The planet Jupiter follows the Moon across the sky in the wee hours of tomorrow morning. It's the brilliant star-like point of light to the lower left of the Moon at first light.
One of Jupiter's moons is a prime target for the next round of missions to the planets. That's because Europa appears to have an ocean of liquid water beneath its icy crust. Liquid water means there's a source of heat, and the combination means that Europa could be a comfortable home for life.
We can't see Europa's ocean, but several lines of evidence suggest it's there.
For one thing, Europa's surface is quite young -- almost no craters pockmark the ice. A young surface means that something is happening to change the surface -- in this case, the ice is remolded as it drifts atop the ocean, or fresh water spills to the surface and freezes.
For another, sections of ice form the same sorts of formations that we see in ice sheets here on Earth -- the ice is jumbled about as water currents move it around.
And for yet another, measurements of Europa's magnetic field suggest that something is sloshing around below the surface -- like an ocean of salty water.
NASA and the European Space Agency recently agreed that Europa is a key target for exploration. The agencies are planning for a mission to explore the icy world in more detail. Eventually, they may even send a submarine to dive into Europa's icy depths.
More about Jupiter and the Moon tomorrow.
Script by Damond Benningfield, Copyright 2009
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