Any celestial body (other than stars) that is part of a star system (including the Earth's solar system. This can include planets, dwarf planets, asteroids, comets, meteoroids, and so on. In practice, outside of the Solar System, this will type will be used primarily for exoplanets.
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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
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.
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.
Venus is the second planet from the Sun, orbiting it every 224.7 Earth days. The planet is named after the Roman goddess of love and beauty. After the Moon, it is the brightest natural object in the night sky, reaching an apparent magnitude of −4.6, bright enough to cast shadows. Because Venus is an inferior planet from Earth, it never appears to venture far from the Sun: its elongation reaches a maximum of 47.8°. Venus reaches its maximum brightness shortly before sunrise or shortly after sunset, for which reason it has been referred to by ancient cultures as the Morning Star or Evening Star.
Venus is classified as a terrestrial planet and is sometimes called Earth's "sister planet" owing to their similar size, gravity, and bulk composition (Venus is both the closest planet to Earth and the planet closest in size to Earth). However, it has been shown to be very different from Earth in other respects. Venus is shrouded by an opaque layer of highly reflective clouds of sulfuric acid, preventing its surface from being seen from space in visible light. It has the densest atmosphere of the four terrestrial planets, consisting mostly of carbon dioxide. The atmospheric pressure at the
(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 =
90377 Sedna is a large trans-Neptunian object, which as of 2012 was about three times as far from the Sun as Neptune. Spectroscopy has revealed that Sedna's surface composition is similar to that of some other trans-Neptunian objects, being largely a mixture of water, methane and nitrogen ices with tholins. Its surface is one of the reddest in the Solar System. Neither its mass nor its size are well known and the IAU has not formally recognized it as a dwarf planet, though it is thought to be one by several astronomers.
For most of its orbit it is even farther from the Sun than at present, with its aphelion estimated at 960 astronomical units (32 times Neptune's distance), making it one of the most distant known objects in the Solar System other than long-period comets. Sedna's exceptionally long and elongated orbit, taking approximately 11,400 years to complete, and distant point of closest approach to the Sun, at 76 AU, have led to much speculation as to its origin. The Minor Planet Center currently places Sedna in the scattered disc, a group of objects sent into highly elongated orbits by the gravitational influence of Neptune. However, this classification has been contested, as
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.
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,
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
144P/Kushida is a periodic comet discovered in January, 1994, by Yoshio Kushida at the Yatsugatake South Base Observatory in Japan. This was the first comet discovery of 1994 and his second discovery within a month.
Based on data gathered during the period of January 9 - 11, 1994 Syuichi Nakano calculated the date of perihelion to be 1993 December 5.33 and the distance of perihelion as 1.36 AU. The low inclination to the ecliptic suggested to Nakano that the comet could be a short period type. On January 14, 1994 Daniel W. E. Green confirmed Nakano's suggestion and published a short-period orbit on IAU Circular 5922. Based on 29 positions obtained during the period of January 9-13, Green determined a perihelion date of 1993 December 12.99, a perihelion distance of 1.37 AU, and an orbital period of 7.20 years.
Using over 300 positions obtained between January 7 and July 9, 1994 Patrick Rocher refined the calculations and determined the perihelion distance as 1.367 AU, the perihelion date as 1993 December 12.862, and the orbital period as 7.366 years.
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.
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
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.
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.
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
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.
Callisto /kəˈlɪstoʊ/ (Jupiter IV) is a moon of the planet Jupiter. It was discovered in 1610 by Galileo Galilei. It is the third-largest moon in the Solar System and the second largest in the Jovian system, after Ganymede. Callisto has about 99% the diameter of the planet Mercury but only about a third of its mass. It is the fourth Galilean moon of Jupiter by distance, with an orbital radius of about 1,880,000 km. It does not form part of the orbital resonance that affects three inner Galilean satellites—Io, Europa and Ganymede—and thus does not experience appreciable tidal heating. Callisto's rotation is tidally locked to its revolution around Jupiter, so that the same hemisphere always faces inward; Jupiter appears to stand still in Callisto's sky. Callisto is less affected by Jupiter's magnetosphere than the other inner satellites because it orbits farther away.
