Damocloids are a class of minor planets such as 5335 Damocles and 1996 PW that have Halley-type or long-period highly eccentric orbits typical of periodic comets such as Halley's Comet, but without showing a cometary coma or tail. David Jewitt defines a damocloid as an object with a Jupiter Tisserand invariant (TJ) of 2 or less, while Akimasa Nakamura defines this group with the following orbital elements:
(65407) 2002 RP120, provisional designation 2002 RP120, is a trans-Neptunian object and damocloid from the outer Solar System. Its orbit is retrograde and comet-like, and has a high eccentricity. It was discovered on 4 September 2002 by astronomers with the LONEOS survey at Anderson Mesa Station, Arizona, in the United States. The unusual object measures approximately 14.6 kilometers (9.1 miles) in diameter and is likely elongated in shape. It is a slow rotator and potentially a tumbler as well. The object was probably ejected from the ecliptic by Neptune.
20461 Dioretsa is a centaur and damocloid on a retrograde, cometary-like orbit from the outer Solar System. It was discovered on 8 June 1999, by members of the LINEAR team at the Lincoln Laboratory Experimental Test Site near Socorro, New Mexico, United States. The highly eccentric unusual object measures approximately 14 kilometers in diameter. It was named Dioretsa, the word "asteroid" spelled backwards.
(5335) Damocles, provisional designation 1991 DA, is a centaur and the namesake of the damocloids, a group of minor planets which may be inactive nuclei of the Halley-type and long-period comets. It was discovered on 18 February 1991, by Australian astronomer Robert McNaught at Siding Spring Observatory in Australia. It is named after Damocles, a figure of Greek mythology.
20898 Fountainhills, provisional designation 2000 WE147, is a dark asteroid in a cometary orbit (ACO) from the outermost regions of the asteroid belt, approximately 37 kilometers (23 miles) in diameter. It was discovered on 30 November 2000, by American amateur astronomer Charles W. Juels at the Fountain Hills Observatory in Arizona, United States. The D-type asteroid has a rotation period of 12.84 hours. It was named for the city of Fountain Hills, Arizona, in the United States.
(612093) 1999 LE31, prov. designation: 1999 LE31, is a centaur and damocloid on a retrograde and eccentric orbit from the outer region of the Solar System. It was first observed on 12 June 1999, by astronomers with the LINEAR program at the Lincoln Lab's ETS near Socorro, New Mexico, in the United States. The unusual object measures approximately 17 kilometers (11 miles) in diameter.
2010 EU65 is a centaur, approximately 64 kilometers (40 miles) in diameter, orbiting the Sun in the outer Solar System. The object is also a promising Uranus horseshoe librator candidate. It was first observed on 13 March 2010, by American astronomers David Rabinowitz and Suzanne Tourtellotte, observing from Cerro Tololo and La Silla Observatory in Chile. As of 2021, it has neither been numbered nor named.
2005 VX3 is trans-Neptunian object and retrograde damocloid on a highly eccentric, cometary-like orbit. It was first observed on 1 November 2005, by astronomers with the Mount Lemmon Survey at the Mount Lemmon Observatory in Arizona, United States. The unusual object measures approximately 7 kilometers (4 miles) in diameter. It has the 3rd largest known heliocentric semi-major axis and aphelion. Additionally its perihelion lies within the orbit of Jupiter, which means it also has the largest orbital eccentricity of any known minor planet.
2013 LA2 is a centaur and damocloid on a cometary-like and retrograde orbit from the outer Solar System, suggesting that it is an extinct comet. It was first observed on 1 June 2013 by astronomers with the Pan-STARRS survey at Haleakala Observatory, Hawaii, in the United States. The object measures approximately 1.8 kilometers (1.1 miles) in diameter. It holds the record for having the highest orbital inclination of any known minor planet.
(336756) 2010 NV1, prov. designation: 2010 NV1, is a highly eccentric planet crossing trans-Neptunian object, also classified as centaur and damocloid, approximately 52 kilometers (32 miles) in diameter. It is on a retrograde cometary orbit. It has a barycentric semi-major axis (average distance from the Sun) of approximately 286 AU.
