Wachmann

    • Discoverer: Friedrich Karl Arnold Schwassmann
    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
    7.00
    3 votes
    96
    8 Flora

    8 Flora

    • Discoverer: John Russell Hind
    • Discovery Site: George Bishop's Observatory, Regent's Park
    8 Flora is a large, bright main-belt asteroid. It is the innermost large asteroid: no asteroid closer to the Sun has a diameter above 25 kilometres or two-elevenths that of Flora itself, and not until the tiny 149 Medusa was discovered was a single asteroid orbiting at a closer mean distance known. It is the seventh brightest asteroid with a mean opposition magnitude of +8.7. Flora can reach a magnitude of +7.9 at a favorable opposition near perihelion, such as occurred in November 2007. Flora may be the residual core of an intensely heated, thermally evolved, and magmatically differentiated planetesimal which was subsequently disrupted. Flora was discovered by J. R. Hind on October 18, 1847. It was his second asteroid discovery after 7 Iris. The name Flora was proposed by John Herschel, from Flora, the Latin goddess of flowers and gardens, wife of Zephyrus (the personification of the West wind), and mother of Spring. The Greek equivalent is Chloris, who has her own asteroid, 410 Chloris, but in Greek Flora is also called Chloris (8 Χλωρίς). Lightcurve analysis indicates that Flora's pole points towards ecliptic coordinates (β, λ) = (16°, 160°) with a 10° uncertainty. This gives an
    7.00
    3 votes
    97
    9969 Braille

    9969 Braille

    • Discoverer: Eleanor F. Helin
    • Discovery Site: Palomar Observatory
    9969 Braille is a small Mars-crossing asteroid that orbits the Sun once every 3.58 years. It was discovered in 1992 by astronomers at Palomar observatory and later named after Louis Braille, the inventor of the writing system for the blind. It was photographed in closeup by the spacecraft Deep Space 1 in 1999, but a malfunction resulted in indistinct images. Discovered on May 27, 1992, by E. F. Helin and K. J. Lawrence working at the Palomar observatory as part of NASA's Planet-Crossing Asteroid Survey, it was given the provisional designation 1992 KD. Later, it was renamed Braille in honour of Louis Braille as suggested by Kennedy Space Center software engineer Kerry Babcock in The Planetary Society's contest titled "Name That Asteroid". Braille has an unusually inclined orbit, and belongs to the somewhat rare class of asteroids known as Mars-crossing asteroids. Simulations of its orbit by scientists of the Deep Space 1 project predict that it will evolve into an Earth-crossing orbit in about 4000 years. Although its closest approach to the Sun is closer than Mars orbit, its highly elliptical orbit takes it almost half-way to Jupiter at its apoapsis, and as such its semi-major
    7.00
    3 votes
    98
    9994 Grotius

    9994 Grotius

    • Discoverer: Tom Gehrels
    • Discovery Site: Palomar Observatory
    9994 Grotius is a main belt asteroid. It orbits the Sun once every 4.15 years. Discovered on September 24, 1960 by C. J. van Houten and I. van Houten-Groeneveld on photographic plates made by T. Gehrels, it was given the provisional designation 4028 P-L. It was later renamed 9994 Grotius, to honour Hugo Grotius.
    7.00
    3 votes
    99
    Comet Hale-Bopp

    Comet Hale-Bopp

    Comet Hale–Bopp (formally designated C/1995 O1) was perhaps the most widely observed comet of the 20th century and one of the brightest seen for many decades. It was visible to the naked eye for a record 18 months, twice as long as the previous record holder, the Great Comet of 1811. Hale–Bopp was discovered on July 23, 1995, at a great distance from the Sun, raising expectations that the comet would brighten considerably by the time it passed close to Earth. Although predicting the brightness of comets with any degree of accuracy is very difficult, Hale–Bopp met or exceeded most predictions when it passed perihelion on April 1, 1997. The comet was dubbed the Great Comet of 1997. The comet was discovered in 1995 by two independent observers, Alan Hale and Thomas Bopp, both in the United States. Hale had spent many hundreds of hours searching for comets without success, and was tracking known comets from his driveway in New Mexico when he chanced upon Hale–Bopp just after midnight. The comet had an apparent magnitude of 10.5 and lay near the globular cluster M70 in the constellation of Sagittarius. Hale first established that there was no other deep-sky object near M70, and then
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    3 votes
    100
    Haumea

    Haumea

    • Discoverer: Michael E. Brown
    Haumea, formal designation 136108 Haumea, is a dwarf planet located beyond Neptune's orbit. Just one-third the mass of Pluto, it was discovered in 2004 by a team headed by Mike Brown of Caltech at the Palomar Observatory in the United States and, in 2005, by a team headed by J. L. Ortiz at the Sierra Nevada Observatory in Spain, though the latter claim has been contested and neither is official. On September 17, 2008, it was designated a dwarf planet by the International Astronomical Union (IAU) and named after Haumea, the Hawaiian goddess of childbirth. Haumea's extreme elongation makes it unique among known dwarf planets. Although its shape has not been directly observed, calculations from its light curve suggest it is an ellipsoid, with its major axis twice as long as its minor. Nonetheless, its gravity is believed sufficient for it to have relaxed into hydrostatic equilibrium, thereby meeting the definition of a dwarf planet. This elongation, along with its unusually rapid rotation, high density, and high albedo (from a surface of crystalline water ice), are thought to be the results of a giant collision, which left Haumea the largest member of a collisional family that
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    3 votes
    101
    4486 Mithra

    4486 Mithra

    • Discoverer: Eric Walter Elst
    • Discovery Site: Siding Spring Observatory
    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.
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    4 votes
    102
    4660 Nereus

    4660 Nereus

    • Discoverer: Eleanor F. Helin
    • Discovery Site: Palomar Observatory
    4660 Nereus ( /ˈnɪəriəs/ NEER-ee-əs; Greek: Νηρέας) is a small (about 0.33 kilometres (0.21 mi)) asteroid. It was discovered by Eleanor F. Helin on February 28, 1982, approximately 1 month after a near pass by the Earth. It is named after Nereus, a Titan in Greek mythology. Nereus is potentially a very important asteroid. It is an Apollo and Mars-crosser, with an orbit that frequently comes very close to Earth, and because of this it is exceptionally accessible to spacecraft. Indeed, because of its small size and close orbit, its delta-V for rendezvous of ~5 km/s is smaller than the Moon's, which is about 6.3 km/s. Nereus makes seven approaches to Earth of less than 5 million km between 1900 and 2100. The closest will be in February 2060, at 1.2 million km. The next close approach is in December 2021, when it will be 3.9 million km away. Its orbital period of 1.82 yr also puts it somewhat near a 2:1 orbital resonance with Earth, which means that an approximately 4-year mission could depart for and return from the asteroid on relatively near passes to the Earth. Nereus was scheduled for visitation by both the private Near Earth Asteroid Prospector (NEAP) probe, and the Japanese
    6.00
    4 votes
    103
    (9961) 1991 XK

    (9961) 1991 XK

    • Discoverer: Hiroshi Kaneda
    • Discovery Site: Kushiro Observatory
    (9961) 1991 XK is a main belt asteroid. It orbits the Sun once every 3.35 years. Discovered by S. Ueda & H. Kaneda on December 4, 1991, it was given the provisional designation "1991 XK".
    8.00
    2 votes
    104
    14 Irene

    14 Irene

    • Discoverer: John Russell Hind
    • Discovery Site: George Bishop's Observatory, Regent's Park
    14 Irene is a large main-belt asteroid. 14 Irene was discovered by J. R. Hind on May 19, 1851, and named after Irēnē, a personification of peace in Greek mythology. She was one of the Horae, daughter of Zeus and Themis. The name was suggested by Sir John Herschel. Hind wrote, The Great Exhibition of the Works of Industry of All Nations in the Crystal Palace of Hyde Park, London, ran from May 1 until October 18, 1851. Hind suggested that the symbol for the asteroid should be "A dove carrying an olive-branch, with a star on its head", but an actual drawing of the symbol was never made before the use of graphical symbols to represent asteroids was dropped entirely. The fairly flat Irenian lightcurves indicate somewhat spherical proportions. There have been four reported stellar occultation events by Irene.
    8.00
    2 votes
    105
    153 Hilda

    153 Hilda

    • Discoverer: Johann Palisa
    • Discovery Site: Pola Observatory
    153 Hilda is a large asteroid in the outer main belt, with a diameter of 170 km. Because it is composed of primitive carbonaceous materials, it has a very dark surface. It was discovered by Johann Palisa on November 2, 1875 from the Austrian Naval Observatory at Pula. The name was chosen by the astronomer Theodor von Oppolzer, who named it after one of his daughters. Hilda gives its name to an asteroid group called the Hilda family (or Hildas for short). It is not a true asteroid family, since the members are not physically related, but rather share similar orbital elements. The Hildas are locked in a 2:3 orbital resonance with Jupiter; since Jupiter takes 11.9 years to orbit the Sun while Hilda takes 7.9 years, Jupiter orbits the Sun twice for every 3 orbits that Hilda completes. There are over 1,100 other objects known to be in a 2:3 resonance with Jupiter. Hilda was observed to occult a star on December 31, 2002, from Japan. It has a very low-amplitude light curve indicating a spherical body or a non-varying albedo.
    8.00
    2 votes
    106
    2685 Masursky

    2685 Masursky

    • Discoverer: Edward L. G. Bowell
    • Discovery Site: Anderson Mesa Station
    The asteroid 2685 Masursky is a main-belt asteroid. It was discovered by Edward (Ted) Bowell in 1981. It was named after Harold Masursky (1923–1990), a planetary geologist at the U.S. Geological Survey, Flagstaff, who worked on numerous space missions. Little was known about Masursky until the Cassini space probe, en route to Jupiter and Saturn, flew past it on 23 January 2000. Since Cassini passed the asteroid at a distance of 1.6 million kilometres (about four times the Earth–Moon distance), the images it returned showed nothing more than a dot. Nevertheless, Cassini was able to determine Masursky's size (about 15–20 km in diameter). Masursky's orbit places it within the Eunomia family of S-type asteroids. Cassini's observations had cast some doubt on its composition, but later ground-based spectroscopy has confirmed its S-type spectrum.
    8.00
    2 votes
    107
    28 Bellona

    28 Bellona

    • Discoverer: Karl Theodor Robert Luther
    • Discovery Site: Düsseldorf-Bilk Observatory
    28 Bellona is a large main-belt asteroid. It was discovered by R. Luther on March 1, 1854, and named after Bellōna, the Roman goddess of war; the name was chosen to mark the beginning of the Crimean War. Bellona has been studied by radar.
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    2 votes
    108
    54509 YORP

    54509 YORP

    54509 YORP (2000 PH5) is an Apollo Near-Earth Object (NEO) discovered on August 3, 2000 by the Lincoln Laboratory Near-Earth Asteroid Research (LINEAR) Team at Socorro. Measurements of the rotation rate of this object provided the first observational evidence of the YORP effect, hence the name of the asteroid. The asteroid's rate of rotation is increasing at the rate of (2.0 ± 0.2) × 10 deg/day which between 2001 and 2005 caused the asteroid to rotate about 250° further than its spin rate in 2001 would have predicted. Simulations of the asteroid suggest that it may reach a rotation period of ~20 seconds near the end of its expected lifetime. The simulations also ruled out the possibility that close encounters with the Earth have been the cause of the increased spin rate.
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    2 votes
    109
    9986 Hirokun

    9986 Hirokun

    • Discoverer: Takeshi Urata
    • Discovery Site: Nachi-Katsuura Observatory
    9986 Hirokun is an S-type main belt asteroid. It orbits the Sun once every 4.12 years. Discovered on July 12, 1996 by Y. Shimizu and T. Urata, it was given the provisional designation 1996 NX. It was later renamed 9986 Hirokun, after the fiancé of T. Urata's daughter.
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    2 votes
    110
    Comet Biela

    Comet Biela

    • Discoverer: Wilhelm Freiherr von 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
    8.00
    2 votes
    111
    Mu Arae d

    Mu Arae d

    • Discoverer: Michel Mayor
    Mu Arae c, also known as HD 160691 c, is an extrasolar planet orbiting around Mu Arae. Its discovery was announced on August 25, 2004. At the time, its minimum mass was reported at just 14 times that of Earth, although later work established a value of 10.5 Earth masses. It orbits very close to Mu Arae, completing one revolution every 9.6 days. The discovery was made with the aid of the High Accuracy Radial Velocity Planet Searcher (HARPS) spectrograph, at the European Southern Observatory's La Silla Observatory in Chile. The data that revealed the presence of this planet was gathered on 8 nights of observations in June 2004. Assuming its true mass is comparable to those of Neptune and Gliese 436 b, 14 Earth masses is theoretically the maximum size for a terrestrial planet. A rocky planet this size could certainly have formed, since Mu Arae has a higher metallicity than our Sun. Also, it is thought to have formed well inside the system's "snow line" at 3.2 AU. However various models of the system's formation have since converged that the planet attracted large amounts of volatiles before its star had cleared out the ice, and that it now has a core of only 6 Earth masses. Its core
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    2 votes
    112
    1217 Maximiliana

    1217 Maximiliana

    • Discoverer: Eugène Joseph Delporte
    • Discovery Site: Observatoire Royal de Belgique
    1217 Maximiliana (1932 EC) is a main-belt asteroid discovered on March 13, 1932 by E. Delporte at Uccle. In 1932 there were 188 minor planets discovered.
    9.00
    1 votes
    113
    20 Massalia

    20 Massalia

    • Discoverer: Annibale de Gasparis
    • Discovery Site: Astronomical Observatory of Capodimonte
    20 Massalia is a large and fairly bright main-belt asteroid. It is also the largest member of the Massalia family of asteroids. Its name is the Greek name for Marseille, the city from which one of the two independent co-discovers, Jean Chacornac, first sighted it. Massalia is an S-type asteroid. It orbits at very low inclination in the intermediate main belt, and is by far the largest asteroid in the Massalia family. The remaining family members are fragments ejected by a cratering event on Massalia. Massalia has an above-average density for S-type asteroids, similar to the density of silicate rocks. As such, it appears to be a solid un-fractured body, a rarity among asteroids of its size. Apart from the few largest bodies over 400 km in diameter, such as 1 Ceres and 4 Vesta, most asteroids appear to have been significantly fractured, or are even rubble piles. In 1998, Bange estimated Massalia to have a mass of 5.2×10 kg assuming that 4 Vesta has 1.35×10 solar mass. The mass of Massalia is dependent on the mass of 4 Vesta and perturbation of 44 Nysa. Lightcurve analysis indicates that Massalia's pole points towards either ecliptic coordinates (β, λ) = (45°, 10°) or (β, λ) = (45°,
    9.00
    1 votes
    114
    253 Mathilde