Callisto is composed of approximately equal amounts of rock and ices, with a mean density of about 1.83 g/cm. Compounds detected spectroscopically on the surface include water ice, carbon dioxide, silicates, and organic compounds. Investigation by the Galileo spacecraft revealed that Callisto may have a small silicate
(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.
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
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
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
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
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
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
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
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.
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
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.
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
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.
Io /ˈaɪ.oʊ/ is the innermost of the four Galilean moons of the planet Jupiter and, with a diameter of 3,642 kilometres (2,263 mi), the fourth-largest moon in the Solar System. It was named after the mythological character of Io, a priestess of Hera who became one of the lovers of Zeus.
With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's interior as it is pulled between Jupiter and the other Galilean satellites—Europa, Ganymede and Callisto. Several volcanoes produce plumes of sulfur and sulfur dioxide that climb as high as 500 km (300 mi) above the surface. Io's surface is also dotted with more than 100 mountains that have been uplifted by extensive compression at the base of the moon's silicate crust. Some of these peaks are taller than Earth's Mount Everest. Unlike most satellites in the outer Solar System, which are mostly composed of water-ice, Io is primarily composed of silicate rock surrounding a molten iron or iron sulfide core. Most of Io's surface is characterized by extensive plains coated with sulfur and sulfur dioxide frost.
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.
2005 YU55, also written as 2005 YU55, is a potentially hazardous asteroid 310 meters or about 400 m (1,300 feet) in diameter. It was discovered on 28 December 2005 by Robert S. McMillan at Steward Observatory, Kitt Peak. On 8 November 2011 it passed 0.85 lunar distances (324,900 kilometers; 201,900 miles) from the Earth. This is the closest known approach by an asteroid with an absolute magnitude this bright since 2010 XC15 (H = 21.4) approached within 0.5 lunar distances in 1976.
In February 2010, 2005 YU55 was rated 1 on the Torino Scale, indicating that a pass near the Earth poses no unusual level of danger. On 19 April 2010, radar ranging by the Arecibo radio telescope reduced uncertainties about the orbit by 50%. This improvement eliminated any possibility of an impact with the Earth within the next 100 years. It was removed from the Sentry Risk Table on 22 April 2010 and as such it now has a rating of 0 on the Torino Scale.
On 8 November 2011 at 23:28 UT the asteroid passed 0.8453 LD (324,900 km; 201,900 mi) from the Earth. On 9 November 2011 at 07:13 UT the asteroid passed 0.6231 LD (239,500 km; 148,800 mi) from the Moon. During the close approach the asteroid reached about
Enceladus is the sixth-largest of the moons of Saturn. It was discovered in 1789 by William Herschel.
Enceladus seems to have liquid water under its icy surface. Cryovolcanoes at the south pole shoot large jets of water ice particles into space. Some of this water falls back onto the moon as "snow", some of it adds to Saturn's rings, and some of it reaches Saturn. Because of this apparent water at or near the surface, Enceladus may be one of the best places for humans to look for extraterrestrial life. By contrast, the water thought to be on Jupiter's moon Europa is locked under a very thick layer of surface ice.
Until the two Voyager spacecraft passed near it in the early 1980s very little was known about this small moon besides the identification of water ice on its surface. The Voyagers showed that the diameter of Enceladus is only 500 kilometers (310 mi), about a tenth of that of Saturn's largest moon, Titan, and that it reflects almost all of the sunlight that strikes it. Voyager 1 found that Enceladus orbited in the densest part of Saturn's diffuse E ring, indicating a possible association between the two, while Voyager 2 revealed that despite the moon's small size, it had a
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.
