Asteroid 2002 AA29

Asteroid 2002 AA29 is an asteroid that is in a 1:1 resonance with the Earth. Such asteroids are often refered to as co-orbital with the Earth. It spends much of its time in a horseshoe orbit. But every few hundred years, it leaves its horseshoe orbit and occupies the area normally avoided by its horseshoe orbit. During a period that lasts a few decades, asteroid 2002 AA29 never strays far from the Earth as it circles the Earth/Moon system in a quasi-orbit. Eventually, it will leave this configuration and exit the Earth system from the same direction it entered.

The simulations listed below show this asteroid in a rotating frame. The first simulation shows the asteroid approach Earth only to turn around when it gets too close. The second simulation shows the asteroid approach Earth and enter a quasi-orbit around the Earth/Moon system. the third simulation shows the asteroid in its solar orbit as it receeds from Earth in 2005. These simulations may be run with a time step as large as 4096 seconds.

Starting conditions were obtained using JPL Horizons Ephemeris Computation Service.

Download 2002aa29_1.gsim
Download 2002aa29_2.gsim
Download 2002aa29_3.gsim

(You need to have the program Gravity Simulator installed on your computer first. Click Here to download Gravity Simulator.)


Asteroid 2002 AA29 spends most of its time tracing a looping horseshoe orbit around the Sun. The Earth/Moon system traces a small oval in the horseshoe's gap.


Upon approaching Earth, asteroid 2002 AA29 is repeled. It reverses direction and heads back around the Sun in the other direction.


But sometimes asteroid 2002 AA29 advances beyond Earth's position and enters a quasi-orbit around the Earth/Moon system.


For the next 50 years, asteroid 2002 AA29 remains in its quasi-orbit. It finally escapes the Earth's vicinity in the same direction it entered. It will spend hundreds of years in a horseshoe orbit before it enters a quasi-orbit again.