Callisto: The heavily-cratered surface 9.18
Galileo view of a large part Callisto showing its dark, heavily-cratered surface. The younger impact craters are the most prominent, because their ejecta blankets have not yet become radiation-darkened.
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Image Credit: NASA  

Galileo view of a large part Callisto showing its dark, heavily-cratered surface. The younger impact craters are the most prominent, because their ejecta blankets have not yet become radiation-darkened. Towards the left is a multiringed impact basin named Valhalla. The 600 km diameter pale zone in Valhalla's centre marks the site of the original crater, but this was too large a structure for the lithosphere to support and its has long since collapsed. This is surrounded by rings of concentric fractures, the outermost having a diameter of 4000 km.  
Text credit: David A. Rothery Return to top of page