Discovered by Kitt Peak (695) MPC designation (42301) 2001 UR163 Aphelion 65.876 AU (9.8549 Tm) Inclination 0.75238° Orbits Sun | Discovery date 21 October 2001 Observation arc 9591 days (26.26 yr) Discovered 21 October 2001 Argument of perihelion 342.203° Discoverer Deep Ecliptic Survey | |
Minor planet category TNO (SDO)
4:9 resonance Discovery site Kitt Peak National Observatory Similar (84922) 2003 VS2, 2008 ST291, (119951) 2002 KX14 | ||
(42301) 2001 UR163, also written as (42301) 2001 UR163, is likely a dwarf planet that resides in the scattered disc. It was discovered on October 21, 2001 by the Deep Ecliptic Survey (DES) program at Kitt Peak. Light-curve-amplitude analysis shows only small deviations, suggesting that (42301) 2001 UR163 is a spheroid with small albedo spots. Michael Brown's website lists it as a highly likely dwarf planet, but the diameter of the object has never been measured.
(42301) 2001 UR163 has the reddest color index of any object in the Solar System. On October 31, 2002, the 3.6-meter Canada–France–Hawaii Telescope observed (42301) 2001 UR163 set a record red reading of B−R=2.28. This makes (42301) 2001 UR163 even redder than Pholus, (119070) 2001 KP77, Sedna and comet C/2001 T4.
Reddening of the spectrum is caused by cosmic irradiation by ultraviolet radiation and charged particles. Becoming bluer in the spectrum is caused by impact collisions exposing the interior of an object. In the visible spectrum, (42301) 2001 UR163 would appear orange-brown, depending on its albedo.
It came to perihelion around 1937. In 2006, it moved beyond 50 AU from the Sun. It is currently 51.9 AU from the Sun.