Trojan asteroid of the Earth

2010 TK7, trojan asteroid of the Earth

The first Trojan asteroid (see nota) of the Earth was discovered in October 2010 by NASA, it accompanied us for a very long time in our journey around the Sun. The Observatory Canada-France-Hawaii in April 2011 confirmed its "Trojan".
The release took place in July 2011 in Nature.
2010 TK7 oscillates around a privileged point, that of the Lagrange point L4 couple's Sun-Earth, that is 60° ahead of Earth in its orbit around the Sun.
Among the five Lagrange points, only L4 and L5 points are stable, which means that the material and dust tend to accumulate in these particular areas of the orbits of planets.
2010 TK7 can not collide with the Earth. Found in the couple Jupiter-Sun, hundreds of Trojan asteroids that have taken agglutinate.
It is also found in some couples Neptune and Mars-Sun-Sun. There are also objects in the system Trojans Saturn satellite of Saturn. Saturn-Tethys Trojans with a 2 Telesto and Calypso, respectively 29 and 26 km in diameter, the L4 and L5 points.
Saturn-Dione with Helen, a star of 33 km in diameter, to the point L4 and L5 Pollux point. But until 2010 no Trojan land had been discovered.
2010 TK7 is so small (a few 300 meters) and so far (about 80 million kilometers from Earth) it was difficult to see. In addition it is close to the Sun and often in its light. The asteroid is currently located about 80 million kilometers from Earth will be closest to Earth at 24 million miles in 100 years.

Video: Youtube video (requires flash player). The asteroid 2010TK7 ahead of Earth in its orbit around the Sun. TK7 is one year as the Earth to complete one revolution around the Sun, but it made the rotation spinning majestically in the area of Lagrangian L4. On the video, the area of Lagrangian point L4 is curious, influenced by both the Sun and Earth.

Image: 2010 TK7 (in the small green circle) was photographed for the first time in October 2010 by the Wide-field Infrared Survey Explorer at a program that was designed to photograph the entire sky.