... Saturns Iapetus: Moon with a Strange Surface . ... Credit Copyright: Cassini Imaging Team , SSI , JPL , ESA , NASA Explanation: What has happened to Saturn's moon Iapetus? A strange ridge crosses the moon near the equator, visible near the bottom of the above image, making Iapetus appear similar to the pit of a peach . Half of Iapetus is so dark that it can nearly disappear when viewed from Earth. ... Publications with keywords: Saturn - Iapetus . ... A Close Pass of Saturns Moon Dione . ...