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WE鈥橵E found planets around other stars, now we know some of them have water
too. And if other planetary systems have water, they may also harbour the other
ingredients for life.

Water has been detected before in the vicinity of other stars, but only young
stars surrounded by dusty discs of material which has yet to coalesce into
planets. But astronomers have always assumed that the water in such systems
comes from the stars which, being young, are rich in hydrogen.

Now NASA鈥檚 Submillimeter Wave Astronomy Satellite (SWAS) has found evidence
of water vapour around a red giant called CW Leonis. Because CW Leonis is old
and has burnt all its hydrogen, astronomers expected to find only a tiny amount
of water. But SWAS found 10,000 times the amount they predicted.

Gary Melnick from the Harvard-Smithsonian Center for Astrophysics in
Cambridge, Massachusetts, and his SWAS team believe the water must have come
from planets or comets that orbited the star. But as CW Leonis began to run out
of hydrogen fuel, it swelled up and engulfed its water-rich planetary system.
鈥淲e are witnessing the apocalypse that will befall our own Solar System,鈥� says
Melnick.