    253 Mathilde

    • Discoverer: Johann Palisa
    • Discovery Site: Vienna Observatory
    253 Mathilde ( /məˈtɪldə/) is a main-belt asteroid about 50 km in diameter that was discovered by Johann Palisa in 1885. It has a relatively elliptical orbit that requires more than four years to circle the Sun. This asteroid has an unusually slow rate of rotation, requiring 17.4 days to complete a 360° revolution about its axis. It is a primitive C-type asteroid, which means the surface has a high proportion of carbon; giving it a dark surface that reflects only 4% of the light that falls on it. This asteroid was visited by the NEAR Shoemaker spacecraft during June 1997, on its way to asteroid 433 Eros. During the flyby, the spacecraft imaged a hemisphere of the asteroid, revealing many large craters that have gouged out depressions in the surface. Until 21 Lutetia was visited in 2010, it was the largest asteroid to be visited by a spacecraft and the first C-type asteroid to be explored. In 1880, Johann Palisa, the director of the Austrian Naval Observatory, was offered a position as an assistant at the newly completed Vienna Observatory. Although the job represented a demotion for Johann, it gave him access to the new 27-inch (690 mm) refractor, the largest telescope in the world
    9.00
    1 votes
    115
    37 Fides

    37 Fides

    • Discoverer: Karl Theodor Robert Luther
    • Discovery Site: Düsseldorf-Bilk Observatory
    37 Fides ( /ˈfaɪdiːz/ FY-deez) is a large main-belt asteroid. It was discovered by R. Luther on October 5, 1855, and named after Fides, the Roman goddess of loyalty. Fides was the last of the main-belt asteroids to be assigned an iconic symbol.
    9.00
    1 votes
    116
    7166 Kennedy

    7166 Kennedy

    • Discoverer: Edward L. G. Bowell
    • Discovery Site: Lowell Observatory
    7166 Kennedy is an asteroid which was discovered by Edward L. G. Bowell at the Anderson Mesa Station of the Lowell Observatory in Flagstaff, Arizona, on 10 October 1985. Initially designated 1985 TR, it was named on 8 August 1998 in memory of Malcolm Kennedy (1944-1997), Secretary of the Astronomical Society of Glasgow , who died in a road accident in Hungary, 18 November 1997, on a mercy mission carrying aid to eastern Europe. Born and raised in New Zealand, Kennedy became a civil engineer in Scotland. He was an energetic member of the Free Church in Cumbernauld, near Glasgow. As secretary of the ASG, he ensured that meetings ran smoothly, enlivening them with wordplay and puns.
    9.00
    1 votes
    117
    9964 Hideyonoguchi

    9964 Hideyonoguchi

    • Discoverer: Tsutomu Seki
    • Discovery Site: Geisei Observatory
    9964 Hideyonoguchi is a main belt asteroid. It orbits the Sun once every 3.88 years. Discovered on February 13, 1992 by T. Seki, it was given the provisional designation "1992 CF1". It was later renamed "Hideyonoguchi" after Hideyo Noguchi, a bacteriologist who made important advances in medicine working at the Rockefeller Institute for Medical Research.
    9.00
    1 votes
    118
    Great Comet of 1577

    Great Comet of 1577

    The Great Comet of 1577 (official designation: C/1577 V1) was a comet that passed close to Earth during the year 1577 AD. It was viewed by people all over Europe, including famous Danish astronomer Tycho Brahe. From his observations of the comet, Brahe was able to discover that comets and similar objects travel above the Earth's atmosphere. The best-fit using JPL Horizons suggests that the comet is currently about 320 AU from the Sun (based on 24 of Brahe's observations spanning 74 days from 13 November 1577 to 26 January 1578). Tycho Brahe, who is said to have first viewed the comet slightly before sunset on November 13 after having returned from a day of fishing, was the most distinguished observer and documenter of the comet's passing. Sketches found in one of Brahe's notebooks seem to indicate that the comet may have travelled close to Venus. These sketches depict the Earth at the centre of the solar system, with the sun and moon in orbit and the other planets revolving around the Sun, a model that has since been displaced by heliocentricity. Despite these misconceptions on Brahe's part, Brahe left behind thousands of very precise measurements he made of the comet's path, and
    9.00
    1 votes
    119
    PSR B1620-26 b

    PSR B1620-26 b

    • Discoverer: Stephen Thorsett
    PSR B1620-26 b is an extrasolar planet located approximately 12,400 light-years away from Earth in the constellation of Scorpius (the Scorpion). It bears the unofficial nicknames "Methuselah" and "the Genesis planet" due to its extreme age and a few popular sources refer to this object as "PSR B1620-26 c" (see below for discussion). The planet is in a circumbinary orbit around the two stars of PSR B1620-26 (which comprises a pulsar (PSR B1620-26 A) and a white dwarf (WD B1620-26)). The planet is the oldest known extrasolar planet, believed to be about 12.7 billion years old. While the designation PSR B1620-26 b is not used in any scientific papers, the planet is listed in the SIMBAD database as PSR B1620-26 b. Some popular sources use the designation PSR B1620-26 c to refer to the planet, presumably under the logic that since the A and B designations are used for the two stars it orbits, the planetary designations should start at "c". This usage is not supported in the scientific literature, nor does this designation appear in the SIMBAD database. As of November 2008, the only other known circumbinary planets orbit the eclipsing binary HW Virginis, however the discovery paper in
    9.00
    1 votes
    120
    1982 TA

    1982 TA

    • Discoverer: Eleanor F. Helin
    • Discovery Site: Palomar Observatory
    (4197) 1982 TA was discovered on October 11, 1982, by Eleanor F. Helin and Eugene Shoemaker. It is an Apollo, Mars- and Venus-crosser asteroid, only 1.7 km in diameter. In 1996, astronomers at the Goldstone Observatory analysed it using radar delay-Doppler imaging. The resultant images are not very clear, but they show that (4197) 1982 TA has a roughly triangular shape, and a 3-hour rotation period.
    6.67
    3 votes
    121
    21P/Giacobini-Zinner

    21P/Giacobini-Zinner

    • Discoverer: Michel Giacobini
    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.
    6.67
    3 votes
    122
    Gliese 876 d

    Gliese 876 d

    Gliese 876 d is an extrasolar planet approximately 15 light-years away in the constellation of Aquarius (the Water-bearer). The planet was the third planet discovered orbiting the red dwarf star Gliese 876. At the time of its discovery, the planet had the lowest mass of any known extrasolar planet apart from the pulsar planets orbiting PSR B1257+12. Due to this low mass, it can be categorized as a super-Earth. Like the majority of known extrasolar planets, Gliese 876 d was discovered by analysing changes in its star's radial velocity as a result of the planet's gravity. The radial velocity measurements were made by observing the Doppler shift in the star's spectral lines. At the time of discovery, Gliese 876 was known to host two extrasolar planets, designated Gliese 876 b and c, in a 2:1 orbital resonance. After the two planets were taken into account, the radial velocity still showed another period, at around two days. The planet, designated Gliese 876 d, was announced on June 13, 2005 by a team led by Eugenio Rivera and was estimated to have a mass approximately 7.5 times that of Earth. Gliese 876 d is located in an orbit with a semimajor axis of only 0.0208 AU (3.11 million
    6.67
    3 votes
    123
    Great Comet of 1882

    Great Comet of 1882

    The Great Comet of 1882 formally designated C/1882 R1, 1882 II, and 1882b, was a comet which became very bright in September 1882. It was a member of the Kreutz Sungrazers, a family of comets which pass within 1 R☉ of the Sun's photosphere at perihelion. The comet was bright enough to be visible next to the sun in the daytime sky at its perihelion. The comet appeared suddenly in the morning skies of September 1882, and as it was already visible to the naked eye when it became visible it was discovered independently by many people. Reports suggest that it was first seen as early as 1 September 1882, from the Cape of Good Hope as well as the Gulf of Guinea, and over the next few days many observers in the southern hemisphere reported the new comet. The first astronomer to record observations of the comet was W. H. Finlay, the Chief Assistant at the Royal Observatory in Cape Town, South Africa. Finlay's observation on 7 September at 16h GMT was also an independent discovery, and he reported that the comet had an apparent magnitude of about 3, and a tail about a degree in length. The comet brightened rapidly, and within days had become an exceptionally bright object. Her Majesty's
    6.67
    3 votes
    124
    2002 AA29

    2002 AA29

    2002 AA29 (also written 2002 AA29) is a small near-Earth asteroid that was discovered on January 9, 2002 by the LINEAR (Lincoln Near Earth Asteroid Research) automatic sky survey. The diameter of the asteroid is only about 50 to 110 metres (160 to 360 feet). It revolves about the Sun on an almost circular orbit very similar to that of the Earth. This lies for the most part inside the Earth's orbit, which it crosses near the asteroid's furthest point from the Sun, the aphelion. Because of this orbit, the asteroid is classified as Aten type, named after the asteroid (2062) Aten. A further characteristic is that its mean orbital period about the Sun is exactly one sidereal year. This means that it is locked into a relationship with the Earth, since such an orbit is only stable under particular conditions. As yet only a few asteroids of this sort are known, locked into a 1:1 resonance with the Earth. The first was (3753) Cruithne, discovered in 1986. Asteroids that have a 1:1 orbital resonance with a planet are also called co-orbital objects, because they follow the orbit of the planet. The most numerous known co-orbital asteroids are the so-called Trojans, which occupy the L4 and L5
    7.50
    2 votes
    125
    6223 Dahl

    6223 Dahl

    • Discoverer: Antonín Mrkos
    • Discovery Site: Kleť Observatory
    6223 Dahl is an asteroid discovered 3 September 1980 by Antonín Mrkos at the Kleť Observatory in České Budějovice, Czech Republic. It was named in honor of the Welsh author Roald Dahl. See also: List of asteroids.
    7.50
    2 votes
    126
    Comet IRAS-Araki-Alcock

    Comet IRAS-Araki-Alcock

    Comet IRAS–Araki–Alcock (formal designation C/1983 H1, formerly 1983 VII) is a long-period comet that, in 1983, made the closest approach to Earth, about 0.0312 AU (4,670,000 km; 2,900,000 mi), of any comet in 200 years; only Lexell's Comet, in 1770, and 55P/Tempel-Tuttle, in 1366, are thought to have come closer. (The small comet P/1999 J6 (SOHO) passed about 0.01 AU (1,500,000 km; 930,000 mi) from Earth on 1999-Jun-12.) The comet was named after its discoverers – the Infrared Astronomical Satellite and two amateur astronomers, the highly-respected George Alcock of the United Kingdom and Genichi Araki of Japan (both men were schoolteachers by profession, although Alcock was retired). Alcock had made his discovery simply by observing through the window of his home, using binoculars. During the closest approach the comet appeared as a circular cloud about the size of the full moon, having no discernible tail, and shining at a naked eye magnitude of 3-4. It swept across the sky at an incredible speed of some 30 degrees per day. It is a long-period comet, with an orbital period of around 964 years, and is the parent comet of the minor Eta Lyrid meteor shower. This shower's radiant
    7.50
    2 votes
    127
    Pluto

    Pluto

    • Discoverer: Clyde Tombaugh
    • Discovery Organization: Lowell Observatory
    • Discovery Site: Lowell Observatory
    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
    7.50
    2 votes
    128
    9997 COBE

    9997 COBE

    • Discoverer: Tom Gehrels
    • Discovery Site: Palomar Observatory
    9997 COBE is a main belt asteroid. It orbits the Sun once every 4.06 years. Discovered on March 25, 1971 by C. J. van Houten and I. van Houten-Groeneveld in archival data produced by T. Gehrels, it was given the provision designation 1217 T-1. It was later renamed 9997 COBE in honour of the Cosmic Background Explorer.
    4.80
    5 votes
    129
    (33342) 1998 WT24

    (33342) 1998 WT24

    (33342) 1998 WT24 (also written (33342) 1998 WT24) is an Aten asteroid located in Venus' zone of influence that has frequent close encounters with Mercury, Venus, and Earth. It is also one of the best studied potentially hazardous asteroids. (33342) 1998 WT24 was discovered on November 25, 1998, by LINEAR about four months after a particularly close encounter with the planet Mercury (about 0.047 au). At the time of its discovery, astronomers were trying to find the first Apohele asteroid (one that is always closer to the Sun than the Earth). All asteroids known at the time that got closer to the Sun than the Earth also crossed Earth's orbit. Earlier that year, David J. Tholen claimed to have spotted the first Apohele asteroid, which was dubbed 1998 DK36. However, the object was lost without being confirmed. Thus, 1993 DA remained the asteroid with the lowest known aphelion at 1.023 au. When 1998 WT24 was discovered, it was found to have a slightly smaller aphelion than 1993 DA (1.019 au), and was thus the closest thing to an Apohele asteroid known at the time. It lost its smallest aphelion title almost immediately when 1998 XX2 was discovered only a few weeks later (aphelion =
    6.33
    3 votes
    130
    (9966) 1992 ES13

    (9966) 1992 ES13

    • Discovery Site: La Silla Observatory
    (9966) 1992 ES13 is a main belt asteroid. It orbits the Sun once every 3.67 years. Discovered on March 2, 1992 by the Uppsala-ESO Survey of Asteroids and Comets, it was given the provisional designation "1992 ES13".
    6.33
    3 votes
    131
    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
    6.33
    3 votes
    132
    433 Eros

    433 Eros

    • Discoverer: Carl Gustav Witt
    • Discovery Site: Urania Sternwarte
    433 Eros is a near-Earth asteroid (NEA) discovered in 1898, and the first asteroid to be orbited by a probe (in 2000). It is an S-type asteroid approximately 34.4×11.2×11.2 km in size, the second-largest NEA after 1036 Ganymed, and belongs to the Amor group. Eros is a Mars-crosser asteroid, the first known to come within the orbit of Mars. Objects in such an orbit can remain there for only a few hundred million years before the orbit is perturbed by gravitational interactions. Dynamical integrations suggest that Eros may evolve into an Earth-crosser within as short an interval as 2 million years, and has a roughly 50% chance of doing so over a time scale of 10–10 years. It is a potential Earth impactor, comparable in size to the impactor that created the Chicxulub Crater and led to the extinction of the dinosaurs. The NEAR Shoemaker probe visited Eros twice, first with a 1998 flyby, and then by orbiting it in 2000 when it extensively photographed its surface. On February 12, 2001, at the end of its mission, it landed on the asteroid's surface using its maneuvering jets. Eros is named after the Greek god of love, Erōs. It is pronounced  /ˈɪərɒs/ EER-os or sometimes  /ˈɛrɒs/ ERR-os.
    6.33
    3 votes
    133
    Comet Hyakutake