Jupiter is the fifth planet from the Sun and the largest planet in the Solar System. It is a gas giant with mass one-thousandth that of the Sun but is two and a half times the mass of all the other planets in our Solar System combined. Jupiter is classified as a gas giant along with Saturn, Uranus and Neptune. Together, these four planets are sometimes referred to as the Jovian or outer planets. The planet was known by astronomers of ancient times, and was associated with the mythology and religious beliefs of many cultures. The Romans named the planet after the Roman god Jupiter. When viewed from Earth, Jupiter can reach an apparent magnitude of −2.94, making it on average the third-brightest object in the night sky after the Moon and Venus. (Mars can briefly match Jupiter's brightness at certain points in its orbit.)
Jupiter is primarily composed of hydrogen with a quarter of its mass being helium, although helium only comprises about a tenth of the number of molecules. It may also have a rocky core of heavier elements, but like the other gas giants, Jupiter lacks a well-defined solid surface. Because of its rapid rotation, the planet's shape is that of an oblate spheroid (it
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
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.
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
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.
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.
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.
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.
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.
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.
The asteroid 12306 Pebronstein is a main belt asteroid discovered by Charles de Saint-Aignan at Lowell Observatory, examining films taken at Palomar.
Peter Bronstein (b. 1947) is father in-law of the discoverer. An avid sailor, Bronstein is always happy to share his time and his boat with others †
This orbital diagram is courtesy of the JPL Small-Body Database Browser
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.
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.
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
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
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
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
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.
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
(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),
(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
(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.
Comet Holmes (official designation: 17P/Holmes) is a periodic comet in the Solar System, discovered by the British amateur astronomer Edwin Holmes on November 6, 1892. Although normally a very faint object, Holmes became notable during its October 2007 return when it temporarily brightened by a factor of about half a million, in what was the largest known outburst by a comet, and became visible to the naked eye. It also briefly became the largest object in the solar system, as its coma (the thin dissipating dust ball around the comet) expanded to a diameter greater than that of the Sun (although its mass remained minuscule).
Comet Holmes was discovered by Edwin Holmes on November 6, 1892, while he was conducting regular observations of the Andromeda Galaxy (M31). Its discovery in 1892 was possible because of an increase in its magnitude similar to the 2007 outburst; it brightened to an approximate magnitude of 4 or 5 before fading from visibility over a period of several weeks.
The comet's discovery was confirmed by Edward Walter Maunder (Royal Observatory, Greenwich, England), William Henry Maw (England), and Kidd (Bramley, England) and independent discoveries were made by Thomas
(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.
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
(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.
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
2011 MD is an Apollo asteroid that passed relatively close to Earth's surface — at a distance of about 12,000 kilometers (7,500 mi), roughly the diameter of the Earth — at around 17:00 UTC (13:00 EDT) on June 27, 2011. Although the object was initially believed to be space junk, subsequent observations confirmed that it is an asteroid.
A few hours before the asteroid's nearest approach in 2011, it appeared close to the Sun, so observations were possible for only a brief period. Backyard astronomers were able to observe it with telescopes from Australia, southern Africa, and the Americas.
The asteroid was discovered on June 22, 2011, by the Lincoln Near-Earth Asteroid Research (LINEAR) pair of robotic telescopes in New Mexico, and according to original rough estimates, the asteroid's length was between 10 and 45 meters (30 and 150 ft). But based on the more recent absolute magnitude (H) of 28.1, the asteroid would be closer to 7 to 15 meters in diameter.
Emily Baldwin of Astronomy Now said that there was no threat of collision, and should the asteroid enter Earth's atmosphere, it would "mostly burn up in a brilliant fireball, possibly scattering a few meteorites", causing no likely
52872 Okyrhoe ( /əˈkɪroʊ.iː/; from Greek: Ωκυρόη, Ωκυρρόη) is a centaur orbiting in the outer Solar System between Jupiter and Neptune. It was discovered on September 19, 1998, by Spacewatch.
Centaurs have short dynamical lives due to strong interactions with the giant planets. Okyrhoe (1998 SG35) is estimated to have an orbital half-life of about 670 kiloannum.
Of objects listed as a centaur by the Minor Planet Center (MPC), JPL, and the Deep Ecliptic Survey (DES), Okyrhoe has the second smallest perihelion distance. Recently discovered 2008 QD4 has a smaller perihelion distance.
