While the surfaces of most of the Solar System’s moons are dominated by impact craters, the surface of Titan, Saturn’s largest moon, features very few craters. Until recently only seven craters had been spotted on Titan (5,150 km across).
However, on 21 June 2011, a radar instrument aboard the Saturn-orbiting Cassini spacecraft discovered an eighth impact crater on Titan. This newly found crater is about 40 km across, and is surrounded by a cover of ejecta, material thrown out from the crater, that appears bright in radar images, and extends roughly 15-20 km beyond the crater’s rim.
Interestingly, dunes, visible as dark lines on image’s left, have been swept toward the crater by the winds of Titan, the only planetary moon with a thick atmosphere.
One reason for the scarcity of craters on Titan is that the moon's dense atmosphere destroys the smaller falling meteorites, before they can hit the surface. The craters that do form are often difficult to identify, or disappear entirely, as they are eroded over time by geological processes, including the wind-driven motion of sand and, possibly, ice volcanoes. Ice volcanoes, also known as cryovolcanoes, are a rare type of volcanoes that occurs on icy moons. They spew very cold material, instead of incandescent lavas and hot vapors. They have been discovered on another Saturnian moon, known as Enceladus, and on Triton, Neptune’s largest moon.
References
A New Crater for Titan
http://photojournal.jpl.nasa.gov/catalog/PIA14744
NASA
www.nasa.gov/
Wikipedia
Further Reading
The Cassini Mission Homepage
http://saturn.jpl.nasa.gov/index.cfm