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The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.
This picture shows Ligeia Mare, one of the ethane and/or methane "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
Image courtesy of NASA/JPL/USGS.

The Poles of Titan

Titan is the largest moon of Saturn. It is the second largest moon in the whole Solar System. Titan is the only moon with a thick atmosphere. Titan's poles are interesting places. Scientists have discovered lakes at both of Titan's poles. They also found small seas near the North Pole. They have also spotted clouds near each of the poles.

Titan is very cold. The surface 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. They are the first stable bodies of surface liquid found beyond Earth.

There are hundreds of lakes near Titan's North Pole. There are some that are so big that scientists are calling them seas. One sea (named Ligeia Mare) is about the size of North America's Lake Superior. There also lakes near the South Pole, though not as many.

So where did the liquid ethane and/or methane 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.

Last modified January 20, 2009 by Randy Russell.

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