Moon and Jupiter

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• 719 of 1997
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Water, it turns out, is common throughout the solar system. We've got lots of it here on Earth, but it's also found on other planets and moons. Two examples huddle close together this evening: the Moon and the planet Jupiter. They're in the southwest as night falls, and set in mid-evening. Jupiter looks like a brilliant star to the Moon's upper left.

The water on these two worlds is in different forms, though. On Jupiter, it's both a liquid and a gas. But on the Moon, it's frozen solid.

Jupiter is basically a big ball of gas topped by a turbulent atmosphere. Water vapor in the atmosphere condenses to form clouds. These clouds spawn violent thunderstorms, with lightning blasts a thousand times more powerful than those on Earth. As rain falls from the clouds, it drops many miles deeper into the atmosphere, where it heats up and vaporizes. The water vapor then rises back to higher altitudes, where it cools and forms more clouds.

An orbiting spacecraft discovered evidence of frozen water on the Moon back in the 1990s -- inside craters that never see the light of day.

More recently, three other craft found even more water -- individual molecules mixed in with the powdery lunar soil. They found that the water is more widespread than expected. Even so, it's still not much. If you squeezed all the water molecules out of a ton of surface material, you'd get about a quart of water.

More about Jupiter and the Moon tomorrow.

Script by Damond Benningfield, Copyright 2009

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