20461 Dioretsa

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20461 Dioretsa
Discovery and designation
Discovered by Lincoln Laboratory Near-Earth Asteroid Research Team at Socorro[1]
Discovery date 8 June 1999
MPC designation 20461
Pronunciation /d.əˈrɛtsə/ dy-ə-RET-sə
1999 LD31
Minor planet category centaur,[1] damocloid
Orbital characteristics[1]
Epoch 2455800.5 (2011 Aug 27.0)
Aphelion 45.151 AU
Perihelion 2.383173 AU
23.7672 AU
Eccentricity 0.899729
115.87 yr (42,322 days)
Inclination 160.4028° (retrograde)
Physical characteristics

Dioretsa (1999 LD31) is a centaur[1] discovered in 1999 notable for its unusual orbit, which is highly eccentric and retrograde. Its name is the word 'asteroid' spelled backwards to reflect this fact. It is one of twenty or so known minor planets in the Solar System that have a retrograde orbit—see the List of notable asteroids.

Dioretsa's orbit is otherwise similar to a comet's; it has a perihelion of 2.4 AU and an aphelion of 45.2 AU. This has led to speculation that Dioretsa was originally an object from the Oort cloud.