Summary: More than 70 percent of Earth’s surface is covered by water — more than 300 million cubic miles of it. Yet that’s just a drop in the ocean compared to the water on one of the moons of Jupiter. It may have two or even three times as much water as Earth — most of it contained in a salty ocean that’s hidden beneath the moon’s crust. Europa is slightly smaller than our own Moon. Unlike our dry, dusty Moon, though, Europa has water to spare. Its surface is a fairly thin crust of ice sitting atop what appears to be an ocean that enwraps the entire moon. This ocean could be 50 miles deep. Volcanic vents at its bottom may pump out hot water and a rich mixture of minerals — all of the raw ingredients for life. A recent study by geologists at the University of Texas found that there may also be liquid water inside the crust — pools of it as big as the Great Lakes. These pools may sometimes squirt water onto the surface, while getting more water from the ocean below — an ocean that dwarfs those here on Earth. Jupiter is just to the lower left of the Moon as they rise around midnight tonight, and looks like a brilliant star. The true star Aldebaran is a little farther to the right of the Moon. Through binoculars, Europa and three of Jupiter’s other big moons look like tiny stars quite near the giant planet. We’ll talk about another body that may have liquid water below its surface — the asteroid Ceres — tomorrow. Script by Damond Benningfield, Copyright 2012 For more skywatching tips, astronomy news, and much more, read StarDate magazine.
