NASA: Earth shares its orbit with Trojan asteroid (photos)

NASA announced that it has discovered that Earth is sharing its orbit with an asteroid as they both circle the sun. This "Trojan" asteroid called 2010 TK7 is about 1,000 meters in diameter and is about 50 million miles away. Scientists say that it's not a threat - it won't come any closer than 15 million miles in the next 100 years. Here's an animation showing the orbits of the Earth and its asteroid.

The discovery was made by NASA's NEO Observation Program which it funded to process data from the Wide-field Infrared Survey Explorer (WISE) mission. NEOWISE studies near-Earth objects (NEO) such as asteroids.

Scientists had believed that there were Trojan asteroids within Earth's orbit but they were too small and appeared near the sun from the Earth's point of view until now.
Image credit: Paul Wiegert, University of Western Ontario, Canada

Trojan asteroid 2010 TK7 is circled in green in this image. Most of the other dots are stars and galaxies well outside our solar system.

Trojan asteroids share orbits with Neptune, Mars and Jupiter as well as two of Saturn's moons.

"It's as though Earth is playing follow the leader," said Amy Mainzer, the principal investigator of NEOWISE at NASA's Jet Propulsion Laboratory in Pasadena, Calif. "Earth always is chasing this asteroid around."

Image credit: NASA/JPL-Caltech/UCLA

In news from Earth, NASA announces a new app, Visualization Explorere for the iPad. According to NASA: "this new, free app presents Earth as you've never seen it before; travel to places otherwise unavailable to even the most intrepid explorers!"