Discovered by Catalina Sky Survey MPC designation 2015 YA Aphelion 1.27598 AU | Discovery date December 16, 2015 Observation arc 5 days | |
 | ||
2015 YA (also written 2015 YA) is an Aten asteroid that is a temporary horseshoe companion to the Earth, the eleventh known Earth horseshoe librator. Prior to a close encounter with the Earth on 2015 December 15 2015 YA was an Apollo asteroid.
Contents
Discovery
2015 YA was discovered on 2015 December 16 G. J. Leonard and R. G. Matheny observing for the Catalina Sky Survey. As of 9 March 2016, it has been observed 47 times with an observation arc of 5 days.
Orbit and orbital evolution
2015 YA is currently an Aten asteroid (Earth-crossing but with a period less than a year). Its semi-major axis (currently 0.99753 AU) is similar to that of Earth (1.00074 AU), but it has a moderate eccentricity (0.2791) and very low orbital inclination (1.6249°). It alternates between being an Aten asteroid and being an Apollo asteroid, although its orbital evolution is rather chaotic. As of 9 March 2016, this object is the 16th known Earth co-orbital and the 11th known object following a horseshoe path with respect to our planet. Asteroid 2015 YA follows an asymmetrical horseshoe path with respect to our planet; the value of its relative mean longitude oscillates about 180°, but enclosing 0°.
Physical properties
With an absolute magnitude of 27.4 mag, it has a diameter in the range 9–22 meters (for an assumed albedo range of 0.04–0.20, respectively).