Okyrhoe passed perihelion in early 2008, and exhibited important magnitude variations during March and April 2008. This could be a sign of sublimation of volatiles.
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
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
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.
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
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 .
2010 TK7 is the first Earth trojan asteroid to be discovered; it precedes Earth in its orbit around the Sun. Trojan objects are most easily conceived as orbiting at a Lagrangian point, a dynamically stable location (where gravitational and centrifugal forces balance) 60 degrees ahead of or behind a massive orbiting body, in a type of 1:1 orbital resonance. In reality, they oscillate (librate) around such a point. Such objects had previously been observed only in the orbits of Mars, Jupiter, Neptune and several moons of Saturn.
2010 TK7 has a diameter of about 300 meters (1,000 ft). Its path oscillates about the Sun–Earth L4 Lagrangian point (60 degrees ahead of Earth), shuttling between its closest approach to Earth and its closest approach to the L3 point (180 degrees from Earth) about every 400 years.
The asteroid was discovered in October 2010 by the NEOWISE team of astronomers using NASA's Wide-field Infrared Survey Explorer (WISE).
WISE, a space telescope launched into Earth orbit in December 2009, imaged 2010 TK7 in October 2010 while carrying out a program to scan the entire sky from January 2010 to February 2011. Spotting an asteroid sharing Earth's orbit is normally
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.
The Moon (Latin: luna) is the only natural satellite of the Earth, and the fifth largest satellite in the Solar System. It is the largest natural satellite of a planet in the Solar System relative to the size of its primary, having 27% the diameter and 60% the density of Earth, resulting in ⁄81 its mass. The Moon is the second densest satellite after Io, a satellite of Jupiter.
The Moon is in synchronous rotation with Earth, always showing the same face with its near side marked by dark volcanic maria that fill between the bright ancient crustal highlands and the prominent impact craters. It is the brightest object in the sky after the Sun, although its surface is actually very dark, with a reflectance similar to that of coal. Its prominence in the sky and its regular cycle of phases have, since ancient times, made the Moon an important cultural influence on language, calendars, art and mythology. The Moon's gravitational influence produces the ocean tides and the minute lengthening of the day. The Moon's current orbital distance, about thirty times the diameter of the Earth, causes it to appear almost the same size in the sky as the Sun, allowing it to cover the Sun nearly
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.
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.
9992 1997 TG19 is a Mars crossing asteroid. It orbits the Sun once every 3.20 years.
It was discovered on October 8, 1997 by Tetsuo Kagawa and Takeshi Urata at the Gekko Observatory, and given the provisional designation 1997 TG19.
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.
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
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:
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.
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.
Ariel is the fourth-largest of the 27 known moons of Uranus. Ariel orbits and rotates in the equatorial plane of Uranus, which is almost perpendicular to the orbit of Uranus, and so has an extreme seasonal cycle.
It was discovered in October 1851 by William Lassell, and named for a character in two different pieces of literature. As of 2012, much of the detailed knowledge of Ariel derives from a single flyby of Uranus performed by the spacecraft Voyager 2 in 1986, which managed to image around 35% of the moon's surface. There are no active plans at present to return to study the moon in more detail, although various concepts such as Uranus orbiter and probe are proposed from time to time.
After Miranda, Ariel is the second-smallest of Uranus' five major rounded satellites, and the second-closest to its planet. Among the smallest of the Solar System's 19 known spherical moons (it ranks 14th among them in diameter), it is believed to be composed of roughly equal parts ice and rocky material. Like all of Uranus' moons, Ariel probably formed from an accretion disc that surrounded the planet shortly after its formation, and, like other large moons, it is likely differentiated, with an
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
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
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.
(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.
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.
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
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.
9972 Minoruoda is a C-type main belt asteroid. It orbits the Sun once every 3.46 years.
Discovered on May 26, 1993 by S. Otomo it was given the provisional designation 1993 KQ. It was later renamed "Minoruoda" after Minoru Oda, a former director general of the Institute of Space and Astronautical Science.
