You don't really expect to find anything living inside a giant ice cube -- unless the ice cube is a moon of one of the giant planets. In fact, two ice moons -- one of Jupiter and one of Saturn -- are considered among the best candidates for life in the solar system.
The Jovian moon is Europa. It's bigger than our own Moon, and a lot more interesting. There's abundant evidence that an ocean of liquid water lies below its icy crust -- the result of a tug-of-war between Jupiter and some of its other big moons.
Jupiter's gravity "locks in" Europa so that the same side of the moon always faces Jupiter. As Jupiter's other big moons pass by Europa, though, they try to turn it away from Jupiter. That heats the moon's interior, melting some of its ice. The heat could also power geothermal vents like those at the bottom of Earth's oceans. These vents would pump out warm water and chemicals -- providing a cozy environment for life.
The Saturnian moon is Enceladus. It's a lot smaller than Europa, but scientists don't have to wonder if it has liquid water -- they know it does. Water squirts into space from hot spots around the south pole.
We don't know what the prospects of finding life on these worlds really are. But we do know that Europa and Enceladus appear to have the right ingredients for life: water, an energy source, and the right chemistry. Now all we have to do is go and look for it.
We'll look for life on another moon tomorrow.
Script by Damond Benningfield, Copyright 2010
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