Rainy Days
 A swoosh of clouds slashes across the northern hemisphere of Saturn's moon Titan in this 2008 image from the Cassini spacecraft. The clouds are at the top center of the picture. Researchers say that a steady drizzle of liquid hydrocarbons may soak much of Titan. Flowing liquids appear to carve rivers on Titan, filling large lakes. [NASA/JPL/SSI]
Titan is about half again as big as our own Moon. Unlike our Moon, though, it's blanketed by a thick, cold atmosphere. A "smog" of organic compounds tops the atmosphere, giving Titan a dirty yellow color.
Titan is hundreds of degrees colder than Earth, so water is frozen as hard as rock. But Titan does have liquids -- methane and ethane. They appear to pool in big lakes around Titan's poles, and carve rivers as they flow across the surface.
Methane also appears to form thin clouds high in Titan's atmosphere. Recent observations show that the clouds are pretty much constant across the entire moon.
The clouds may produce a steady drizzle -- especially along a mountain range at the edge of Xanadu, Titan's largest continent. Winds may push moisture up the slope of the mountains. At higher altitude, it condenses to form clouds and drizzle. The drizzle is seen in the early mornings -- which last several Earth days on Titan, where a day is more than two weeks long.
Saturn is high in the southeast at nightfall, and wheels westward during the night. It looks like a bright golden star, with the true star Regulus close by. Small telescopes reveal Titan -- a place where it's cold and damp all year long.
Script by Damond Benningfield, Copyright 2008
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