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.
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
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
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.
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
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
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,
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
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
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
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
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.
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
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
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Named after the Roman god Saturn, its astronomical symbol (♄) represents the god's sickle. Saturn is a gas giant with an average radius about nine times that of Earth. While only one-eighth the average density of Earth, with its larger volume Saturn is just over 95 times as massive as Earth.
Saturn's interior is probably composed of a core of iron, nickel and rock (silicon and oxygen compounds), surrounded by a deep layer of metallic hydrogen, an intermediate layer of liquid hydrogen and liquid helium and an outer gaseous layer. The planet exhibits a pale yellow hue due to ammonia crystals in its upper atmosphere. Electrical current within the metallic hydrogen layer is thought to give rise to Saturn's planetary magnetic field, which is slightly weaker than Earth's and around one-twentieth the strength of Jupiter's. The outer atmosphere is generally bland and lacking in contrast, although long-lived features can appear. Wind speeds on Saturn can reach 1,800 km/h (1,100 mph), faster than on Jupiter, but not as fast as those on Neptune.
Saturn has a prominent ring system that
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
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
Oberon, also designated Uranus IV, is the outermost major moon of the planet Uranus. It is the second largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies who appears as a character in Shakespeare's A Midsummer Night's Dream. Its orbit lies partially outside Uranus's magnetosphere.
It is likely that Oberon formed from the accretion disk that surrounded Uranus just after the planet's formation. The moon consists of approximately equal amounts of ice and rock, and is probably differentiated into a rocky core and an icy mantle. A layer of liquid water may be present at the boundary between the mantle and the core. The surface of Oberon, which is dark and slightly red in color, appears to have been primarily shaped by asteroid and comet impacts. It is covered by numerous impact craters reaching 210 km in diameter. Oberon possesses a system of chasmata (graben or scarps) formed during crustal extension as a result of the expansion of its interior during its early evolution.
The Uranian system has been studied up close only once: the
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).
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.
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.
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.
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.
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
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
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.
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.
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.
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.
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.
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.
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.
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
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,
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
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
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.
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.
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,
(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".
The asteroid 12373 Lancearmstrong is a Main belt asteroid discovered by Charles de Saint-Aignan at Lowell Observatory, examining films taken at Palomar.
Lance Armstrong (b. 1971) is an American cyclist and cancer survivor. After being diagnosed with advanced testicular cancer in 1996, he was able to return to cycling and win the Tour de France a record seven consecutive times. He serves as an inspiration to cancer survivors and athletes around the world †.
This orbital diagram is courtesy of the JPL Small-Body Database Browser
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
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.
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.
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
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
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
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
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
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
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.
Mimas is a moon of Saturn which was discovered in 1789 by William Herschel. It is named after Mimas, a son of Gaia in Greek mythology, and is also designated Saturn I.
With a diameter of 396 kilometres (246 mi) it is the twentieth-largest moon in the Solar System and is the smallest astronomical body that is known to be rounded in shape because of self-gravitation.
Mimas was discovered by the astronomer William Herschel on 17 September 1789. He recorded his discovery as follows: "The great light of my forty-foot telescope was so useful that on the 17th of September, 1789, I remarked the seventh satellite, then situated at its greatest western elongation."
Mimas is named after one of the Titans in Greek mythology, Mimas. The names of all seven then-known satellites of Saturn, including Mimas, were suggested by William Herschel's son John in his 1847 publication Results of Astronomical Observations made at the Cape of Good Hope. He named them after Titans specifically because Saturn (the Roman equivalent of Kronos in Greek mythology), was the leader of the Titans and ruler of the world for some time.
The adjectival form of Mimas is Mimantean or Mimantian, and this is accepted by the
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
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.
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.
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
(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
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.
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.
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.
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
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.
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".
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.
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
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
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
Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets. It is sometimes referred to as the world, the Blue Planet, or by its Latin name, Terra.
