Ss:Phoebe

Outermost relatively large moon of Saturn. A dark large irregular moon. First moon targeted by Cassini. Source of dark hemisphere of Iapetus. Smaller fragments land on Hyperion and Titan.

Source of Dark Material on Iapetus and Other Moons (Jul 2011)

 * http://www.sciencenews.org/view/generic/id/332324/title/Iapetus_gets_dusted