    Comet Hyakutake

    Comet Hyakutake (Japanese pronunciation: [çʲakɯ̥take], formally designated C/1996 B2) is a comet, discovered on 31 January 1996, that passed very close to Earth in March of that year. It was dubbed The Great Comet of 1996; its passage near the Earth was one of the closest cometary approaches of the previous 200 years. Hyakutake appeared very bright in the night sky and was widely seen around the world. The comet temporarily upstaged the much anticipated Comet Hale–Bopp, which was approaching the inner Solar System at the time. Scientific observations of the comet led to several discoveries. Most surprising to cometary scientists was the first discovery of X-ray emission from a comet, believed to have been caused by ionised solar wind particles interacting with neutral atoms in the coma of the comet. The Ulysses spacecraft unexpectedly crossed the comet's tail at a distance of more than 500 million kilometres (3.3 AU or 3×10 mi) from the nucleus, showing that Hyakutake had the longest tail known for a comet. Hyakutake is a long-period comet. Before its most recent passage through the Solar System, its orbital period was about 17,000 years, but the gravitational perturbation of the
    6.33
    3 votes
    134
    (9980) 1995 BQ3

    (9980) 1995 BQ3

    • Discoverer: Takao Kobayashi
    • Discovery Site: Oizumi Observatory
    (9980) 1995 BQ3 is an S-type main belt asteroid. It orbits the Sun once every 4.29 years. Discovered on January 31, 1995 by T. Kobayashi, it was given the provisional designation 1995 BQ3.
    8.00
    1 votes
    135
    10199 Chariklo

    10199 Chariklo

    • Discoverer: James V. Scotti
    • Discovery Organization: Spacewatch
    10199 Chariklo ( /kəˈrɪkloʊ/ kə-RIK-loh, /ˈkærɨkloʊ/ KARR-i-kloh; Greek: Χαρικλώ; provisional designation: 1997 CU26) is the largest known centaur. It orbits the Sun between Saturn and Uranus, grazing Uranus. Chariklo was discovered by James V. Scotti of the Spacewatch program on February 15, 1997. Chariklo is named after the nymph Chariclo (Χαρικλω), the wife of Chiron and the daughter of Apollo. A photometric study in 2001 was unable to find a definite period of rotation. Infrared observations of Chariklo indicate water ice on the surface. Mike Brown's website lists it as a possible dwarf planet with a measured diameter of 258 km. If one knows the absolute magnitude (H) and the albedo of an object, one can estimate the size. But since centaurs are icy comet-like bodies that may outgas, it is very difficult to estimate their albedos. It is also likely that the albedos of some centaurs vary with time and activity levels. With an absolute magnitude (H) of 6.4 and an albedo of 0.06, Chariklo is currently the largest known centaur with an estimated diameter of 258 km. 2060 Chiron (230 km / H=6.5 / albedo=0.07) is likely a close second. The lost centaur 1995 SN55 (H=6.0) may even be
    8.00
    1 votes
    136
    78P/Gehrels

    78P/Gehrels

    • Discoverer: Tom 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.
    8.00
    1 votes
    137
    81P/Wild

    81P/Wild

    • Discoverer: Paul Wild
    Comet 81P/Wild, also known as Wild 2 ( /ˈvɪlt/ VILT), is a comet named after Swiss astronomer Paul Wild, who discovered it in January 6,1978 using a 40-cm Schmidt telescope at Zimmerwald. For most of its 4.5 billion-year lifetime, Wild 2 probably had a more distant and circular orbit. In September 1974, it passed within one million kilometers of the planet Jupiter, whose strong gravitational pull perturbed the comet's orbit and brought it into the inner Solar System. Its orbital period changed from 43 years to about 6 years, and its perihelion is now about 1.59 AU (astronomical unit). NASA's Stardust Mission launched a spacecraft, named Stardust, on February 7, 1999. It flew by Wild 2 on January 2, 2004, and collected particle samples from the comet's coma, which were returned to Earth along with interstellar dust it collected during the journey. 72 close-up shots were taken of Wild 2 by Stardust. They revealed a surface riddled with flat-bottomed depressions, with sheer walls and other features that range from very small to up to 2 kilometres across. These features are believed to be caused by impact craters or gas vents. During Stardust's flyby, at least 10 gas vents were active.
    8.00
    1 votes
    138
    9967 Awanoyumi

    9967 Awanoyumi

    • Discoverer: Kazuro Watanabe
    • Discovery Site: Kitami Observatory
    9967 Awanoyumi is a main belt asteroid. It orbits the Sun once every 4.16 years. Discovered on March 31, 1992 by K. Endate and K. Watanabe, it was given the provisional designation "1992 FV1". It was later renamed Awanoyumi after Yumi Awano, the curator of the Okayama Astronomical Museum.
    8.00
    1 votes
    139
    9993 Kumamoto

    9993 Kumamoto

    • Discoverer: Juro Kobayashi
    • Discovery Site: Kumamoto Civil Astronomical Observatory
    9993 Kumamoto is a main belt asteroid. It orbits the Sun once every 4.04 years. Discovered by J. Kobayashi on November 6, 1997 it was given the provisional designation 1997 VX5. It was later renamed Kumamoto in honour of Kumamoto, the home city of the asteroid's discoverer.
    5.25
    4 votes
    140
    (66391) 1999 KW4

    (66391) 1999 KW4

    (66391) 1999 KW4 (also written (66391) 1999 KW4) is an Aten and Mercury-crosser asteroid discovered by LINEAR in 1999. 1999 KW4 has a moon orbiting it. The moon, designated S/2001 (66391) 1 or '1999 KW4 Beta' is ~360 m in diameter, and orbits 1999 KW4 'Alpha' in 0.758 d (16 hours) at a distance of 2.6 km. The presence of a companion was suggested by photometric observations made June 19–27, 2000 by Petr Pravec and Lenka Šarounová at Observatoř Ondřejov (Ondřejov Observatory) and was confirmed by radar observations from Arecibo Observatory from May 21-23, 2001 by Lance A. M. Benner, Steven J. Ostro, Jon D. Giorgini, Raymond F. Jurgens, Jean-Luc Margot and Michael C. Nolan, announced on May 23, 2001. The shapes of the two bodies and their dynamics are complex. Among other bizarre properties, the equatorial regions of Alpha are very close to breakup: raising a particle a meter above the surface would put it into orbit around the object.
    7.00
    2 votes
    141
    (9976) 1993 TQ

    (9976) 1993 TQ

    • Discoverer: Seiji Shirai
    • Discovery Site: Hidaka Observatory
    (9976) 1993 TQ is a main belt asteroid. It orbits the Sun once every 4.42 years. Discovered on October 9, 1993 by S. Shirai and S. Hayakawa, it was given the provisional designation 1993 TQ.
    7.00
    2 votes
    142
    17121 Fernandonido

    17121 Fernandonido

    • Discovery Organization: Lincoln Near-Earth Asteroid Research
    • Discovery Site: Experimental Test Site
    17121 Fernandonido (1999 JX60) is a main-belt asteroid discovered on May 10, 1999 by the Lincoln Laboratory Near-Earth Asteroid Research Team at Socorro.
    7.00
    2 votes
    143
    18 Melpomene

    18 Melpomene

    • Discoverer: John Russell Hind
    • Discovery Site: George Bishop's Observatory, Regent's Park
    18 Melpomene is a large, bright main-belt asteroid. It is composed of silicates and metals. It was discovered by J. R. Hind on June 24, 1852, and named after Melpomenē, the Muse of tragedy in Greek mythology. Melpomene occulted the star SAO 114159 on December 11, 1978. A possible Melpomenean satellite with a diameter at least 37 km was detected. The satellite candidate received a provisional designation S/1978 (18) 1. Melpomene was observed with the Hubble Space Telescope in 1993. It was able to resolve the asteroid's slightly elongated shape, but no satellites were detected. Melpomene has been studied by radar.
    7.00
    2 votes
    144
    22P/Kopff

    22P/Kopff

    • Discoverer: August Kopff
    Comet Kopff or 22P/Kopff is a periodic comet in our solar system. Discovered on August 23, 1906, it was named after August Kopff who discovered the comet. The comet was missed on its November 1912 return, but was recovered on its June 1919 return. The comet has not been missed since its 1919 return and its last perihelion passage was on May 25, 2009. A close pass by Jupiter in 1939 decreased the perihelion distance and orbital period. The comet 22P/Kopff’s next expected perihelion is October 25, 2015. 22P/Kopff was discovered at Königstuhl Observatory on Heidelberg, Germany. Kopff analyzed photographic plates which he exposed on August 20, 1903 against pre-discovery images of the same region. On August 23, 1903, Kopff concluded it to be a comet with an estimated magnitude of 11. On mid-September 1906, the short-period nature of the comet was recognized by a team headed by Kiel Ebell of the Berkeley Astronomical Department. The comet was missed when it made a return on November 25, 1912 however on June 25, 1919, astronomers recovered the comet. The comet was located less than three days from the predicted position. Over the next several returns to Earth, none were notable until the
    7.00
    2 votes
    145
    26328 Litomyšl

    26328 Litomyšl

    • Discoverer: Miloš Tichý
    • Discovery Site: Kleť Observatory
    26328 Litomyšl is a main belt asteroid with an orbital period of 1258.7751929 days (3.45 years). The asteroid was discovered on November 18, 1998 in Litomyšl, Bohemia, Czech Republic by Miloš Tichý and Zdeněk Moravec.
    7.00
    2 votes
    146
    3362 Khufu

    3362 Khufu

    • Discoverer: R. Scott Dunbar
    • Discovery Site: Palomar Observatory
    3362 Khufu is a near-Earth asteroid. It was discovered by R. Scott Dunbar and Maria A. Barucci at the Palomar Observatory in San Diego County, California, on August 30, 1984. Its provisional designation was 1984 QA. It is named after Khufu, an ancient Egyptian pharaoh. Khufu crosses the orbits of Mars, Earth, and Venus and makes close approaches to Mercury as well. From 1900 to 2100 it drew nearer than 30 Gm (0.2 AU) to Mercury 26, Venus 27, Earth 20, and Mars 11 times.
    7.00
    2 votes
    147
    624 Hektor

    624 Hektor

    • Discoverer: August Kopff
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    624 Hektor is the largest Jupiter Trojan. It was discovered in 1907 by August Kopff. Hektor is a D-type asteroid, dark and reddish in colour. It lies in Jupiter's leading Lagrangian point, L4, called the 'Greek' node after one of the two sides in the legendary Trojan War. Hektor is named after the Trojan hero Hektor and is thus one of two trojan asteroids that is "misplaced" in the wrong camp (the other being 617 Patroclus in the Trojan node). Hektor is one of the most elongated bodies of its size in the Solar System, being 370 × 200 km. It is thought that Hektor might be a contact binary (two asteroids joined by gravitational attraction) like 216 Kleopatra. Hubble Space Telescope observations of Hektor in 1993 did not show an obvious bilobate shape because of a limited angular resolution. On 17 July 2006, the Keck-10m II telescope and its Laser guide star Adaptive Optics (AO) system indicated a bilobate shape for Hektor. Additionally, a 15-km moonlet at 1000 km of Hektor was detected. The satellite's provisional designation is S/2006 (624) 1. Hektor is, so far, the only known binary trojan asteroid in the L4 point and the first trojan with a satellite companion. 617 Patroclus,
    7.00
    2 votes
    148
    9985 Akiko

    9985 Akiko

    • Discoverer: Robert H. McNaught
    • Discovery Site: Yatsuka observatory
    9985 Akiko is a main belt asteroid. It orbits the Sun once every 3.49 years. Discovered by R. H. McNaught and H. Abe on May 12, 1996 it was given the provisional designation 1996 JF. It was later renamed 9985 Akiko after Akiko Yamamoto, a longtime collaborator with H. Abe.
    7.00
    2 votes
    149
    9P/Tempel

    9P/Tempel

    • Discoverer: Ernst Wilhelm Leberecht Tempel
    Tempel 1 (official designation: 9P/Tempel) is a periodic Jupiter-family comet discovered by Wilhelm Tempel in 1867. It completes an orbit of the Sun every 5.5 years. Tempel 1 was the target of the Deep Impact space mission, which photographed a deliberate high-speed impact upon the comet in 2005. It was re-visited by the Stardust spacecraft on February 15, 2011. Tempel 1 was discovered on April 3, 1867, by Wilhelm Tempel, an astronomer working in Marseille. At the time of discovery, it approached perihelion once every 5.68 years (designations 9P/1867 G1 and 1867 II). It was subsequently observed in 1873 (9P/1873 G1, 1873 I, 1873a) and in 1879 (1879 III, 1879b). Photographic attempts during 1898 and 1905 failed to recover the comet, and astronomers surmised that it had disintegrated. In fact, its orbit had changed. Tempel 1's orbit occasionally brings it sufficiently close to Jupiter to be altered, with a consequent change in the comet's orbital period. This occurred in 1881 (closest approach to Jupiter of 0.55 AU), lengthening the orbital period to 6.5 years. Perihelion also changed, increasing by 50 million kilometres, rendering the comet far less visible from Earth. Tempel 1 was
    7.00
    2 votes
    150
    TrES-2 b

    TrES-2 b

    TrES-2b (or Kepler-1b) is an extrasolar planet orbiting the star GSC 03549-02811 located 718 light years away from our solar system. The planet has been identified in 2011 as the darkest known exoplanet, reflecting less than 1% of any light that hits it. The planet's mass and radius indicate that it is a gas giant with a bulk composition similar to that of Jupiter. Unlike Jupiter, but similar to many planets detected around other stars, TrES-2b is located very close to its star, and belongs to the class of planets known as hot Jupiters. This system is within the field of view of the now operational Kepler spacecraft. This planet continues to be studied by other projects and the parameters are being improved continuously. A 2007 study improved stellar and planetary parameters. A 2008 study concluded that the TrES-2 system is a binary star system. This has a significant effect on the values for the stellar and the planetary parameters. TrES-2b was discovered on August 21, 2006 by the Trans-Atlantic Exoplanet Survey (TrES) by detecting the transit of the planet across its parent star using Sleuth (Palomar Observatory, California) and PSST (Lowell Observatory, Arizona), part of the
    7.00
    2 votes
    151
    9968 Serpe

