Violent 'weather forecast' for 'failed stars'

The first weather forecast for a brown dwarf is in - and it's not looking good up there.

Astronomers predict it will rain molten iron and "snow" hot sand, with lightning and hurricanes likely.

New observations with Nasa's Spitzer telescope reveal surprisingly turbulent storm clouds circling these "failed stars".

The weather report was given at the 223rd meeting of the American Astronomical Society in Washington DC.

It is the most detailed ever for a world outside our Solar System.

"So let's all sing the forecast for our nearest brown dwarf: Let it snow (rocks) let it snow (sand) let it snow (gems)," said Prof Adam Burgasser of the University of California.

Brown dwarfs are "failed stars" which lack the mass to keep fusing atoms and blossom into fully-fledged suns.

They were known to be hot and hostile. But when astronomers pointed Spitzer at 44 different brown dwarfs, they were surprised to find almost half showed clear evidence of weather - dynamic storm systems with unpredictable patterns.

"This is not like Jupiter's Great Red Spot. The storms on brown dwarfs are much more violent and variable. This is weather, not climate," says Dr Aren Heinze, of Stony Brook University, New York.

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