The Cassini spacecraft’s radar sweep of Saturn’s largest moon Titan in January revealed a portion of what appears to be a 110 mile (180 kilometer) diameter This would only be the fourth such crater discovered on Titan, a surprisingly small number. Impact cratering is pervasive in our solar system. Earth's Moon remains heavily pockmarked because it has no significant weather or geological processes to wipe its face clean. Earth, similarly bombarded over the eons, shows many scars from relatively recent impacts that have not had time to weather away. Craters are common on several other satellites of Saturn. If Titan's surface had the same density of craters that other Saturnian moons have, there should be thousands of craters. With only three and a half dozen possibles, the question is "where did all the craters go?" Titan’s thick nitrogen atmosphere is partly responsible. It hinders the formation of impact craters less than about 12 miles (20 kilometers) in diameter, because smaller space rocks burn up before they reach the surface. Clues to Titan’s smooth finish can be seen in the presence of vast tracts of sand dunes, river channels and evidence for cryovolcanism visible in Cassini images. It is likely that a combination of burial in sand, erosion by methane or obliteration by the cold hand of cryovolcanism is responsible for paving over the craters.
Submitted by Shaun A. Saunders
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