    9968 Serpe

    • Discoverer: Henri Debehogne
    • Discovery Site: La Silla Observatory
    9968 Serpe (provisional designation: 1992 JS2) is a main belt asteroid. It orbits the Sun once every 4.11 years. Discovered on May 4, 1992 by H. Debehogne, it was given the provisional designation "1992 JS2".
    6.00
    3 votes
    152
    XO-1 b

    XO-1 b

    • Discoverer: Ron Bissinger
    XO-1b is an extrasolar planet approximately 560 light-years away in the constellation of Corona Borealis. The planet was discovered orbiting the yellow dwarf star now designated XO-1 in 2006. In 2006, the XO Project an international team of professional and amateur astronomers discovered a Jupiter-sized planet, later named XO-1b, orbiting a Sun-like star. The team, led by Peter McCullough of the Space Telescope Science Institute in Baltimore, had four amateur astronomers hailing from North America and Europe. The XO Project team employed the relatively inexpensive XO Telescope, made from commercial equipment, to search for extrasolar planets. This telescope consists of two 200-millimeter telephoto camera lenses, and resembles binoculars in shape. It stands on the 10,000 foot summit of the Haleakalā volcano on the Hawaiian Island of Maui. From September 2003 to September 2005, the XO Telescope detected tens of thousands of bright stars. In that time, McCullough's team of amateur astronomers studied a few dozen stars they had previously identified as promising candidates for extrasolar planets. The star XO-1, in particular, was marked as a promising candidate in June 2005. The
    5.00
    4 votes
    153
    21711 Wilfredwong

    21711 Wilfredwong

    • Discovery Organization: Lincoln Near-Earth Asteroid Research
    • Discovery Site: Experimental Test Site
    21711 Wilfredwong is an minor planet discovered on September 7, 1999 by MIT Lincoln Laboratory's Near-Earth Asteroid Research (LINEAR) program. It lies in the Ceres belt of the solar system. It was named in honor of Wilfred Wong (born 1988), who was awarded second place in the 2006 Intel International Science and Engineering Fair for his engineering project, Polycaprolactone-Chitosan Nanocomposite Biomaterials for Tissue Engineering and Wound Healing.
    5.67
    3 votes
    154
    (9953) 1991 EB

    (9953) 1991 EB

    • Discoverer: Hiroshi Kaneda
    • Discovery Site: Kushiro Observatory
    (9953) 1991 EB is a main belt asteroid. It orbits the Sun once every 4.25 years. Discovered on March 7, 1991 by Seiji Ueda and Hiroshi Kaneda, it was given the provisional designation "1991 EB".
    6.50
    2 votes
    155
    3200 Phaethon

    3200 Phaethon

    • Discoverer: Simon F. Green
    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
    6.50
    2 votes
    156
    4 Vesta

    4 Vesta

    • Discoverer: Heinrich Wilhelm Matthäus Olbers
    Vesta, formally designated 4 Vesta, is one of the largest asteroids in the Solar System, with a mean diameter of about 525 kilometres (326 mi). It was discovered by Heinrich Wilhelm Olbers on 29 March 1807, and is named after Vesta, the virgin goddess of home and hearth from Roman mythology. Vesta is the second-most-massive asteroid after the dwarf planet Ceres, and comprises an estimated 9% of the mass of the asteroid belt. The less-massive Pallas is slightly larger, making Vesta third in size. Vesta is the last remaining rocky protoplanet (with a differentiated interior) of the kind that formed the terrestrial planets. It lost some 1% of its mass less than a billion years ago in a collision that left an enormous crater occupying much of its southern hemisphere. Debris from this event has fallen to Earth as howardite–eucrite–diogenite (HED) meteorites, a rich source of information about the asteroid. Vesta is the brightest asteroid visible from Earth. Its maximum distance from the Sun is slightly farther than the minimum distance of Ceres from the Sun, though its orbit lies entirely within the Cererian orbit. NASA's Dawn spacecraft entered orbit around Vesta on 16 July 2011 for a
    6.50
    2 votes
    157
    69230 Hermes

    69230 Hermes

    • Discoverer: Karl Wilhelm Reinmuth
    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
    6.50
    2 votes
    158
    704 Interamnia

    704 Interamnia

    • Discoverer: Vincenzo Cerulli
    • Discovery Site: Collurania-Teramo Observatory
    704 Interamnia is a very large asteroid, with an estimated diameter of 350 kilometres. Its mean distance from the Sun is 3.067 (AU). It was discovered on October 2, 1910 by Vincenzo Cerulli, and named after the Latin name for Teramo, Italy, where Cerulli worked. It is probably the fifth-most-massive asteroid after Ceres, Vesta, Pallas, and Hygiea, with a mass estimated to be 1.2% of the mass of the entire asteroid belt. Although Interamnia is the largest asteroid after the "big four", it is a very little-studied body. It is easily the largest of the F-type asteroids, but there exist very few details of its internal composition or shape, and no lightcurve analysis has yet been done to determine the ecliptic coordinates of Interamnia's poles (and hence its axial tilt). Its apparently high bulk density (though subject to much error) suggests an extremely solid body entirely without internal porosity or traces of water. This also strongly suggests that Interamnia is large enough to have fully withstood all the collisions that have occurred in the asteroid belt since the Solar System was formed. Its very dark surface and relatively large distance from the Sun means Interamnia can never
    6.50
    2 votes
    159
    77185 Cherryh

    77185 Cherryh

    77185 Cherryh is a main belt asteroid. Its provisional designation was 2001 FE9. It was discovered on March 20, 2001 at the George Observatory in Needville, Texas by amateur astronomers Don Wells and Alex Cruz of the Fort Bend Astronomy Club (FBAC) Asteroid Discovery Team. The discovery was confirmed the next night by Keith Rivich of the FBAC. The asteroid was named by Wells and Cruz after the award winning American science fiction and fantasy author C. J. Cherryh.
    6.50
    2 votes
    160
    8371 Goven

    8371 Goven

    • Discoverer: Charles P. de Saint-Aignan
    • Discovery Site: Palomar Observatory
    The asteroid 8371 Goven is a Main belt asteroid discovered by Charles de Saint-Aignan at Lowell Observatory, examining films taken at Palomar. The village of Goven in Brittany is the home of the Bernardinis, who were an extraordinary host family for the discoverer during his year-long stay there. Jean-Paul Bernardini served as a navigator in the French Marine during the 1960s, frequently practising the dying art of celestial navigation †. This orbital diagram is courtesy of the JPL Small-Body Database Browser
    6.50
    2 votes
    161
    Comet Arend-Roland

    Comet Arend-Roland

    • Discoverer: Sylvain Julien Victor Arend
    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,
    6.50
    2 votes
    162
    Comet Shoemaker-Levy 9

    Comet Shoemaker-Levy 9

    • Discoverer: Eugene Merle Shoemaker
    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
    6.50
    2 votes
    163
    WASP-1 b

    WASP-1 b

    • Discovery Organization: SuperWASP
    • Discovery Site: South African Astronomical Observatory
    WASP-1b is an extrasolar planet orbiting the star WASP-1 located 1,239 light-years away in the constellation Andromeda. In recognition of the regional support given to the project on La Palma, the discoverers gave the planet the alternative designation Garafia-1. The planet's mass and radius indicate that it is a gas giant with a similar bulk composition to Jupiter. Unlike Jupiter, but similar to many other planets detected around other stars, WASP-1b is located very close to its star, and belongs to the class of planets known as hot Jupiters. WASP-1 b was discovered via the transit method by SuperWASP, for which the star and planet are named. Follow-up radial velocity measurements confirmed the presence of an unseen companion, and allowed for the mass of WASP-1 b to be determined. Media related to WASP-1b at Wikimedia Commons
    6.50
    2 votes
    164
    T Tauri star

    T Tauri star

    • Discoverer: John Russell Hind
    T Tauri stars (TTS) are a class of variable stars named after their prototype – T Tauri. They are found near molecular clouds and identified by their optical variability and strong chromospheric lines. T Tauri stars are pre–main sequence stars – the youngest visible F, G, K, M spectral type stars (
    4.75
    4 votes
    165
    103P/Hartley

    103P/Hartley

    Comet Hartley 2, designated as 103P/Hartley by the Minor Planet Center, is a small periodic comet with an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. Its diameter is estimated to be 1.2 to 1.6 kilometres (0.75 to 0.99 mi). Hartley 2 was the target of a flyby of the Deep Impact spacecraft, as part of the EPOXI mission, on 4 November 2010, which was able to approach within 700 kilometers (430 mi) of Hartley 2 as part of its extended mission. As of November 2010 Hartley 2 is the smallest comet which has been visited. It is the fifth comet visited by spacecraft, and the second comet visited by the Deep Impact spacecraft, which first visited comet Tempel 1 on 4 July 2005. Comet Hartley 2 is a small Jupiter-family comet having an orbital period of 6.46 years. It was discovered by Malcolm Hartley in 1986 at the Schmidt Telescope Unit, Siding Spring Observatory, Australia. It has the perihelion near the Earth's orbit at 1.05 AU from the Sun. The comet passed within 0.12 AU (18,000,000 km; 11,000,000 mi) of Earth on 20 October 2010, only eight days before coming to perihelion (closest
    5.33
    3 votes
    166
    15 Eunomia

    15 Eunomia

    • Discoverer: Annibale de Gasparis
    • Discovery Site: Astronomical Observatory of Capodimonte
    15 Eunomia is a very large asteroid in the inner asteroid belt. It is the largest of the stony (S-type) asteroids, and somewhere between the 8th-to-12th-largest main-belt asteroid overall (uncertainty in diameters causes uncertainty in its ranking). It is the largest Eunomian asteroid, and is estimated to contain 1% of the mass of the asteroid belt. Eunomia was discovered by Annibale de Gasparis on July 29, 1851 and named after Eunomia, one of the Horae (Hours), a personification of order and law in Greek mythology. As the largest S-type asteroid (with 3 Juno being a very close second), Eunomia has attracted a moderate amount of scientific attention. It contains slightly over one percent of the mass of the entire asteroid belt. Eunomia appears to be an elongated but fairly regularly shaped body, with what appear to be four sides of differing curvature and noticeably different average compositions. Its elongation led to the suggestion that Eunomia may be a binary object, but this has been refuted. It is a retrograde rotator with its pole pointing towards ecliptic coordinates (β, λ) = (-65°, 2°) with a 10° uncertainty. This gives an axial tilt of about 165°. Like other true members
    5.33
    3 votes
    167
    1105 Fragaria

    1105 Fragaria

    • Discoverer: Karl Wilhelm Reinmuth
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    1105 Fragaria (1929 AB) is Main-belt asteroid discovered on January 1, 1929, by Karl Wilhelm Reinmuth at the Landessternwarte Heidelberg-Königstuhl in Heidelberg, Germany.
    7.00
    1 votes
    168
    2060 Chiron

    2060 Chiron

    • Discoverer: Charles T. Kowal
    • Discovery Site: Palomar Observatory
    2060 Chiron is a minor planet in the outer Solar System. Discovered in 1977 by Charles T. Kowal (precovery images have been found as far back as 1895), it was the first-known member of a new class of objects now known as centaurs, with an orbit between Saturn and Uranus. Although it was initially called an asteroid and classified as a minor planet, it was later found to exhibit behavior typical of a comet. Today it is classified as both, and accordingly it is also known by the cometary designation 95P/Chiron. Chiron is named after the centaur Chiron in Greek mythology. It should not be confused with the Plutonian moon Charon, discovered the following year, in 1978. Mike Brown lists it as a possible dwarf planet with a measured diameter of 233 km. Chiron was discovered on 18 October 1977 by Charles Kowal from images taken two weeks earlier at Palomar Observatory. It was given the temporary designation of 1977 UB. It was found near aphelion and at the time of discovery it was the most distant known minor planet. Chiron was even claimed as the tenth planet by the press. Chiron was later found on several precovery images, going back to 1895, which allowed its orbit to be accurately
    7.00
    1 votes
    169
    375 Ursula

    375 Ursula

    • Discoverer: Auguste Charlois
    • Discovery Site: Nice Observatory
    375 Ursula is one of the largest asteroids from the asteroid belt. It was discovered by Auguste Charlois on September 18, 1893, in Nice. Observations of an occultation on November 15, 1984, produced six chords indicating an estimated diameter of 216±10 km.
    7.00
    1 votes
    170
    54411 Bobestelle

    54411 Bobestelle

    54411 Bobestelle is an asteroid discovered June 3, 2000 by Peter B. Stetson and David D. Balam at the Canada-France-Hawaii Telescope at Mauna Kea. Its provisional designation was 2000 LH10. Peter Stetson, who discovered the asteroid, is an astronomer with the National Research Council of Canada's Dominion Astrophysical Observatory (DAO). David Balam of the University of Victoria (UVic) confirmed the discovery and performed follow-up observations.
    7.00
    1 votes
    171
    5995 Saint-Aignan

    5995 Saint-Aignan

    • Discoverer: Edward L. G. Bowell
    • Discovery Site: Anderson Mesa Station
    The asteroid 5995 Saint-Aignan is a main belt asteroid discovered by Ted Bowell and named for Charles de Saint-Aignan. Unknown † This orbital diagram is courtesy of the JPL Small-Body Database Browser
    7.00
    1 votes
    172
    9996 ANS

    9996 ANS

    • Discoverer: Tom Gehrels
    • Discovery Site: Palomar Observatory
    9996 ANS is a C-type main belt asteroid. It orbits the Sun once every 4.68 years. Discovered on October 17, 1960 by C. J. van Houten and I. van Houten-Groeneveld on archived photographic plates made by T. Gehrels, it was given the provisional designation 9070 P-L. It was later renamed in honour of the Astronomical Netherlands Satellite, an X-ray and gamma ray telescope located in space.
    7.00
    1 votes
    173
    9998 ISO

    9998 ISO

    • Discoverer: Tom Gehrels
    • Discovery Site: Palomar Observatory
    9998 ISO is a main belt asteroid. It completes one orbit of the Sun every 3.18 years. Discovered on March 25, 1971 by C. J. van Houten & I. van Houten-Groeneveld on archival images taken by T. Gehrels, the body was given a provisional designation of 1293 T-1. It was later renamed 9998 ISO to honour the Infrared Space Observatory.
    7.00
    1 votes
    174
    10 Hygiea

