'Double planet' found

Astronomers say a pair of small rocks orbiting each other at the edge of the solar system may be planets.

But the lumps of rock and ice are only a few hundred miles in diameter and other experts say they are too small to be planets.

The pair are in the Kuiper Belt, a group of at least 70,000 objects which circle the Sun beyond Pluto.

Astronomers knew there was some kind of unusual object in there and called it "1998 WW 31" but they didn't know it was a twin.

The observations were made from the Canada-France-Hawaii Telescope, according to reports.