# 2010 SO16

2010 SO16
Discovery
Discovered by Wide-field Infrared Survey Explorer
Orbital characteristics[1]
Epoch January 4, 2010 (2455200.5)
Aphelion 1.058 AU (Q)
Semi-major axis 1.00039 AU (a)
Eccentricity 0.075188
Mean anomaly 137.831° (M)
Inclination 14.536°
Longitude of ascending node 40.523°
Argument of perihelion 108.283°
Physical characteristics
Dimensions 200–400 metres
Absolute magnitude (H) 20.7

2010 SO16 is a near-Earth asteroid discovered by the Wide-field Infrared Survey Explorer space telescope. The orbit was described by Christou Apostolos and David Asher at the Armagh Observatory in Northern Ireland.[1] The object has a magnitude of 20.7 and is several hundred meters in diameter.

2010 SO16 has a "horseshoe orbit" that allows it to stably share Earth's orbital neighborhood without colliding with it. It is one of a handful of known asteroids with such an orbit, a group that includes 3753 Cruithne. It is, however, neither an Aten asteroid nor an Apollo asteroid because the semi-major axis of its orbit is neither less than nor greater than 1 AU, but oscillates between approximately 0.996 and 1.004 AU, with a period of about 350 yr.[1] In its ~350 yr horseshoe cycle, it never approaches the Earth more closely than about 0.15 AU, alternately trailing and leading.

According to various simulations 2010 SO16 will remain in this orbit for at least 120,000 years and possibly for more than a million years, which is unusually stable compared to other similar objects.[2] One reason for this stability is its low orbital eccentricity, $< 0.084$.[1]