    10 Hygiea

    • Discoverer: Annibale de Gasparis
    • Discovery Site: Astronomical Observatory of Capodimonte
    10 Hygiea is the fourth largest asteroid in the Solar System by volume and mass and is located in the asteroid belt. With somewhat oblong diameters of 350–500 km, and a mass estimated to be 2.9% of the total mass of the belt. It is the largest of the class of dark C-type asteroids with a carbonaceous surface. Despite its size, due to its dark surface and larger-than-average distance from the Sun, it appears very dim when observed from Earth. For this reason several smaller asteroids were observed before Annibale de Gasparis discovered Hygiea on April 12, 1849. At most oppositions, Hygiea has a magnitude that is four orders lower than Vesta's, and observing it will require at least a 100 mm (4-inch) telescope, while at a perihelic opposition, it may be observable with 10x50 binoculars. Hygiea was discovered by Annibale de Gasparis on April 12, 1849, in Naples, Italy. It was the first of his nine asteroid discoveries. The director of the Naples observatory, Ernesto Capocci, named the asteroid. He chose to call it Igea Borbonica ("Bourbon Hygieia") in honor of the ruling family of the Kingdom of the Two Sicilies where Naples was located. However, in 1852, John Russell Hind wrote that
    6.00
    2 votes
    175
    10001 Palermo

    10001 Palermo

    • Discoverer: Lyudmila Chernykh
    • Discovery Site: Crimean Astrophysical Observatory
    10001 Palermo is a main-belt asteroid. Discovered on October 8, 1969, it was named "Palermo" after Palermo, the capital of Sicily where Giuseppe Piazzi made the first discovery of an asteroid, 1 Ceres. The naming was made in January 2001 to honour the discovery of Ceres, as that was the 200th anniversary of that discovery. The asteroid is about six kilometers in radius, although it may be irregularly shaped. It orbits the Sun every 3.67 years.
    6.00
    2 votes
    176
    2008 TC3

    2008 TC3

    • Discovery Organization: Catalina Sky Survey
    2008 TC3 (Catalina Sky Survey temporary designation 8TA9D69) was a meteoroid 2 to 5 meters (7 to 16 ft) in diameter and weighing 80 tonnes, that entered Earth's atmosphere on October 7, 2008, at 02:46 UTC (05:46 local time). The meteoroid was notable as the first such body to be observed and tracked prior to reaching Earth. It exploded an estimated 37 kilometers (23 mi) above the Nubian Desert in Sudan. A search of the impact zone that began on December 2008 turned up 10.5 kilograms (23 lb) of meteorites in 600 fragments, which are surviving pieces of the meteoroid. The meteorites are of a rare type known as ureilites, which contain, among other minerals, nanodiamonds. The meteoroid was discovered by Richard A. Kowalski at the Catalina Sky Survey (CSS) 1.5-meter telescope at Mount Lemmon, north of Tucson, Arizona, USA, on October 6, 06:39 UTC, about 20 hours before the impact. The meteoroid was notable as the first such body to be observed and tracked prior to reaching Earth. The process of detecting and tracking a near-Earth object, an effort sometimes referred to as Spaceguard, was put to the test. In total, 586 astrometric and almost as many photometric observations were
    6.00
    2 votes
    177
    24P/Schaumasse

    24P/Schaumasse

    • Discoverer: Alexandre Schaumasse
    Comet Schaumasse is a periodic comet discovered by Alexandre Schaumasse (Nice, France) on December 1, 1911 as 12th magnitude. By the end of 1912 it was recognised as a short period comet estimated to return in 7.1 years, later recalculated as 8 years. The 1919 return was recovered by Gaston Fayet (Paris, France) as magnitude 10.5. The 1927 approach was magnitude 12, but the comet was missed on the 1935 approach. In 1937 it passed close to Jupiter which increased its orbital period slightly. The comet was missed in 1968 and 1976. It was speculated that the increase in brightness in 1952 indicated a problem that led to it vanishing. In 1984, Elizabeth Roemer (Steward Observatory, Arizona, USA) found an image on photographs from 1976. The approach later that year, observed by James B. Gibson (Palomar Observatory, California, USA) and orbital calculations by Brian G. Marsden, confirmed the 1976 image was Comet Schaumasse. The comet has not been observed since 2001. The comet was not observed during the 2009 unfavorable apparition since the perihelion passage occurred when the comet was on the far side of the Sun. It will pass about 0.6 AU (90,000,000 km; 56,000,000 mi) from the Earth
    6.00
    2 votes
    178
    52 Europa

    52 Europa

    • Discoverer: Hermann Mayer Salomon Goldschmidt
    • Discovery Site: Paris Observatory
    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
    6.00
    2 votes
    179
    65 Cybele

    65 Cybele

    • Discoverer: Ernst Wilhelm Leberecht Tempel
    • Discovery Site: Marseille Observatory
    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
    6.00
    2 votes
    180
    9973 Szpilman

    9973 Szpilman

    • Discoverer: Eric Walter Elst
    • Discovery Site: La Silla Observatory
    9973 Szpilman (pronounced: Shpilman) is a main belt asteroid. It orbits the Sun once every 4.03 years. Discovered on July 12, 1993 by E. W. Elst working at the European Southern Observatory, it was given the provisional designation 1993 NB2. It was later renamed "Szpilman" after Wladyslaw Szpilman, a Polish pianist.
    6.00
    2 votes
    181
    Gliese 436 b

    Gliese 436 b

    • Discoverer: Geoffrey Marcy
    Gliese 436 b ( /ˈɡliːzə/) is a Neptune-sized extrasolar planet orbiting the red dwarf star Gliese 436. It was among the smallest known transiting planets in mass and radius until the much smaller Kepler discoveries started coming in 2010. Gliese 436 b was discovered in August 2004 by R. Paul Butler and Geoffrey Marcy of the Carnegie Institute of Washington and University of California, Berkeley, respectively, using the radial velocity method. Together with 55 Cancri e, it was then the first of a new class of planets with a minimum mass (M sini) similar to Neptune. The planet was recorded to transit its star by an automatic process at NMSU on January 11, 2005, but this event went unheeded at the time. In 2007, Gillon led a team which observed the transit, grazing the stellar disc relative to Earth. Transit observations led to the determination of Gliese 436 b's exact mass and radius, both of which are very similar to Neptune. Gliese 436 b then became the smallest known transiting extrasolar planet. The planet is about 4000 km larger in diameter than Uranus and 5000 km larger than Neptune and a bit more massive. Gliese 436b (also known as GJ 436b) orbits its star at a distance of
    6.00
    2 votes
    182
    3552 Don Quixote

    3552 Don Quixote

    • Discoverer: Paul Wild
    • Discovery Site: Zimmerwald Observatory
    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.
    5.00
    3 votes
    183
    8379 Straczynski

    8379 Straczynski

    • Discovery Organization: Spacewatch
    • Discovery Site: Kitt Peak National Observatory
    8379 Straczynski (provisional designation 1992 SW10) is an asteroid discovered on September 27, 1992 at the Kitt Peak National Observatory by the Spacewatch project. It was named in honour of science fiction writer J. Michael Straczynski, creator of the television series Babylon 5.
    5.00
    3 votes
    184
    9957 Raffaellosanti

    9957 Raffaellosanti

    • Discoverer: Freimut Börngen
    • Discovery Site: Karl Schwarzschild Observatory
    9957 Raffaellosanti is a main belt asteroid. It orbits the Sun once every 3.46 years. Discovered on October 6, 1991 by F. Börngen, it was given the provisional designation "1991 TO13". It was later renamed "Raffaellosanti" after Raffaello Sanzio, a master of the Italian Renaissance.
    5.00
    3 votes
    185
    Asteroid belt

    Asteroid belt

    The asteroid belt is the region of the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt because there are other asteroids in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids, Ceres, Vesta, Pallas, and Hygiea. These have mean diameters of more than 400 km, while Ceres, the asteroid belt's only dwarf planet, is about 950 km in diameter. The remaining bodies range down to the size of a dust particle. The asteroid material is so thinly distributed that numerous unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, and these can form an asteroid family whose members have similar orbital characteristics and compositions. Collisions also produce a fine dust that forms a major component of the zodiacal light. Individual asteroids within the asteroid belt are categorized by their spectra, with most falling into three basic groups: carbonaceous (C-type),
    5.00
    3 votes
    186
    Comet West

    Comet West

    • Discoverer: Richard Martin 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
    5.00
    3 votes
    187
    11714 Mikebrown

    11714 Mikebrown

    • Discovery Organization: Lowell Observatory Near-Earth-Object Search
    • Discovery Site: Anderson Mesa Station
    11714 Mikebrown (1998 HQ51) is a main-belt asteroid discovered by Lowell Observatory. It is named after the astronomer Michael E. Brown. Mikebrown is unusually eccentric and not very bright. With an absolute magnitude (H) of only 13.9, it is likely less than 10km in diameter. Astronomers have not noticed any outbursts by Mikebrown. On May 15th, 2012, Mikebrown will come within about 14.8 Gm (0.099 AU) of Xenia.
    5.50
    2 votes
    188
    47 Ursae Majoris b

    47 Ursae Majoris b

    • Discoverer: Geoffrey Marcy
    47 Ursae Majoris b (sometimes abbreviated 47 Uma b) is an extrasolar planet approximately 46 light-years from Earth in the constellation of Ursa Major. The planet was discovered located in a long-period orbit around the star 47 Ursae Majoris in January 1996 and as of 2011 is the innermost of three known planets in its planetary system. It has a mass at least 2.53 times that of Jupiter. Like the majority of known extrasolar planets, 47 Ursae Majoris b was discovered by detecting the changes in its star's radial velocity as the planet's gravity pulls the star around. This was achieved by observing the Doppler shift of the spectrum of 47 Ursae Majoris. After the discovery of the first extrasolar planet around a Sun-like star, 51 Pegasi b, astronomers Geoffrey Marcy and R. Paul Butler searched through their observational data for signs of extrasolar planets and soon discovered two: 47 Ursae Majoris b and 70 Virginis b. The discovery of 47 Ursae Majoris b was announced in 1996. 47 Ursae Majoris b orbits at a distance of 2.10 AU from its star, taking 1,078 days or 2.95 years to complete a revolution. It was the first long-period planet around a main sequence star to be discovered. Unlike
    5.50
    2 votes
    189
    Hyperion

    Hyperion

    • Discoverer: William Cranch Bond
    Hyperion ( /haɪˈpɪəriən/; Greek: Ὑπερίων), also known as Saturn VII, is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. It is distinguished by its irregular shape, its chaotic rotation, and its unexplained sponge-like appearance. It was the first non-round moon to be discovered. The moon is named after Hyperion, the Titan god of watchfulness and observation – the elder brother of Cronus, the Greek equivalent of Saturn – in Greek Mythology. It is also designated Saturn VII. The adjectival form of the name is Hyperionian. Hyperion's discovery came shortly after John Herschel had suggested names for the seven previously-known satellites of Saturn in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope. William Lassell, who saw Hyperion two days after William Bond, had already endorsed Herschel's naming scheme and suggested the name Hyperion in accordance with it. He also beat Bond to publication. Hyperion is one of the largest bodies known to be highly irregularly shaped (non-ellipsoidal; i.e. not in hydrostatic equilibrium) in the Solar System. The only larger moon known to be irregular in shape
    5.50
    2 votes
    190
    U Geminorum

    U Geminorum

    • Discoverer: John Russell Hind
    U Geminorum (U Gem), in the constellation Gemini, is an archetypal example of a dwarf nova. The binary star system consists of a white dwarf closely orbiting a red dwarf. Roughly every 100 days it undergoes an outburst that greatly increases its brightness. Discovered by J.R. Hind in 1855 during one of its outbursts, it has been continuously observed since. The U Geminorum binary has a very short orbital period of 4 hours and 11 minutes; this orbit alone makes the system variable, as the components transit and eclipse each other with each revolution. Normally, the combined apparent magnitude varies between 14.0 and 15.1; during an outburst however, the star can brighten a hundredfold, to 9th magnitude. Though the average interval is 100 days, the period is in fact highly irregular, varying from as little as 62 days to as long as 257. As is the case with dwarf novae, the outbursts are theorized results of a periodic surge of influx from the white dwarf's accretion disk, caused by instability in the disk itself. Distance estimates for U Geminorum have varied from 52 parsecs (170 light-years) to 112 parsecs (370 light-years), with a best estimate of 82 parsecs (270 light-years).
    5.50
    2 votes
    191
    (101955) 1999 RQ36

    (101955) 1999 RQ36

    (101955) 1999 RQ36 is an Apollo asteroid discovered by LINEAR on September 11, 1999. The asteroid is the planned target of the OSIRIS-REx mission which will return samples to Earth for further study. It is a potential Earth impactor and is listed on the Sentry Risk Table. It has a mean diameter of approximately 493 meters and has been observed extensively with the Arecibo Observatory Planetary Radar and the Goldstone Deep Space Network. A recent dynamical study by Andrea Milani and collaborators has located a series of eight potential Earth impacts between 2169 and 2199. The cumulative probability of impact is dependent on poorly known physical properties of the object, but is not higher than 0.07% for all eight encounters. To accurately assess 1999 RQ36's probability of Earth impact will require a detailed shape model of the asteroid and additional observations (either from the ground or from spacecraft visiting the object) to determine the magnitude of the Yarkovsky acceleration. Separately, 1999 RQ36 has been considered many times as the target of spacecraft missions, including OSIRIS-REx, due to the low Δv required to reach it from Earth orbit. NASA announced on May 25, 2011,
    6.00
    1 votes
    192
    (9990) 1997 SO17

    (9990) 1997 SO17

    • Discoverer: Tomimaru Okuni
    • Discovery Site: Nanyo Observatory
    (9990) 1997 SO17 is a main belt asteroid. It orbits the Sun once every 4.76 years. It was discovered by Tomimaru Okuni on September 30, 1997 and given the provisional designation 1997 SO17.
    6.00
    1 votes
    193
    1620 Geographos

    1620 Geographos

    • Discoverer: Albert George Wilson
    • Discovery Site: Palomar Observatory
    The asteroid 1620 Geographos ( /dʒiːoʊˈɡræfɒs/) was discovered on September 14, 1951 at the Palomar Observatory by Albert George Wilson and Rudolph Minkowski. It was originally given the provisional designation 1951 RA. Its name, a Greek word meaning "geographer" (geo– 'Earth' + graphos 'drawer/writer'), was chosen to honour geographers and the National Geographic Society. Geographos is a Mars-crosser asteroid and a near-Earth object belonging to the Apollos. In 1994, during the asteroid's closest approach to Earth in two centuries at 5.0 Gm-which will not be bettered until 2586- a radar study of it was conducted by the Deep Space Network at Goldstone, California. The resultant images show Geographos to be the most elongated object in the solar system; it measures 5.1×1.8 km. Geographos is an S-type asteroid, meaning that it is highly reflective and composed of nickel-iron mixed with iron- and magnesium-silicates. Geographos was to be explored by the U.S.'s Clementine mission; however, a malfunctioning thruster ended the mission before it could approach the asteroid.
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    194
    96P/Machholz

