Animation of Earth’s First Discovered Trojan Asteroid

Astronomers have discovered Earth’s first trojan asteroid.  Trojan asteroids are asteroids which orbit in the path of another planet.  They are difficult to discover because they occupy a part of the sky where the Sun is.  However, this particular trojan was discovered because of its highly erratic orbit and thanks to the NASA’s WISE observatory.  Because of the erratic orbit, at times it gets far enough out from the Earth’s orbital path, away from where the Sun would be in the sky, to be detected via infrared.