Earth formed approximately 4.54 billion years ago by accretion from the solar nebula, and life appeared on its surface within one billion years. The planet is home to millions of species, including humans. Earth's biosphere has significantly altered the atmosphere and other abiotic conditions on the planet, enabling the proliferation of aerobic organisms as well as the formation of the ozone layer, which together with Earth's magnetic field blocks harmful solar radiation, thus permitting formerly ocean-confined life to move safely to land. The physical properties of the Earth, as well as its geological history and orbit, have allowed life to persist. Estimates on how much longer the planet will to be able to continue to support life range from 500 million years, to as long as 2.3 billion years.
Earth's crust is divided into several rigid segments, or tectonic plates, that migrate across the surface over periods
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
10002 Bagdasarian is a main belt asteroid orbiting the Sun. It completes one orbit ever 5.6 years.
The asteroid was discovered by L. I. Chernykh at the Crimean Astrophysical Observatory, and given the provisional designation 1969 TQ1. It was later renamed for Alexandr Sergeevich Bagdasarian, a radio and electronics specialist from Moscow.
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.
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.
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.
8405 Asbolus ( /ˈæzbɵləs/; from Greek: Άσβολος) is a centaur orbiting between the orbits of Jupiter and Neptune. It was discovered by James V. Scotti and Robert Jedicke of Spacewatch at Kitt Peak Observatory on April 5, 1995. It is named after Asbolus (Greek for sooty), a centaur in Greek mythology. Its provisional designation was 1995 GO.
Observations with the Spitzer Space Telescope in 2007 resulted in a diameter calculation of about 84 ± 8 km.
No resolved images of it have ever been made but, in 1998, spectral analysis of its composition by the Hubble Space Telescope revealed a fresh impact crater on its surface, less than 10 million years old. Centaurs are dark in colour, because their icy surfaces have darkened after long exposure to solar radiation and the solar wind. However, fresh craters excavate more reflective ice from below the surface, and that is what Hubble has detected on Asbolus.
Centaurs have short dynamical lifetimes due to perturbations by the giant planets. Asbolus is estimated to have an orbital half-life of about 860 kiloannum. Asbolus is currently classified as a SN centaur since Saturn is considered to control the perihelion and Neptune controls the
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,
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.
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
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
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
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
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
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
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.
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
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,
Titan (or Saturn VI) is the largest moon of Saturn. It is the only natural satellite known to have a dense atmosphere, and the only object other than Earth for which clear evidence of stable bodies of surface liquid has been found.
Titan is the sixth ellipsoidal moon from Saturn. Frequently described as a planet-like moon, Titan has a diameter roughly 50% larger than Earth's moon and is 80% more massive. It is the second-largest moon in the Solar System, after Jupiter's moon Ganymede, and it is larger by volume than the smallest planet, Mercury, although only half as massive. Titan was the first known moon of Saturn, discovered in 1655 by the Dutch astronomer Christiaan Huygens, and was the fifth moon of a planet apart from the Earth to be discovered.
Titan is primarily composed of water ice and rocky material. Much as with Venus prior to the Space Age, the dense, opaque atmosphere prevented understanding of Titan's surface until new information accumulated with the arrival of the Cassini–Huygens mission in 2004, including the discovery of liquid hydrocarbon lakes in the satellite's polar regions. The surface is geologically young; although mountains and several possible
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
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.
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.
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
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.
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
C/2007 E2 (Lovejoy) is a non-periodic comet discovered by Terry Lovejoy on 15 March 2007. Perihelion was 27 March 2007.
Perigee was 25 April 2007 in Hercules at a distance of 0.44 AU. Maximum apparent magnitude was approximately +8.
The discovery was made using a model 350D Canon consumer grade digital camera, and not a CCD survey camera.
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
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.
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.
