Asteroid Discovered in Earth Orbit

An infrared study of our local sky has revealed that we are not alone in an orbit – an asteroid is traveling with us.

They are called Trojan asteroids, and several of the major planets have them. They are asteroids that orbit the sun in the same path as the planet.

Ours is only 1,000 feet across – a tiny speck of rock slowly tumbling in space. The Trojan’s orbit describes a wild, tumbling arc around the sun. But that orbit lies on the same plane and about the same distance from the sun as our own.

What makes this asteroid a Trojan is that it has fallen into a stable, if wild, orbit. It travels its circle around the sun at almost the same speed as Earth, so that its position relative to us is always the same. It is as if Earth is playing a forever game of follow the leader.

The chances of crashing into the asteroid are startlingly slim. Right now the Trojan is about 50 million miles ahead of us in our orbit. It’s tumbling around the orbital path may bring us closer. In fact, it’s estimated that the closest is should get to us is 15 million miles – that’s a pretty safe distance.

Before you settle back in your easy chair, however, you should know that the Trojan was picked out of a survey of near Earth objects (NEOs) by the WISE infrared satellite. WISE surveyed the entire sky for over a year and turned up over 500 NEO’s, nearly a quarter of which were previously unknown. An NEO is described as an object that passes within 28 million miles of our orbit around the sun.

So far we’ve identified just the one Trojan asteroid. It is theorized that there is probably another one, occupying the same location in the opposite direction. Although our Trojan poses no threat to us, it is interesting to know that we are not alone in our orbital path.

You can learn more about WISE and the hunt for Trojans at NASA’s WISE page.