Discovery date April 13, 2001 Alternative names MPO 30455 Discovered 13 April 2001 | MPC designation 2001 GO2 Minor planet category Apollo
NEO Asteroid group Apollo asteroid | |
Discovered by Lincoln Laboratory ETS (now LINEAR) Discovery site Socorro, New Mexico, USA Similar 2002 AA29, 2003 YN107, 54509 YORP, (419624) 2010 SO16, 2014 OL339 | ||
2001 GO2 is a small asteroid that is a near-Earth object, an Earth coorbital, and an Apollo asteroid.
Orbit
With an orbital period of 368.95 days, 2001 GO2 is in a near 1:1 orbital resonance with Earth, and also has about the same orbit around the Sun as Earth. Unlike most near-Earth asteroids that simply fly by when they approach Earth, the Earth catches up with this asteroid from behind so that the asteroid then pauses in the vicinity of Earth. While in the vicinity of Earth, the asteroid moves in a helical (corkscrew) pattern that resembles an orbit around the Earth, like the Earth has a new moon. But it is not really a moon, because the asteroid is not gravitationally bound to the Earth, and eventually the asteroid moves on away from Earth and continues its orbit around the Sun. 2001 GO2 was in this helical pattern from about 1997 to 2005, making the closest approach to Earth on 6 April 2001, and will not make another close approach until 2092.
The asteroid probably has a horseshoe orbit, but this has not been proven because the orbit was determined from only 5 days worth of observation. The Jupiter Tisserand invariant, used to distinguish different kinds of orbits, is 6.033.
Other asteroids that move in this helical pattern, some of which the Earth catches up with the asteroid, and others in which the asteroid catches up with Earth, are 2003 YN107, 2002 AA29, and (164207) 2004 GU9.