    96P/Machholz

    • Discoverer: Donald Machholz
    Comet 96P/Machholz or 96P/Machholz 1 is a short-period comet discovered on May 12, 1986 by amateur astronomer Donald Machholz on Loma Prieta peak, in central California using 130 millimetres (5.1 in) binoculars. On June 6, 1986, comet 96P/Machholz passed 0.40373 AU (60,397,000 km; 37,529,000 mi) from the Earth. Comet 96P/Machholz last came to perihelion on July 14, 2012, and will next come to perihelion on October 27, 2017. 96P/Machholz has an estimated radius of around 3.2km. Machholz 1 is unusual among comets in several respects. Its highly eccentric 5.2 year orbit has the smallest perihelion distance known among numbered/regular short-period comets, bringing it considerably closer to the Sun than the orbit of Mercury. It is also the only known short-period comet with both high orbital inclination and high eccentricity. In 2007, Machholz 1 was found to be both carbon-depleted and cyanogen-depleted, a chemical composition nearly unique among comets with known compositions. The chemical composition implies a different and possible extrasolar origin. The orbit of Machholz 1 corresponds to the Arietids and the Marsden and Kracht Comet groups. Its Tisserand parameter with respect to
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    195
    Comet Kohoutek

    Comet Kohoutek

    • Discoverer: Luboš 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
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    196
    Transit of Venus

    Transit of Venus

    • Discoverer: Jeremiah Horrocks
    A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and Earth (or another planet), becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus can be seen from Earth as a small black disk moving across the face of the Sun. The duration of such transits is usually measured in hours (the transit of 2012 lasted 6 hours and 40 minutes). A transit is similar to a solar eclipse by the Moon. While the diameter of Venus is more than 3 times that of the Moon, Venus appears smaller, and travels more slowly across the face of the Sun, because it is much farther away from Earth. Transits of Venus are among the rarest of predictable astronomical phenomena. They occur in a pattern that generally repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The periodicity is a reflection of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 commensurabilities. The last transit of Venus was on 5 and 6 June 2012, and was the last Venus transit of the 21st century; the prior transit took place on 8 June 2004. The
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    197
    (136617) 1994 CC

    (136617) 1994 CC

    • Discovery Organization: Spacewatch
    (136617) 1994 CC is a near-Earth asteroid that was discovered on February 3, 1994, by Spacewatch's Jim Scotti. In June 2009 it was shown to be a triple system, i.e. the main body has two satellites; only about one percent (1%) of near-Earth asteroids observed by a radar are found to be triple systems such as this one. A team of NASA's Jet Propulsion Laboratory (JPL) (Pasadena, California) scientists led by Marina Brozovic and Lance Benner, made the discovery using radar imaging at NASA's Goldstone Solar System Radar on June 12 and June 14, 2009. They showed that the near-Earth asteroid 1994 CC is a triple system, which encountered Earth within 2.52 million kilometers on June 10, 2009. This relatively close approach to Earth made the discovery possible, as before the approach, scientists knew very little about this asteroid. In fact, 1994 CC is only the second triple system known in the near-Earth objects population. 1994 CC consists of a central object about 700 meters in diameter that has two moons revolving around it. Scientists' preliminary analysis of the system suggests that the moons are at least 50 meters in diameter. In a similar study, the radar observations at Arecibo
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    198
    (29075) 1950 DA

    (29075) 1950 DA

    • Discoverer: Carl A. Wirtanen
    • Discovery Site: Lick Observatory
    (29075) 1950 DA is a near-Earth asteroid. It is notable for having the highest known probability of impacting Earth (between 0 and 0.33%). It has the highest Palermo rating with a value of 0.17 for a possible collision in the year 2880. For a brief period in late December 2004, asteroid 99942 Apophis held the record for Palermo scale values, with a value of 1.10. 1950 DA was first discovered on February 23, 1950, by Carl A. Wirtanen at Lick Observatory. It was observed for seventeen days and then lost because the short observation arc resulted in large uncertainties in Wirtanen's orbital solution. On 31 December 2000, it was recovered as 2000 YK66 and 2 hours later was recognized as 1950 DA. On March 5, 2001, 1950 DA made a close approach to the Earth of 0.0520726 AU (7,789,950 km; 4,840,450 mi). It was studied by radar at the Goldstone and Arecibo observatories from March 3 to 7 2001. The studies showed that the asteroid has a mean diameter of 1.1–1.4 km (3,600-4,600 ft). Optical lightcurve analysis by Lenka Sarounova and Petr Pravec shows that its rotation period is 2.1216 ± 0.0001 hours. Due to its short rotation period and high radar albedo, 1950 DA is thought to be fairly
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    199
    (9977) 1994 AH

    (9977) 1994 AH

    • Discoverer: Takao Kobayashi
    • Discovery Site: Oizumi Observatory
    (9977) 1994 AH is a C-type main belt asteroid. It orbits the Sun once every 5.03 years. Discovered by T. Kobayashi on January 2, 1994, it was given the provisional designation 1994 AH.
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    200
    5 Astraea

    5 Astraea

    • Discoverer: Karl Ludwig Hencke
    5 Astraea is a large main-belt asteroid. Its surface is highly reflective (bright) and its composition is probably a mixture of nickel-iron with magnesium- and iron-silicates. Astraea was the fifth asteroid discovered, on December 8, 1845, by K. L. Hencke and named for Astræa, a goddess of justice named after the stars. It was his first of two asteroid discoveries. The second was 6 Hebe. An amateur astronomer and post office employee, Hencke was looking for 4 Vesta when he stumbled on Astraea. The King of Prussia awarded him an annual pension of 1,200 marks for the discovery. Photometry indicates prograde rotation, that the north pole points in the direction of right ascension 9 h 52 min, declination 73° with a 5° uncertainty. This gives an axial tilt of about 33°. Astraea is physically unremarkable but notable mainly because for 38 years (after the discovery of Vesta in 1807) it had been thought that there were only four asteroids. In terms of maximum brightness, it is indeed only the seventeenth brightest main-belt asteroid, being fainter than 192 Nausikaa and even, at rare near-perihelion oppositions, the highly eccentric carbonaceous 324 Bamberga. It will be at magnitude +8.7
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    201
    773 Irmintraud

    773 Irmintraud

    • Discoverer: Franz Kaiser
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    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
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    202
    118P/Shoemaker-Levy

    118P/Shoemaker-Levy

    • Discoverer: Eugene Merle Shoemaker
    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.
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    203
    9951 Tyrannosaurus

    9951 Tyrannosaurus

    • Discoverer: Eric Walter Elst
    • Discovery Site: La Silla Observatory
    9951 Tyrannosaurus is an S-type main belt asteroid. It orbits the Sun once every 3.78 years. Discovered on November 15, 1990 by E. W. Elst it was given the provisional designation "1990 VK5". On November 21, 2002 it was renamed "Tyrannosaurus" after Tyrannosaurus, a genus of large carnivorous dinosaur of the late Cretaceous.
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    2 votes
    204
    9962 Pfau

    9962 Pfau

    • Discoverer: Freimut Börngen
    • Discovery Site: Karl Schwarzschild Observatory
    9962 Pfau is a main belt asteroid. It orbits the Sun once every 3.68 years. Discovered on December 28, 1991 by F. Borngen, it was given the provisional designation "1991 YL1". It was later renamed "Pfau" after Werner Pfau, a former director of the Jena University Observatory and former chairman of the Astronomische Gesellschaft.
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    205
    99942 Apophis

    99942 Apophis

    • Discoverer: Roy A. Tucker
    99942 Apophis ( /əˈpɒfɪs/, previously known by its provisional designation 2004 MN4) is a near-Earth asteroid that caused a brief period of concern in December 2004 because initial observations indicated a small probability (up to 2.7%) that it would strike the Earth in 2029. Additional observations provided improved predictions that eliminated the possibility of an impact on Earth or the Moon in 2029. However, a possibility remained that during the 2029 close encounter with Earth, Apophis would pass through a gravitational keyhole, a precise region in space no more than about a half-mile wide, that would set up a future impact on April 13, 2036. This possibility kept the asteroid at Level 1 on the Torino impact hazard scale until August 2006, when the probability that Apophis will pass through the keyhole was determined to be very small. Apophis broke the record for the highest level on the Torino Scale, being, for only a short time, a level 4, before it was lowered. Its diameter is approximately 270 meters (885 ft). As of October 7, 2009 (2009 -10-07), the probability of an April 13, 2036 impact is considered to be 1 in 250,000. Of objects not recently observed, there are 7
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    206
    Coma Berenices

    Coma Berenices

    Coma Berenices is a traditional asterism that has since been defined as one of the 88 modern constellations. It is located near Leo, to which it formerly belonged, and accommodates the North Galactic Pole. Its name means "Berenice's Hair" (in Greek, via Latin), and refers to the legend of Queen Berenice II of Egypt, who sacrificed her long hair. Coma Berenices is one of the few constellations to owe its name to a historical figure, in this case Queen Berenice II of Egypt, wife of Ptolemy III Euergetes (fl. 246 BC–221 BC), the king under whom Alexandria became an important cultural center. In 243 BC, during the Third Syrian War, Ptolemy undertook a dangerous expedition against the Seleucids, who had murdered his sister. His newlywed bride, Berenice, swore to the goddess Aphrodite to sacrifice her long, blonde hair, of which she was extremely proud, if her husband returned safely. He did, so she cut her hair and placed it in the goddess's temple. By the next morning the hair had disappeared. To appease the furious king the court astronomer, Conon, announced that the offering had so pleased the goddess that she had placed it in the sky. He indicated a cluster of stars that have since
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    207
    (9989) 1997 SG16

    (9989) 1997 SG16

    • Discoverer: Nobuhiro Kawasato
    • Discovery Site: Uenohara Observatory
    (9989) 1997 SG16 is a main belt asteroid. It orbits the Sun once every 4.82 years. Discovered by Nobuhiro Kawasato on September 27, 1997, it was given the provisional designation 1997 SG16.
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    208
    159743 Kluk

    159743 Kluk

    159743 Kluk is an asteroid. It was discovered by Jana Tichá and Miloš Tichý at the Kleť Observatory near České Budějovice, Czech Republic, on March 23, 2003. Its provisional designation was 2003 FW1. It is named after a granulite hill near Mount Kleť.
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    209
    4179 Toutatis

    4179 Toutatis

    • Discoverer: Christian Pollas
    • Discovery Site: Centre de recherches en géodynamique et astrométrie
    4179 Toutatis/1989 AC ( /tuːˈtɑːtɨs/ too-TAH-tis) is an Apollo, Alinda, and Mars-crosser asteroid with a chaotic orbit produced by a 3:1 resonance with the planet Jupiter, a 1:4 resonance with the planet Earth, and frequent close approaches to the terrestrial planets, including Earth. It is listed as a potentially hazardous object, although the odds of a collision with the Earth are very small. 4179 Toutatis was first sighted on February 10, 1934, as object 1934 CT, and then promptly lost. It remained a lost asteroid for several decades until it was recovered on January 4, 1989, by Christian Pollas, and was named after the Celtic god Toutatis/Teutates—known to popular culture as the God that the cartoon character Astérix's chief Vitalstatistix evokes so that the sky may never fall on his head. The spectral properties suggest that this is an S-type, or stony asteroid, consisting primarily of silicates. It has a moderately bright Bond albedo of 0.13. Radar imagery shows that Toutatis is a highly irregular body consisting of two distinct "lobes", with maximum widths of about 4.6 km and 2.4 km respectively. It is hypothesized that Toutatis formed from two originally separate bodies
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    210
    51 Pegasi b

    51 Pegasi b

    • Discoverer: Michel Mayor
    51 Pegasi b (abbreviated 51 Peg b), sometimes though unofficially named Bellerophon, is an extrasolar planet approximately 50 light-years away in the constellation of Pegasus. 51 Pegasi b was the first planet to be discovered orbiting a main sequence star, the Sun-like 51 Pegasi (the first exoplanets at all were discovered in 1992 by Aleksander Wolszczan around pulsar PSR 1257), and marked a breakthrough in astronomical research. It is the prototype for a class of planets called hot Jupiters. The name 51 Pegasi b is the official astronomical name of the planet. As with all extrasolar planets, the 'b' is used to indicate that this planet was the first discovered orbiting its parent star. Further undiscovered planets of 51 Pegasi would be designated c, d, e, f, and so on. All extrasolar planets have lowercase letters to differentiate from companion stars in the system (which are designated with an uppercase letter). Though not officially recognized, 51 Pegasi b is sometimes referred to as "Bellerophon." This name comes from the Greek hero Bellerophon, who tamed Pegasus (the Winged Horse). This has direct relations with the constellation in which lies the planet (Pegasus). This name
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    211
    55 Cancri e

    55 Cancri e

    55 Cancri e (abbreviated 55 Cnc e) is an extrasolar planet orbiting the Sun-like star 55 Cancri A. Its mass is about 7.8 Earth masses and its diameter is about twice that of Earth's, thus classifying it as the first Super-Earth discovered around a main sequence star, predating Gliese 876 d by a year. It takes less than 18 hours to complete an orbit and is the innermost known planet in its planetary system. 55 Cancri e was discovered on August 30, 2004. However, until the 2010 observations and recalculations, this planet had been thought to take about 2.8 days to orbit the star. In October 2012, it was announced that 55 Cancri e could be a carbon planet. Like the majority of known extrasolar planets (found previous to the Kepler mission), 55 Cancri e was discovered by detecting variations in its star's radial velocity. This was achieved by making sensitive measurements of the Doppler shift of the spectrum of 55 Cancri A. At the time of its discovery, three other planets were known orbiting the star. After accounting for these planets, a signal at around 2.8 days remained, which could be explained by a planet of at least 14.2 Earth masses in a very close orbit. The same measurements
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    212
    73P/Schwassmann-Wachmann

    73P/Schwassmann-Wachmann

    • Discoverer: Arno Arthur 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
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    213
    Comet Donati

    Comet Donati

    • Discoverer: Giovanni Battista 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.
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    214
    Great Comet of 1744

