|Discovered by||Johann Palisa|
|Discovery date||25 October 1888|
|MPC designation||(279) Thule|
|Pronunciation||/ / THEW-lee|
|1927 EC, 1954 FF, A920 GA, A923 RA|
|Asteroid belt (Thule)|
|Epoch 31 July 2016 (JD 2457600.5)|
|Uncertainty parameter 0|
|Observation arc||125.34 yr (45780 d)|
|Aphelion||4.4617880 AU (667.47398 Gm)|
|Perihelion||4.2367660 AU (633.81117 Gm)|
|4.3492770 AU (650.64258 Gm)|
|9.07 yr (3313.0 d)|
|0° 6m 31.184s / day|
|Dimensions||126.59±3.7 km (IRAS)|
|23.896 h (0.9957 d)|
Thule, minor planet designation: 279 Thule, is a large asteroid from the outer asteroid belt. It is classified as a D-type asteroid and is probably composed of organic-rich silicates, carbon and anhydrous silicates. Thule was the first asteroid discovered with a semi-major axis greater than 4 AU. It was discovered by Johann Palisa on 25 October 1888 in Vienna and was named aptly after the ultimate northern land of Thule.
A formal minor planet designation is, in its final form, a number–name combination given to a minor planet. Such designation always features a leading number assigned to a body once its orbital path is sufficiently secured. The formal designation is based on the minor planet's provisional designation, which was previously assigned automatically when it had been observed for the first time. Later on, the provisional part of the formal designation may be replaced with a name. Both formal and provisional designations are overseen by the Minor Planet Center (MPC), a branch of the International Astronomical Union.
Asteroids are minor planets, especially of the inner Solar System. Larger asteroids have also been called planetoids. These terms have historically been applied to any astronomical object orbiting the Sun that did not resemble a planet-like disc and was not observed to have characteristics of an active comet such as a tail. As minor planets in the outer Solar System were discovered they were typically found to have volatile-rich surfaces similar to comets. As a result, they were often distinguished from objects found in the main asteroid belt. In this article, the term "asteroid" refers to the minor planets of the inner Solar System including those co-orbital with Jupiter.
The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets. The asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids: Ceres, Vesta, Pallas, and Hygiea. The total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Pluto's moon Charon.
Thule was the first discovered member of the Thule dynamical group, which as of 2008 is known to consist of three objects: 279 Thule, (186024) 2001 QG207 , and (185290) 2006 UB219 . The orbits of these bodies are unusual. They orbit in the outermost edge of the asteroid belt in a 4:3 orbital resonance with Jupiter, the result of the periodic force Jupiter exerts on a body with Thule's orbital period, in the same way (though with the reverse effect) as the Kirkwood gaps in the more inner parts of the asteroid belt.
In celestial mechanics, orbital resonance occurs when orbiting bodies exert regular, periodic gravitational influence on each other, usually because their orbital periods are related by a ratio of small integers. Most commonly this relationship is found for a pair of objects. The physical principle behind orbital resonance is similar in concept to pushing a child on a swing, where the orbit and the swing both have a natural frequency, and the other body doing the "pushing" will act in periodic repetition to have a cumulative effect on the motion. Orbital resonances greatly enhance the mutual gravitational influence of the bodies, i.e., their ability to alter or constrain each other's orbits. In most cases, this results in an unstable interaction, in which the bodies exchange momentum and shift orbits until the resonance no longer exists. Under some circumstances, a resonant system can be stable and self-correcting, so that the bodies remain in resonance. Examples are the 1:2:4 resonance of Jupiter's moons Ganymede, Europa and Io, and the 2:3 resonance between Pluto and Neptune. Unstable resonances with Saturn's inner moons give rise to gaps in the rings of Saturn. The special case of 1:1 resonance between bodies with similar orbital radii causes large Solar System bodies to eject most other bodies sharing their orbits; this is part of the much more extensive process of clearing the neighbourhood, an effect that is used in the current definition of a planet.
Jupiter is the fifth planet from the Sun and the largest in the Solar System. It is a gas giant with a mass one-thousandth that of the Sun, but two-and-a-half times that of all the other planets in the Solar System combined. Jupiter has been known to astronomers since antiquity. It is named after the Roman god Jupiter. When viewed from Earth, Jupiter can be bright enough for its reflected light to cast shadows, and is on average the third-brightest natural object in the night sky after the Moon and Venus.
A Kirkwood gap is a gap or dip in the distribution of the semi-major axes of the orbits of main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter.
Freia is a very large main-belt asteroid. It orbits in the outer part of the asteroid belt and is classified as a Cybele asteroid. Its composition is very primitive and it is extremely dark in color. Freia was discovered by the astronomer Heinrich d'Arrest on October 21, 1862, in Copenhagen, Denmark. It was his first and only asteroid discovery. It is named after the goddess Freyja in Norse mythology.
Semele is a large and very dark main-belt asteroid. It is probably composed of carbonates. Semele was discovered by German astronomer Friedrich Tietjen on January 4, 1866. It was his first and only asteroid discovery. It is named after Semele, the mother of Dionysus in Greek mythology.
