Seas on Titan

This image, taken by Cassini's radar instrument, shows bodies of liquid near Titan's north pole. The images show that many of the features commonly associated with lakes on Earth, such as islands, bays, inlets and channels, are also present on this cold Saturnian moon. They offer strong evidence that larger bodies seen in infrared images are, in fact, seas. These seas are most likely liquid methane and ethane.

For more than two decades, scientists have debated whether liquids on Titan exist, and if so, where they would be located. Pre-Cassini observations from the 1980s indicated that something on Titan's surface must be re-supplying the methane to its atmosphere. A global ocean was once hypothesized. Subsequently, disconnected lakes or seas were predicted. The discovery of numerous lakes near Titan's north pole by the Cassini radar instrument in July 2006 has confirmed the latter idea, and indicates an apparent preference during the current season for liquids to be located near the north pole.

These new observations of the north polar area show how extensive and widespread these lakes are, and reveal at least one body of liquid that might rightly be called a sea. These seas cover an area about 100 000 sq km, larger than Lake Superior, near the U.S. and Canadian border, whose area is 82 000 sq km. Analysis of the data indicates that the bodies of liquid may be tens of metres in depth.

The resolution of the radar data varies from several kilometres to as fine as 300 m.