Comet Lulin (official designation C/2007 N3 (Lulin), Traditional Chinese:鹿林彗星) is a non-periodic comet. It was discovered by Ye Quanzhi and Lin Chi-Sheng from Lulin Observatory. It peaked in brightness and arrived at perigee for observers on Earth on February 24, 2009, at magnitude +5, and at 0.411 AU from Earth. The comet was near conjunction with Saturn on February 23, and passed near Regulus in the constellation of Leo on February 26 and 27, 2009. It was expected to pass near Comet Cardinal on May 12, 2009. The comet became visible to the naked eye from dark-sky sites around February 7. It passed near the double star Zubenelgenubi on February 6, near Spica on February 15 and 16, near Gamma Virginis on February 19 and near the star cluster M44 on March 5 and 6. It also passed near the planetary nebula NGC 2392 on March 14, and near the double star Wasat around March 17. According to NASA, Comet Lulin's green color comes from a combination of gases that make up its local atmosphere, primarily diatomic carbon, which appears as a green glow when illuminated by sunlight in the vacuum of space.
The comet was first photographed by astronomer Lin Chi-Sheng (林啟生) with a 0.41-metre
Makemake, formally designated (136472) Makemake, is a dwarf planet and perhaps the largest Kuiper belt object (KBO) in the classical population, with a diameter that is probably about 2/3 the size of Pluto. Makemake has no known satellites, which makes it unique among the largest KBOs and means that its mass can only be estimated. Its extremely low average temperature, about 30 K (−243.2 °C), means its surface is covered with methane, ethane, and possibly nitrogen ices.
Initially known as 2005 FY9 and later given the minor planet number 136472, it was discovered on March 31, 2005, by a team led by Michael Brown, and announced on July 29, 2005. Its name derives from the Rapanui god Makemake. On June 11, 2008, the International Astronomical Union (IAU) included Makemake in its list of potential candidates to be given "plutoid" status, a term for dwarf planets beyond the orbit of Neptune that would place the object alongside Pluto, Haumea and Eris. Makemake was formally classified as a plutoid in July 2008.
Makemake was discovered on March 31, 2005, by a team at the Palomar Observatory, led by Michael Brown, and was announced to the public on July 29, 2005. The discovery of Eris was
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
The asteroid 12374 Rakhat is a Main belt asteroid discovered by Charles de Saint-Aignan at Lowell Observatory, examining films taken at Palomar.
Rakhat is a planet with the first known extraterrestrial life in the novel The Sparrow, by Mary Doria Russell. First contact is established when a group of specialists organized by Jesuits is sent to the planet. †.
This orbital diagram is courtesy of the JPL Small-Body Database Browser
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.
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.
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
Mars is the fourth planet from the Sun and the second smallest planet in the Solar System. Named after the Roman god of war, it is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a terrestrial planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the volcanoes, valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, as is the tilt that produces the seasons. Mars is the site of Olympus Mons, the highest known mountain within the Solar System, and of Valles Marineris, one of the largest canyons. The smooth Borealis basin in the northern hemisphere covers 40% of the planet and may be a giant impact feature. Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Martian trojan asteroid.
Until the first successful flyby of Mars occurred in 1965 by Mariner 4, many speculated about the presence of liquid water on the planet's surface. This was based on observed periodic variations in light and dark
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
Ganymede /ˈɡænɨmiːd/ (Jupiter III) is a satellite of Jupiter and the largest moon in the Solar System. It is the seventh moon and third Galilean satellite outward from Jupiter. Completing an orbit in roughly seven days, Ganymede participates in a 1:2:4 orbital resonance with the moons Europa and Io, respectively. It has a diameter of 5,268 km (3,273 mi), 8% larger than that of the planet Mercury, but has only 45% of the latter's mass. Its diameter is 2% larger than that of Titan, the second largest moon. It also has the highest mass of all planetary satellites, with 2.02 times the mass of the Earth's moon.
Ganymede is composed of approximately equal amounts of silicate rock and water ice. It is a fully differentiated body with an iron-rich, liquid core. A saltwater ocean is believed to exist nearly 200 km below Ganymede's surface, sandwiched between layers of ice. Its surface is composed of two main types of terrain. Dark regions, saturated with impact craters and dated to four billion years ago, cover about a third of the satellite. Lighter regions, crosscut by extensive grooves and ridges and only slightly less ancient, cover the remainder. The cause of the light terrain's
(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.
