spacetoday.net: First Earth Trojan asteroid discovered

Posted: Thu, Jul 28, 2011, 9:36 AM ET (1336 GMT)
Earth Trojan asteroid Illustration (NASA/JPL)

Astronomers sifting through data from a NASA satellite have discovered the first "Trojan" asteroid sharing the same general orbit as the Earth. Astronomers found the asteroid, 2010 TK7, in observations by NASA's Wide-field Infrared Survey Explorer (WISE) spacecraft, and confirmed its orbit in later observations by the Canada-France-Hawaii Telescope on Mauna Kea, Hawaii. The asteroid, about 300 meters across, is in roughly the same orbit as the Earth, but ahead of it; it is about 80 million kilometers from Earth but has a complex trajectory that at times can bring it to within 24 million kilometers. This is the first so-called Trojan asteroid found associated with Earth, although Trojan asteroids have been found in the orbits of several other planets, most notably Jupiter, leading and trailing the planets by 60 degrees.