Trojan Asteroid Shares Orbit With Earth

NASA Jet Propulsion Laboratory California Institute of Technology

The elliptical path, along, the Earth's path around the sun, makes me think that it could be a former satellite of Earth, that impacted with our only moon, and was thrown off of the Earth's gravitational pull, but was unable to escape that of the sun. It continues to rotate around an object that does not exist, or one that has abandoned it.

Imagine that a wheel has come off of your car while traveling down the road. The car and the wheel may still travel along the same path, but are no longer connected.

http://www.jpl.nasa.gov/video/index.cfm?id=1007