    Great Comet of 1744

    The Great Comet of 1744, whose official designation is C/1743 X1, and which is also known as Comet de Chéseaux or Comet Klinkenberg-Chéseaux, was a spectacular comet that was observed during 1743 and 1744. It was discovered independently in late November 1743 by Jan de Munck, in the second week of December by Dirk Klinkenberg, and, four days later, by Jean-Philippe de Chéseaux. It became visible with the naked eye for several months in 1744 and displayed dramatic and unusual effects in the sky. Its absolute magnitude — or intrinsic brightness — of 0.5 was the sixth highest in recorded history. Its apparent magnitude may have reached as high as -7, leading it to be classified among what are called the "Great Comets". This comet is noted especially for developing a 'fan' of six tails after reaching its perihelion. The comet was discovered on November 29, 1743, by Jan de Munck at Middelburg, and was independently sighted on December 9, 1743 by Klinkenberg at Haarlem, and by Chéseaux from the observatory at Lausanne on December 13. Chéseaux said it lacked a tail and resembled a nebulous star of the third magnitude; he measured the coma as five minutes across. The comet brightened
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    215
    Messier 81

    Messier 81

    • Discoverer: Johann Elert Bode
    Messier 81 (also known as NGC 3031 or Bode's Galaxy) is a spiral galaxy about 12 million light-years away in the constellation Ursa Major. Due to its proximity to Earth, large size and active galactic nucleus (which harbors a 70 million M☉ supermassive black hole), Messier 81 has been studied extensively by professional astronomers. The galaxy's large size and relatively high brightness also make it a popular target for amateur astronomers. Messier 81 was first discovered by Johann Elert Bode in 1774. Consequently, the galaxy is sometimes referred to as "Bode's Galaxy". In 1779, Pierre Méchain and Charles Messier reidentified Bode's object, which was subsequently listed in the Messier Catalogue. Most of the emission at infrared wavelengths originates from interstellar dust. This interstellar dust is found primarily within the galaxy's spiral arms, and it has been shown to be associated with star formation regions. The general explanation is that the hot, short-lived blue stars that are found within star formation regions are very effective at heating the dust and hence enhancing the infrared dust emission from these regions. Only one supernova has been detected in Messier 81. The
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    216
    C/1861 J1

    C/1861 J1

    • Discoverer: John Tebbutt
    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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    217
    Comet Halley

    Comet Halley

    • Discoverer: Edmond Halley
    Halley's Comet or Comet Halley ( /ˈhæli/) (rhymes with "alley" or "Sally"), officially designated 1P/Halley, is the best-known of the short-period comets and is visible from Earth every 75–76 years. Halley is the only short-period comet that is clearly visible to the naked eye from Earth, and thus the only naked-eye comet that might appear twice in a human lifetime. Other naked-eye comets may be brighter and more spectacular, but will appear only once in thousands of years. Halley's returns to the inner Solar System have been observed and recorded by astronomers since at least 240 BCE. Clear records of the comet's appearances were made by Chinese, Babylonian, and medieval European chroniclers, but were not recognized as reappearances of the same object at the time. The comet's periodicity was first determined in 1705 by English astronomer Edmond Halley, after whom it is now named. Halley's comet last appeared in the inner Solar System in 1986 and will next appear in mid-2061. During its 1986 apparition, Halley became the first comet to be observed in detail by spacecraft, providing the first observational data on the structure of a comet nucleus and the mechanism of coma and tail
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    218
    11 Parthenope

    11 Parthenope

    • Discoverer: Annibale de Gasparis
    • Discovery Site: Astronomical Observatory of Capodimonte
    11 Parthenope is a large, bright main-belt asteroid. Parthenope was discovered by Annibale de Gasparis on May 11, 1850, the second of his nine asteroid discoveries. It was named after Parthenopē, one of the Sirens in Greek mythology, said to have founded the city of Naples. De Gasparis "used his utmost endeavours to realise a 'Parthenope' in the heavens, such being the name suggested by Sir John Herschel on the occasion of the discovery of Hygeia in 1849". There have been two observed Parthenopian occultations, on February 13, 1987, and April 28, 2006. On August 6, 2008, during a perihelic opposition, Parthenope had an apparent magnitude of 8.8. In 2007, Baer and Chesley calculated a higher mass and density for Parthenope based on perturbations by the 90 km asteroid 17 Thetis. Baer and Chesley calculated a mass of 6.3×10 kg with a density of 3.3 g/cm³. 2008 estimates by Baer suggest a mass of 6.15×10. The 1997 and 2001 estimates by Viateau and Rapaport were closer to 5×10 kg with a density of 2.7 g/cm³.
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    219
    13 Egeria

    13 Egeria

    • Discoverer: Annibale de Gasparis
    • Discovery Site: Astronomical Observatory of Capodimonte
    13 Egeria is a large main-belt G-type asteroid. It was discovered by A. de Gasparis on November 2, 1850. Egeria occulted a star on January 8, 1992. Its disc was determined to be quite circular (217×196 km). On January 22, 2008, it occulted another star, and this occultation was timed by several observers in New Mexico and Arizona, coordinated by the IOTA Asteroid Occultation Program. The result showed that Egeria presented an approximately circular profile to Earth of 214.8x192 km, well in agreement with the 1992 occultation. It has also been studied by radar. Spectral analysis of Egeria shows it to be unusually high in water content, between 10.5-11.5% water by mass. This makes Egeria a prominent candidate for future water-mining ventures. Egeria was named by Urbain J. J. Le Verrier, whose computations led to the discovery of Neptune, after the mythological nymph Egeria of Aricia, Italy, the wife of Numa Pompilius, second king of Rome.
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    220
    1338 Duponta

    1338 Duponta

    • Discoverer: Louis Boyer
    • Discovery Site: Algiers Observatory
    1338 Duponta (1934 XA) is a main-belt asteroid discovered on December 4, 1934 by Boyer, L. at Algiers. Since the albedo of this asteroid is unknown, the size can only be estimated as between about 8 km - 19 km, based on the absolute magnitude (H) of 12.3. Photometric observations in 2007 revealed a ~3 km satellite (diameter ratio of 0.23) with an orbital period of 17.57 hours. Due to the similar size of the primary and secondary the Minor Planet Center lists this as a binary companion.
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    221
    1685 Toro

    1685 Toro

    • Discoverer: Carl A. Wirtanen
    • Discovery Site: Lick Observatory
    1685 Toro is an Apollo asteroid that orbits the Sun in an 5:8 resonance with Earth, and a near 5:13 resonance with Venus. Because of this unusual orbit, it is sometimes referenced as "Earth's second satellite". Toro was discovered by Carl A. Wirtanen at the Lick Observatory in 1948. It was the third Apollo asteroid to be discovered. The name honours Betulia Toro, wife of the astronomer Samuel Herrick. Herrick had studied the asteroid's orbit, and requested the name, along with that of 1580 Betulia. Based on orbital paths, 1685 Toro is the best candidate for the source of the Sylacauga meteorite, the only meteorite known to have injured a human being, when it struck and bruised Mrs. Ann Hodges of Sylacauga, Alabama, on 30 November 1954. 1685 Toro is reported to be an S-type asteroid composed of L chondrite.
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    222
    17 Thetis

    17 Thetis

    • Discoverer: Karl Theodor Robert Luther
    • Discovery Site: Düsseldorf-Bilk Observatory
    17 Thetis is a large main-belt asteroid. It is an S-type asteroid, therefore giving it a relatively bright silicate surface. It was discovered by R. Luther on April 17, 1852. It was his first asteroid discovery. Its name comes from Thetis, the mother of Achilles in Greek mythology. One Thetidian stellar occultation was observed from Oregon in 1999. However, the event was not timed. The mass of Thetis has been calculated from perturbations by 4 Vesta and 11 Parthenope. In 2007, Baer and Chesley calculated Thetis to have a mass of 1.2×10 kg with a density of 3.21 g/cm³.
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    1862 Apollo

    1862 Apollo

    • Discoverer: Karl Wilhelm Reinmuth
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    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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    19 Fortuna

    19 Fortuna

    • Discoverer: John Russell Hind
    • Discovery Site: George Bishop's Observatory, Regent's Park
    19 Fortuna is one of the largest main-belt asteroids. It has a composition similar to 1 Ceres: a darkly colored surface that is heavily space-weathered with the composition of primitive organic compounds, including tholins. Fortuna is 225 km in diameter and has one of the darkest known geometric albedos for an asteroid over 150 km in diameter. Its albedo has been measured at 0.028 and 0.037. The Hubble Space Telescope observed Fortuna in 1993. It was resolved with an apparent diameter of 0.20 arcseconds (4.5 pixels in the Planetary Camera) and its shape was found to be nearly spherical. Satellites were searched for but none were detected. Stellar occultations by Fortuna have been observed several times. Fortuna has been studied by radar. It was discovered by J. R. Hind on August 22, 1852 and named after Fortuna, the Roman goddess of luck. Fortuna has been perturbed by the 80 km 135 Hertha and was initially estimated by Baer to have a mass of 1.08×10 kg. A more recent estimate by Baer suggests it has a mass of 1.27×10 kg. On December 21, 2012 Fortuna (~200 km) will harmlessly pass within 6.5Gm of asteroid 687 Tinette.
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    2007 TU24

    2007 TU24

    • Discovery Organization: Catalina Sky Survey
    Asteroid 2007 TU24 was discovered by the Catalina Sky Survey in Arizona on October 11, 2007. Imaging radar has estimated that it is 250 meters (820 ft) in diameter. The asteroid passed 554,209 kilometer (344,370 mile or 1.4-lunar distance) from Earth on January 29, 2008, at 08:33 UTC. (At the time of the passage it was believed the closest for any known potentially hazardous asteroid (PHA) of this size before 2027, but in 2010 2005 YU55 was measured to be 400 meters in diameter.) At closest approach the asteroid had an apparent magnitude of 10.3 and was about 50 times fainter than the naked eye can see. It required about a 3-inch (76 mm) telescope to be seen. From the date of discovery of asteroid 2007 TU24 on 11 October 2007, a total of 316 observations of it had been made by 31 January 2008, spanning 112 days. The trajectory is well defined. It was removed from the 'current impact risks' page of the NASA website on 4 December 2007 at 14:05 UTC. Goldstone Observatory carried out radar observations on January 23 and January 24, 2008. As of January 24, the orbit of the asteroid was known with such a high precision that scientists were able to calculate close approaches from the year
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    226
    809 Lundia

    809 Lundia

    • Discoverer: Max Wolf
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    809 Lundia is a small, binary, V-type asteroid orbiting within the Flora family in the main belt. It is named after Lund Observatory, Sweden. Lundia orbits within the Flora family. However, its V-type spectrum indicates that it is not genetically related to the Flora family, but rather is probably a fragment (two fragments if one includes its moon) ejected from the surface of 4 Vesta by a large impact in the past. Its orbit lies too far from Vesta for it to actually be a member of the Vesta family. It is not clear how it arrived at an orbit so far from Vesta, but other examples of V-type asteroids orbiting fairly far from their parent body are known. A mechanism of interplay between the Yarkovsky effect and nonlinear secular resonances (primarily involving Jupiter and Saturn) has been proposed. Lightcurve observations in 2005 revealed that Lundia is a binary system of two similarly sized objects orbiting their common centre of gravity. "Lundia" now refers to one of the objects, the other being provisionally designated S/2005 (809) 1. The similarity of size between the two components is suspected because during mutual occultations the brightness drops by a similar amount
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    227
    9984 Gregbryant

    9984 Gregbryant

    • Discoverer: Robert H. McNaught
    • Discovery Site: Macquarie Observatory
    9984 Gregbryant is a main belt asteroid. It orbits the Sun once every 3.93 years. Discovered by R. H. McNaught and J. B. Child on April 18, 1996 it was given the provisional designation 1996 HT. It was later renamed 9984 Gregbryant after Greg Bryant, the editor of the Astronomical Society of New South Wales' journal.
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    228
    Tau Boötis Ab

    Tau Boötis Ab

    • Discoverer: Geoffrey Marcy
    Tau Boötis b, occasionally referred to as Tau Boötis Ab, is an extrasolar planet approximately 50 light-years away around the primary star of the Tau Boötis system in the constellation of Boötes. Announced in 1996 by Geoffrey Marcy and R. Paul Butler, Tau Boötis was one of the first stars confirmed to have planets orbiting it. On 16 December 1999, the planet was dubbed the "Millennium Planet" because the planet was then (erroneously) thought to be the first extrasolar planet to be discovered visually. Discovered in 1996, the planet is one of the first extrasolar planets found. It was discovered by Paul Butler and Geoffrey Marcy (San Francisco Planet Search Project) using the highly successful radial velocity method. Since the star is visually bright and the planet is massive, it produces a very strong velocity signal of 469 ± 5 metres per second, which was quickly confirmed by Michel Mayor and Didier Queloz from data collected over 15 years. It was later confirmed also by the AFOE Planet Search Team. Tau Boötis b is rather massive, with a minimum mass over four times that of Jupiter. It orbits the star in a so-called "torch orbit", at a distance from the star less than one seventh
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    229
    (53319) 1999 JM8

    (53319) 1999 JM8

    (53319) 1999 JM8 (also written (53319) 1999 JM8) is a near-Earth asteroid and Mars-crosser asteroid discovered by LINEAR. Radar imaging by Goldstone and Arecibo has revealed the asteroid to be 3.5 km in diameter. Like the asteroid 4179 Toutatis, its rotation speed is unusually slow and possibly chaotic. Its shape is bizarre, and is vaguely reminiscent of a roast chicken. It passed closer than 30 Gm to the Earth five times in the last century (5 Gm in 1990), but its closest approach in the 21st century will be at 38.3 Gm, in 2075.
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    230
    (55636) 2002 TX300

    (55636) 2002 TX300

    (55636) 2002 TX300 is a bright Kuiper belt object in the outer Solar System estimated to be about 286 km in diameter. It is a large member of the Haumea family, discovered on October 15, 2002, by the Near-Earth Asteroid Tracking (NEAT) program. A classical Kuiper belt object with the absolute magnitude between that of 50000 Quaoar and 20000 Varuna, 2002 TX300 has the most eccentric and inclined orbit of the three. A variability of the visual brightness was also detected which could fit to 7.9 h or 15.8 h rotational period (the distinction between single or double-peaked curved could not be made with confidence). The changes in brightness are quite close to the error margin and could also be due to an irregular shape. 2002 TX300 is classified as a classical Kuiper belt object and follows an orbit very similar to that of Haumea: highly inclined (26°) and moderately eccentric (e ~0.12), far from Neptune’s perturbations (perihelion at ~37 AU). Other mid-sizes cubewanos follow similar orbits as well, notably 2002 UX25 and 2002 AW197. The diagrams show polar and ecliptic views of the orbits of the two cubewanos. The perihelia (q) and the aphelia (Q) are marked with the dates of passage.
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    231
    1000 Piazzia