(523719) 2014 LM28, provisional designation 2014 LM28, is a trans-Neptunian object and centaur, approximately 46 kilometers (29 miles) in diameter. It was discovered on 16 May 2013, by the Pan-STARRS 1 survey at Haleakala Observatory, Hawaii, United States. The object's orbit is highly inclined and very eccentric, with a perihelion closer to the Sun than Uranus and at an aphelion 17 times farther from the Sun than Neptune.
(127546) 2002 XU93, provisional designation 2002 XU93, is a trans-Neptunian object and centaur on highly inclined and eccentric orbit in the outer region of the Solar System. It measures approximately 170 kilometers (110 mi) in diameter and is one of few objects with such an unusual orbit. It was discovered on 4 December 2002, by American astronomer Marc Buie at the Kitt Peak National Observatory in Arizona, United States.
(606357) 2017 UV43 is a centaur from the outer Solar System, approximately 8 kilometers (5 miles) in diameter. It was discovered by the Mount Lemmon Survey on 13 March 2005. The unusual minor planet follows an orbit similar to those of the fragments of comet Shoemaker–Levy 9. This minor planet was numbered (606357) by the Minor Planet Center on 27 October 2021 (M.P.C. 136418). As of November 2021, it has not yet been named.
(342842) 2008 YB3, provisional designation: 2008 YB3, is a sizable centaur and retrograde damocloid from the outer Solar System, approximately 67 kilometers (42 miles) in diameter. It was discovered on 18 December 2008, by astronomers with the Siding Spring Survey at the Siding Spring Observatory in Australia. The minor planet was numbered in 2012 and has since not been named.
(468861) 2013 LU28, provisional designation 2013 LU28 is a highly eccentric trans-Neptunian object, retrograde centaur and damocloid from the outer regions of the Solar System. It was discovered on 8 June 2013 by astronomers with the Mount Lemmon Survey at the Mount Lemmon Observatory in Arizona, United States. The object is unlikely a dwarf planet as it measures approximately 110 kilometers (68 miles) in diameter. It was numbered in 2016 and has not been named since.
In planetary science, the term unusual minor planet, or unusual object, is used for a minor planet that possesses an unusual physical or orbital characteristic. For the Minor Planet Center (MPC), which operates under the auspices of the International Astronomical Union, any non-classical main-belt asteroid, which account for the vast majority of all minor planets, is an unusual minor planet. These include the near-Earth objects and Trojans as well as the distant minor planets such as centaurs and trans-Neptunian objects. In a narrower sense, the term is used for a group of bodies – including main-belt asteroids, Mars-crossers, centaurs and otherwise non-classifiable minor planets – that show a high orbital eccentricity, typically above 0.5 and/or a perihelion of less than 6 AU. Similarly, an unusual asteroid (UA) is an inner Solar System object with a high eccentricity and/or inclination but with a perihelion larger than 1.3 AU, which does exclude the near-Earth objects.
2006 LM1 is a trans-Neptunian object and retrograde damocloid on a highly eccentric, cometary-like orbit. It was first observed on 3 June 2006 by the Mount Lemmon Survey at the Mount Lemmon Observatory in Arizona, United States. The orbit of 2006 LM1 is highly uncertain as its observation arc is only spans 2 days. 2006 LM1 measures approximately 5 kilometers (3 miles) in diameter, assuming a low albedo of 0.09.
(523676) 2013 UL10 (prov. designation:2013 UL10) is a reddish centaur with cometary activity orbiting the Sun between Jupiter and Uranus. It was discovered on 18 August 2010, by a team of astronomers with the Pan-STARRS survey at the Haleakalā Observatory, Hawaii. It is the first centaur known to have both comet-like activity and red surface colors. It is also one of the smallest centaurs, with a nucleus of no more than 10 kilometers (6.2 miles) in diameter. As of 2021, it has not been named.
2017 SV13 is a centaur and damocloid on a retrograde and highly eccentric orbit from the outer region of the Solar System. It was first observed on 17 September 2017 by the Pan-STARRS survey at Haleakala Observatory in Hawaii, United States. This unusual object measures approximately 1 kilometer (0.6 miles) in diameter.
