This picture shows one of the "seas" on Titan. This picture was made with radar data from the Cassini spacecraft. The colors in the picture have been added. Blue areas are liquid ethane/methane, while brown areas are "dry land". This sea is near Titan's North Pole. It is slightly larger (in area) than Lake Superior on Earth. Click on image for full size (255 Kb) Image courtesy of NASA/JPL/USGS.

Titan is Saturn's biggest moon. Titan is the only moon in the Solar System with a thick atmosphere. Titan's poles are interesting places. Scientists have discovered lakes at both of Titan's poles. The scientists have also spotted clouds near each of the poles.

Titan is very, very cold. The temperature is around -179° C (-290° F). At that temperature water ice is as hard as rock. There is lots of methane and ethane on Titan. On Earth, methane is a gas. Many people use methane, also called natural gas, as a fuel in their home furnaces. On Titan, the cold temperatures turn methane and ethane into liquids. Titan's lakes and seas are filled with liquid ethane and methane instead of water.

There are hundreds of lakes near Titan's North Pole. There are some that are so big that scientists are calling them seas. There also lakes near the South Pole, though not as many.

Where did the liquid in the lakes and seas come from? Astronomers have spotted clouds over both of Titan's poles. One cloud over the North Pole was really, really big - about half as large as the United States. Maybe methane or ethane rain or snow falls from those clouds to Titan's surface, filling the lakes.