Outermost large moon of Saturn, only spherical one in an eccentric, inclined orbit. Has two different "faces", one very bright and the other very dark. Has mountain range across its equator which significantly distorts its spherical shape.
Cassini Regio - The dark hemisphere of Iapetus, first detected by Giovanni Cassini, who noticed Iapetus was brighter when on one side of Saturn. Possibly formed due to different rates of sublimation of ices or as dark material landed their from Phoebe.
Roncevaux Terra - The primary bright area on Iapetus. Contains a very large crater Engelier.
Engelier Crater - Large crater on the bright hemisphere of Iapetus in Roncevaux Terra.
Iapetus Equatorial Ridge - Large equatorial ridge of Iapetus. Reaches 20 km high and is the highest formation in proportion to its size on any solar system world.