Given the enormity of the Universe, it seems certain: There must be other Sunlike
stars surrounded by Earthlike planets, teeming with microbes and ecosystems, and yes, even
species like us. Despite the logic of this premise, scientists have been unable to find the planets --
until now. In the past couple of years, astronomers searching for extrasolar planets have built
strong evidence for numerous distant worlds. These discoveries, combined with tantalizing
evidence for life on Mars and, more recently, the Jovian moon, Europa, lend powerful new
credence to the notion that we are not alone.