With improved techniques, growing data sets and a new space mission, 2007 is the first year in which we might discover another planet like our own. When marvelling at the stars on a clear night, it's hard to imagine that there are up to 400 billion of them in our Galaxy alone. Even harder to comprehend is how many planets may be orbiting these stars — a number that could run into trillions. Surely somewhere among them there must be a comfortable home for alien life, even if it's not advanced enough to be gazing back at us?
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