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.
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
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.
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
Europa /jʊˈroʊpə/ (Jupiter II), is the sixth closest moon of the planet Jupiter, and the smallest of its four Galilean satellites, but still one of the largest moons in the Solar system. Europa was discovered in 1610 by Galileo Galilei and possibly independently by Simon Marius around the same time. Progressively more in-depth observation of Europa has occurred over the centuries by Earth-bound telescopes, and by space probe flybys starting in the 1970s.
Slightly smaller than Earth's Moon, Europa is primarily made of silicate rock and probably has an iron core. It has a tenuous atmosphere composed primarily of oxygen. Its surface is composed of water ice and is one of the smoothest in the Solar System. This surface is striated by cracks and streaks, while cratering is relatively infrequent. The apparent youth and smoothness of the surface have led to the hypothesis that a water ocean exists beneath it, which could conceivably serve as an abode for extraterrestrial life. This hypothesis proposes that heat energy from tidal flexing causes the ocean to remain liquid and drives geological activity similar to plate tectonics.
The Galileo mission, launched in 1989, provided the bulk of
Mercury is the innermost planet in the Solar System. It is also the smallest, and its orbit is the most eccentric (that is, the least perfectly circular) of the eight planets. It orbits the Sun once in about 88 Earth days, completing three rotations about its axis for every two orbits. The planet is named after the Roman god Mercury, the messenger to the gods.
Mercury's surface is heavily cratered and similar in appearance to Earth's Moon, indicating that it has been geologically inactive for billions of years. Due to its near lack of an atmosphere to retain heat, Mercury's surface experiences the steepest temperature gradient of all the planets, ranging from a very cold 100 K at night to a very hot 700 K during the day. Mercury's axis has the smallest tilt of any of the Solar System's planets, meaning that there are no seasons on its surface. Mercury and Venus can each make appearances in Earth's sky both as a morning star and an evening star (because they are closer to the Sun than the Earth), and at times Mercury can technically be regarded as a very bright object when viewed from Earth; however, its proximity in the sky to the Sun makes it more difficult to see than
(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,
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.
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.
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.
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,
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°,
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.
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.
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 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
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
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.
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.
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.
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.
C/2001 Q4 (NEAT) is a comet with an unusual, almost perpendicular retrograde orbit which brings it into the inner solar system by a deeply southward path. It initially emerged from its remote home spending most of its time near the south celestial pole. This comet was discovered on August 24, 2001 by the Near-Earth Asteroid Tracking program (NEAT).
In 2004, residents of the southern hemisphere had the opportunity to watch the comet gradually brighten as it raced toward perihelion. On May 6, 2004 the comet approached within 0.32 AU of the Earth. Beginning in early May, the comet started racing north and burst into view in the northern hemisphere when it had reached almost maximum brightness.
With a near perihelion orbital eccentricity of 1.00069 (epoch 2004-May-18) that keeps a barycentric epoch 2014-Jan-01 eccentricity of 1.00067, this hyperbolic comet is going to be ejected from the Solar System.
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,
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.
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,
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
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,
Triton is the largest moon of the planet Neptune, discovered on October 10, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, which is an orbit in the opposite direction to its planet's rotation. At 2,700 km in diameter, it is the seventh-largest moon in the Solar System. Because of its retrograde orbit and composition similar to Pluto's, Triton is thought to have been captured from the Kuiper belt. Triton has a surface of mostly frozen nitrogen, a mostly water ice crust, an icy mantle and a substantial core of rock and metal. The core makes up two-thirds of its total mass. Triton has a mean density of 2.061 grams per cubic centimetre (0.0745 lb/cu in) and is composed of approximately 15–35% water ice.
Triton is one of the few moons in the Solar System known to be geologically active. As a consequence, its surface is relatively young, with a complex geological history revealed in intricate and mysterious cryovolcanic and tectonic terrains. Part of its crust is dotted with geysers thought to erupt nitrogen. Triton has a tenuous nitrogen atmosphere less than 1/70,000 the pressure of Earth's atmosphere at sea level.