Iapetus A Mixture Of Light And Dark

Iapetus, one of Saturn's 31 known moons,  has a mixture of very dark and very light coloring on its surface as shown very clearly in recent Cassini images.  The contrast is not an illusion and is not due to shadowing, but is due to the composition of the surface materials.  Scientists do not yet know whether the dark material has been deposited from an external source - possibly one of Saturn's other moons, Phoebe - or whether it originates from inside the moon itself.  Cassini will continue to study Iapetus periodically throughout its mission.

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