Match made in heaven: Earth finds new companion as giant asteroid joins its path around the sun - 6th Apr 2011

Earth has found a new companion that has joined its orbit around the sun, scientists have revealed.

It may not have the most romantic of names, but Asteroid 2010 SO16 could pursue Earth for anywhere between the next 120,000 to a million years.

And at a few hundred metres across, it is the largest space rock ever discovered so close to earth.

But there is something unusual about SO16, say Apostolos Christou and David Asher who discovered the giant floating rock last September at the Armagh Observatory in Northern Ireland.

Rather than follow its new friend all the way round, SO16 orbits the sun in a horseshoe shape, playing a constant game of catch up with Earth, they say.

The closer to the sun an object is, the faster it will orbit.

So when SO16 entered the sun's orbit, it was further away than Earth and therefore slower.

When Earth finally caught up with the asteroid, instead of overtaking it, its gravitational pull drew it closer to the sun sending it back round at a faster pace. Read More