    1000 Piazzia

    • Discoverer: Karl Wilhelm Reinmuth
    • Discovery Site: Landessternwarte Heidelberg-Königstuhl
    1000 Piazzia, discovered in 1923, is a main-belt asteroid orbiting the Sun. It was the 1000th minor planet to be numbered, and was named in honour of Giuseppe Piazzi, who discovered the first asteroid, 1 Ceres. Its radius is estimated to be 24 km, and measurements of its light curve by Robert D. Stephens in 2001 showed it to be rotating with a period of 9.47 hours. The planet Piazzia comes closest to is Mars. It draws nearer than 1.33 AU eleven times in the 20th and 21st centuries. Rarely, the two are closer than one AU. This last happened in 1638, and won't happen again for another 14,000 years.
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    232
    16 Cygni B b

    16 Cygni B b

    16 Cygni Bb or 16 Cyg Bb is an extrasolar planet approximately 70 light-years away in the constellation of Cygnus. The planet was discovered orbiting the sun-like star 16 Cygni B, one of two solar-mass components of the triple star system 16 Cygni. It makes one revolution every 799 days and was the first eccentric Jupiter to be discovered. In October 1996 the discovery of a planetary-mass companion to the star 16 Cygni B was announced, with a mass at least 1.68 times that of Jupiter. At the time, it had the highest orbital eccentricity of any known extrasolar planet. The discovery was made by measuring the star's radial velocity. As the inclination of the orbit is unknown, only a lower limit on the mass is known. Unlike the planets in our solar system, the planet's orbit is highly elliptical, and its distance varies from 0.54 AU at periastron to 2.8 AU at apastron. This high eccentricity may have been caused by tidal interactions in the binary star system, and the planet's orbit may vary chaotically between low and high-eccentricity states over a period of tens of millions of years. The lower limit for the object's mass is well below the dividing line between planets and brown
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    2 Pallas

    2 Pallas

    • Discoverer: Heinrich Wilhelm Matthäus Olbers
    Pallas, formally designated 2 Pallas, is the second asteroid to have been discovered (after Ceres), and one of the largest in the Solar System. It is estimated to comprise 7% of the mass of the asteroid belt, and its diameter of 544 kilometres (338 mi) is slightly larger than that of 4 Vesta. It is however 10–30% less massive than Vesta, placing it third among the asteroids. It is possibly the largest irregularly shaped body in the Solar System (that is, the largest body not rounded under its own gravity), and a remnant protoplanet. When Pallas was discovered by astronomer Heinrich Wilhelm Matthäus Olbers on March 28, 1802, it was counted as a planet, as were other asteroids in the early 19th century. The discovery of many more asteroids after 1845 eventually led to their re-classification. The Palladian surface appears to be a silicate material; the surface spectrum and estimated density resemble carbonaceous chondrite meteorites. The Palladian orbit, at 34.8°, is unusually highly inclined to the plane of the asteroid belt, and the orbital eccentricity is nearly as large as that of Pluto, making Pallas relatively inaccessible to spacecraft. 2 Pallas is named after Pallas Athena,
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    234
    2004 HR56

    2004 HR56

    2004 HR56 (also written 2004 HR56) is a small Earth-crossing asteroid belonging to the Apollo family and was visible between April 25 to May 10, 2005. This find was documented as part of the FMO Project and was reported by six different observatories. Reports indicate that the object is about 74 metres wide and has an absolute magnitude of 23.28. The object could also be classified as a meteoroid, although the most common definition uses a diameter of 10 m as the demarcation.
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    235
    2004 XP14

    2004 XP14

    2004 XP14 (also written 2004 XP14) is a near-Earth asteroid, first discovered on December 10, 2004, by the LINEAR project. Due to the proximity of its orbit to Earth and its estimated size, this object has been classified as a "Potentially Hazardous Asteroid" (PHA) by the Minor Planet Center in Cambridge, Massachusetts. Although initially there were concerns that it might possibly impact Earth later in the 21st century and thus merit special monitoring, further analysis of its orbit has since ruled out any such collision, at least in the foreseeable future. The size of 2004 XP14 is not precisely known. Based on optical measurements, the object is between 300 and 900 meters in diameter. 2004 XP14's closest pass by Earth was above the west coast of North America at 04:25 UTC on July 3, 2006. The asteroid's distance from Earth's center of mass at that moment was 0.0028906 AU (432,430 km; 268,700 mi), or just 1.1 times the Moon's average distance from Earth. It was observed immediately after this close approach by radar from three locations, from Goldstone in the Mojave Desert in the USA, from Sicily, and from Yevpatoria RT-70 radio telescope, Ukraine, as well as optically from other
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    2007 VK184

    2007 VK184

    2007 VK184 is an asteroid which is listed on the Near-Earth Object Risk List with a rating on the Torino Scale of Level 1. A Torino rating of 1 is a routine discovery in which a pass near the Earth is predicted that poses no unusual level of danger. As of 24 June 2011 (2011 -06-24), 2007 VK184 and 2011 AG5 are the only near-earth objects to be listed above Level 0 for potential impacts within 100 years. 2007 VK184 was discovered on November 12, 2007, by the Catalina Sky Survey. Further observations between December 18, 2007, and January 4, 2008, suggested an increase in the impact probability to 1 in 2700 chance for an impact with Earth during June 2048. A few days later, the impact probability was reverted back to a 1 in 3030 chance. According to the Near-Earth Object list, 101 observations over 60 days suggests the asteroid has a probability of 1 in 1820 chance of hitting the Earth on June 3, 2048 at a distance of about 0.75 Earth radii (4815km). Those figures translate into a 0.055% chance of hitting (or 99.945% of missing). The nominal close approach is 0.032 AU (4,800,000 km; 3,000,000 mi) on 2048-May-30. The asteroid is estimated to have a diameter of about 130 meters.
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    39 Laetitia

    39 Laetitia

    • Discoverer: Jean Chacornac
    • Discovery Site: Paris Observatory
    39 Laetitia ( /lɨˈtiːʃiə/) is a large, bright main-belt asteroid. Laetitia was discovered by J. Chacornac on February 8, 1856, and named after Laetitia, a minor Roman goddess of gaiety. Observations of an occultation on March 21, 1998, produced several chords indicating an ellipsoid of 219×142 km.
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    238
    3908 Nyx

    3908 Nyx

    • Discoverer: Hans-Emil Schuster
    • Discovery Site: La Silla Observatory
    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.
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    239
    55 Cancri d

    55 Cancri d

    • Discoverer: Geoffrey Marcy
    55 Cancri d (abbreviated 55 Cnc d) is an extrasolar planet in a long-period orbit around the Sun-like star 55 Cancri A. Located at a similar distance from its star as Jupiter is from our Sun, it is the fifth and outermost known planet in its planetary system. 55 Cancri d was discovered on June 13, 2002. Like the majority of known extrasolar planets, 55 Cancri d was detected by observing changes in its star's radial velocity. This was achieved by making sensitive measurements of the Doppler shift of the star's spectrum. At the time of discovery, 55 Cancri A was already known to possess one planet (55 Cancri b), however there was still a drift in the radial velocity measurements which was unaccounted-for. In 2002, further measurements revealed the presence of a long-period planet in an orbit at around 5 AU from the star. The same measurements also indicated the presence of another inner planet, designated 55 Cancri c. When 55 Cancri d was discovered, it was thought to be on a fairly low eccentricity orbit similar to Jupiter in our solar system, though the orbital elements were not well determined. As more data were collected, the best-fit solution for this planet turned out to be
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    240
    690 Wratislavia

    690 Wratislavia

    • Discoverer: Joel Hastings Metcalf
    • Discovery Site: Taunton observatory
    690 Wratislavia is a minor planet orbiting the Sun. Wratislavia was discovered on October 16, 1909. IRAS data shows it is about 135 km in diameter. Wratislavia has been studied by radar.
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    241
    9974 Brody

    9974 Brody

    • Discoverer: Eric Walter Elst
    • Discovery Site: La Silla Observatory
    9974 Brody is a main belt asteroid. It orbits the Sun once every 3.70 years. Discovered on July 19, 1993 by E. W. Elst, it was given the provisional designation 1993 OG13. It was later renamed "Brody" after Adrien Brody, who portrayed the character Wladyslaw Szpilman in The Pianist.
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    242
    Arietids

    Arietids

    • Discovery Site: Jodrell Bank Observatory
    The Arietids are a strong meteor shower that lasts from May 22 to July 2 each year, and peaks on June 7. The Arietids, along with the Zeta Perseids, are the most intense daylight meteor showers of the year. The source of the shower is unknown, but scientists suspect that they come from the asteroid 1566 Icarus, although the orbit also corresponds similarly to 96P/Machholz. First discovered at Jodrell Bank Observatory in England during the summer of 1947, the showers are caused when the Earth passes through a dense portion of two interplanetary meteoroid streams, producing an average of 60 shooting stars each hour, that originate in the sky from the constellation Aries and the constellation Perseus. However, because both constellations are so close to the Sun when these showers reach their peak, the showers are difficult to view with the naked eye. Some of the early meteors are visible in the very early hours of the morning, usually an hour before dawn. The meteors strike Earth's atmosphere at 39 km/s.
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    243
    C/1811 F1

    C/1811 F1

    • Discoverer: Honoré Flaugergues
    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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    Comet Encke

    Comet Encke

    Comet Encke or Encke's Comet (official designation: 2P/Encke) is a periodic comet that completes an orbit of the Sun once every three years — the shortest period of any known comet. It was first recorded by Pierre Méchain in 1786, but it was not recognized as a periodic comet until 1819 when its orbit was computed by Johann Franz Encke; like Halley's Comet, it is unusual in being named after the calculator of its orbit rather than its discoverer. As its official designation implies, Encke's Comet was the first periodic comet discovered after Halley's Comet (designated 1P/Halley). Its orbit was calculated by Johann Franz Encke, who through laborious calculations was able to link observations of comets in 1786 (designated 2P/1786 B1), 1795 (2P/1795 V1), 1805 (2P/1805 U1) and 1818 (2P/1818 W1) to the same object. In 1819 he published his conclusions in the journal Correspondance astronomique, and predicted correctly its return in 1822 (2P/1822 L1). The diameter of the nucleus of Encke's Comet is 4.8 km. Comets are in unstable orbits that evolve over time due to perturbations and outgassing. Given Encke's low orbital inclination near the ecliptic and brief orbital period of 3 years,
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    Comet Ikeya-Seki

    Comet Ikeya-Seki

    • Discoverer: Kaoru Ikeya
    Comet Ikeya–Seki, formally designated C/1965 S1, 1965 VIII, and 1965f, was a long-period comet discovered independently by Kaoru Ikeya and Tsutomu Seki. First observed as a faint telescopic object on September 18, 1965, the first calculations of its orbit suggested that on October 21, it would pass just 450,000 km above the Sun's surface, and would probably become extremely bright. Comets can defy such predictions, but Ikeya–Seki performed as expected. As it approached perihelion observers reported that it was clearly visible in the daytime sky next to the Sun. In Japan, where it reached perihelion at local noon, it was seen shining at magnitude −10. It proved to be one of the brightest comets seen in the last thousand years, and is sometimes known as the Great Comet of 1965. The comet was seen to break into three pieces just before its perihelion passage. The three pieces continued in almost identical orbits, and the comet re-appeared in the morning sky in late October, showing a very bright tail. By early 1966, it had faded from view as it receded into the outer solar system. Ikeya–Seki is a member of the Kreutz Sungrazers, which are suggested to be fragments of a large comet
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    Comet White-Ortiz-Bolelli

    Comet White-Ortiz-Bolelli

    Comet White–Ortiz–Bolelli (formal designations: C/1970 K1, 1970 VI, and 1970f) was a bright comet which appeared in 1970. It was a member of the Kreutz Sungrazers, a family of comets which resulted from the break-up of a large parent comet several centuries ago. It was already easily visible to the naked eye when first discovered, and reached a maximum apparent magnitude of +1. Comet White–Ortiz–Bolelli was first spotted on May 18 by Graeme White, an Australian amateur astronomer in Wollongong, New South Wales. He sighted the comet in binoculars shortly after sunset, and described it as having a star-like head at apparent magnitude 1-2, and a short tail about 1 degree long. He spotted it again on May 20 by naked eye as well as binoculars, and by this time the tail had grown to 10° in length. The second independent discovery was made on May 21 by Air France pilot Emilio Ortiz, from a location about 400 km east of Madagascar. Ortiz saw the comet from his cockpit, and reported a magnitude of 0.5 to 1.0 and a tail about 5–8° long. A few hours later, Carlos Bolelli, a technician at the Cerro Tololo Inter-American Observatory in Chile became the third independent discoverer of the comet,
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    Comet Yi-SWAN

    Comet Yi-SWAN

    Comet C/2009 F6 (Yi–SWAN) is a non-periodic comet which appeared in March 2009. It was first discovered by Korean amateur astronomer Dae-am Yi on March 26, 2009, using a Canon 5D camera and 90-mm lens. It is believed to be the first comet discovered by a Korean in the modern age. Independently, on April 4 Rob Matson reported he had discovered a comet in the SWAN instrument photographs on the SOHO (Solar and Heliospheric Observatory) spacecraft website. The comet was not bright enough to be seen by the naked eye, but was theoretically visible through amateur telescopes. However, it was harder to see than predicted, as it remained quite small and did not form much of a visible tail. It reached a peak magnitude around +8.5 in April into May, and passed 1.5 degrees south of the Double cluster in Perseus on April 23.
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    HD 149026 b

    HD 149026 b

    • Discoverer: Debra Fischer
    HD 149026 b is an extrasolar planet approximately 257 light-years away in the constellation of Hercules. The planet was discovered after it transited its parent star, HD 149026. It is notable for the presence of an exceptionally large planetary core suggested by measurements of its radius and mass. The planet was discovered by the N2K Consortium in 2005, which searches stars for closely orbiting giant planets similar to 51 Pegasi b using the highly successful radial velocity method. The spectrum of the star was studied from the Keck and Subaru Telescopes. After the planet was first detected from the Doppler effect it caused in the light of the host star, it was studied for transits at the Fairborn Observatory. A tiny decrease of light (0.003 magnitudes) was detected every time the planet was transiting the star, thus confirming its existence. Although the change of brightness caused by the transiting planet is tiny, it is detectable by amateur astronomers, providing an opportunity for amateurs to make important astronomical contributions. Indeed, one amateur astronomer, Ron Bissinger, actually detected a partial transit a day before the discovery was published. The planet's orbit
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    NGC 6027

    NGC 6027

    • Discoverer: Édouard Jean-Marie Stephan
    NGC 6027 is a Lenticular galaxy that is the brightest member of Seyfert's Sextet, a compact group of galaxies. Édouard Stephan discovered the galaxy in 1882.
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    250
    Uranus

    Uranus

    • Discoverer: William Herschel
    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).
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