7:45am UK, Friday October 25, 2002

Scientists have discovered a planet one billion miles beyond Pluto.

They say it is the most significant find in our solar system in more than 70 years.

180 drawing quaoar largest object orbiting sun

A pinprick of light from the icy planet-like object was spotted by two scientists.

They namedthe distant planet Quaoar, pronounced Kwah-o-ar, after an ancient American tribe.

It is the largest spherical object to be found in our solar system since the discovery of Pluto in 1930.

Dr Mike Brown and Chad Trujillo, of the California Institute of Technology, first caught sight of Quaoar through a 48in telescope.

Earth link

Quaoar is four billion miles from planet Earth and takes 288 years to orbit the sun.

It is immediately north-west of the constellation Scorpio.

Amateur astronomers should be able to pick it up with a 16in telescope.

Quaoar sits in the Kuiper belt, where comets originate.

Scientists hope the discovery might provide vital clues about the formation of the Earth five-billion years ago.