Hekate is a large main-belt asteroid. It orbits in the same region of space as the Hygiea asteroid family, though it is actually an unrelated interloper. Its albedo of 0.19 is too high, and it is of the wrong spectral class to be part of the dark carbonaceous Hygiea family. It is listed as a member of the Hecuba group of asteroids that orbit near the 2:1 mean-motion resonance with Jupiter.
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 2 November 1875, from the Austrian Naval Observatory at Pula, now Croatia. The name was chosen by the astronomer Theodor von Oppolzer, who named it after one of his daughters.
Ismene is a very large main belt asteroid. It was discovered by German-American astronomer C. H. F. Peters on September 22, 1878, in Clinton, New York, and named after Ismene, the sister of Antigone in Greek mythology.
Chryseïs is a large, lightly coloured Main belt asteroid that is probably composed of silicate rocks. It was discovered by C. H. F. Peters on September 11, 1879, in Clinton, New York, and was named after the mythical Trojan woman Chryseis.
Adelinda is a large, dark outer main-belt asteroid. It was discovered by Austrian astronomer Johann Palisa on August 22, 1882, in Vienna, and was named after Adelinda, the wife of fellow Austrian astronomer Edmund Weiss.
Huberta is a large asteroid orbiting near the outer edge of the Main belt. It is dark and rich in carbon.
Lacadiera is a large Main belt asteroid. It is classified as a D-type asteroid and is probably composed of organic rich silicates, carbon and anhydrous silicates. The asteroid was discovered by Auguste Charlois on 19 September 1892 in Nice.
Bononia is a very large main-belt asteroid. It is classified as a D-type asteroid and is probably composed of organic rich silicates, carbon and anhydrous silicates. It was discovered by Auguste Charlois on March 11, 1893, in Nice.
Helga, provisional designation 1904 NC is an asteroid orbiting the Sun discovered in 1904 by Max Wolf in Heidelberg. Helga is notable for being the first such object to be shown to be in a stable but chaotic orbit in resonance with Jupiter, its Lyapunov time being relatively short, at 6,900 yr. Despite this, its orbit appears to be stable, as the eccentricity and precession rates are such that it avoids close encounters with Jupiter.
668 Dora is an asteroid orbiting in the asteroid belt located roughly between the orbits of the planets Mars and Jupiter.
677 Aaltje is a main-belt minor planet orbiting the Sun, discovered by August Kopff at Heidelberg on January 18, 1909. It was named after the Dutch singer Aaltje Noordewier-Reddingius.
887 Alinda is a very eccentric, near-Earth asteroid with an Earth minimum orbit intersection distance (MOID) of 0.092 AU. It is the namesake for the Alinda group of asteroids and measures about 4 kilometers in diameter. The stony S-type asteroid was discovered by German astronomer Max Wolf at Heidelberg Observatory on 3 January 1918.
11665 Dirichlet, provisional designation 1997 GL28, is a Griqua asteroid and a 2:1 Jupiter librator from the outermost regions of the asteroid belt, approximately 6.8 kilometers (4 miles) in diameter. It was discovered on 14 April 1997, by astronomer Paul Comba at the Prescott Observatory in Arizona, United States. The asteroid was named after German mathematician Peter Gustav Lejeune Dirichlet.
9767 Midsomer Norton is an outer main-belt asteroid discovered on March 10, 1992, by Duncan Steel at Siding Spring. It is one of very few asteroids located in the 2 : 1 mean motion resonance with Jupiter.
1921 Pala, provisional designation 1973 SE is an unstable asteroid from the background population of the outer asteroid belt, approximately 8.2 kilometers in diameter. It is one of very few bodies located in the 2 : 1 mean motion resonance with Jupiter. It was discovered by Dutch–American astronomer Tom Gehrels at Palomar Observatory on 20 September 1973.
8373 Stephengould is an outer main-belt binary asteroid discovered on January 1, 1992, by Carolyn S. Shoemaker and Eugene Merle Shoemaker at Palomar Observatory. The asteroid was named after the Harvard paleontologist Stephen Jay Gould. The asteroid has a very high inclination, having the second highest inclination of any of the first 10,000 discovered asteroids in the asteroid belt, after 2938 Hopi.
5201 Ferraz-Mello is an asteroid from the asteroid belt, discovered on December 1, 1983, by Ted Bowell at the Anderson Mesa Station of the Lowell Observatory. It is one of very few Hecuba-gap asteroid located in the 2 : 1 mean motion resonance with Jupiter.
6144 Kondojiro (1994 EQ3) is an asteroid discovered on March 14, 1994 by Kin Endate and Kazuro Watanabe at the Kitami Observatory in eastern Hokkaidō, Japan. It is named after Jiro Kondo, a Japanese Egyptologist and professor of archaeology at Waseda University.
The JPL Small-Body Database (SBDB) is an astronomy database about small Solar System bodies. It is maintained by Jet Propulsion Laboratory (JPL) and NASA and provides data for all known asteroids and several comets, including orbital parameters and diagrams, physical diagrams, and lists of publications related to the small body. The database is updated on a daily basis.
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