* Astronomy

This radar image shows the entire scene in which hydrocarbon lakes were first discovered on Titan, near its north pole (see Lakes on Titan). This image was acquired on July 22, 2006, by Cassini's radar instrument in synthetic aperture mode.


Expand (5.1mb, 18991 x 1920)
Credit NASA

The most striking landforms are the lakes: dark patches, some circular, some irregular, many with apparently steep rims, over much of the terrain north of 70 degrees latitude. The most convincing lake forms occur at the narrowest, central part of the scene, which is at the highest latitudes. Here they have short, stubby channels leading into them, and brighter areas within that indicate either dried-up lakes or that we are seeing through a transparent liquid.
The image also shows the considerable variation in the kinds of surface features found at different latitudes. Beginning at the left (20 degrees north by 142 degrees west) and heading north, a circular feature about 75 kilometres in diameter is seen, which could be either an impact crater or a volcanic caldera. Other less distinct circular forms are seen next, possibly including some dried lakes, followed by some ridge-like terrain with dark meandering channels or valleys. The dark lakes begin to appear next (at about 70 degrees north), with more distinct lakes in the middle of the scene, where the swath is closest to the pole and starts to descend to the south. Farther on, apparently dry lakes and canyons begin to dominate, and the region becomes more complex and etched. At the extreme right end, dunes similar to those seen previously mingle with brighter features. The swath ends at 13 degrees north by 347 degrees west.