Micrometeorites constantly chip away at Saturn's C-ring. From Mars . Inside the vast Valles Marineris Canyon complex, Viking Orbiter photos have picked out wind-blown patches of dark material. These patches are strung out along faults for some 200 kilometers.
Astronomers believe they are volcanic vents, which are a scant few million years old.
Another of the surprisingly large number of youthful features in the solar system. From Europa . The surface of Europa, one of Jupiter's large Galilean satellites, seems to be covered with a relatively smooth veneer of ice. Beneath this frigid skin, according to one theory, lie about 100 kilometers of liquid water. William R. Corliss Other Sites of Interest SIS .