LONDON: Astronomers have captured a vision of the cataclysmic fate which awaits our solar system in about five billion years. Observation of a star system some 450 million light years from earth has revealed all that remains of a planetary system located around a star that was once eight times the size of the sun.

Scientists have discovered a lonely dwarf star orbited by a small ring of metallic gas. The white dwarf is now a hundred times smaller than our sun, burning with a surface temperature 22,000 degrees C. "It's giving a glimpse of our future," said a physicist at the University of Warwick.

The same fate awaits the sun. As its hydrogen fuel runs out the sun will eventually swell to 200 times its present size. At this stage it will destroy Mercury and Venus, and push the remaining planets out. The sun will contract into the smaller, more dense, white dwarf.

In five to eight billion years, when the sun becomes a white dwarf, there will be no inner planets left. Asteroids, however, could be knocked towards the star by large planets, such as Jupiter.

White dwarfs often exist by themselves in the galaxy and are often orbited by clouds of gas. What makes the new discovery rare is that its disc of gas contains no hydrogen or helium, the two gases that make up more than 99 per cent of the universe. The only elements scientists spotted were calcium, iron and magnesium.

© Guardian Newspapers Limited 2006

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