... Credit: Cassini Imaging Team , SSI , JPL , ESA , NASA Explanation: What has happened to Saturn's moon Iapetus? Vast sections of this strange world are dark as coal , while others are as bright as ice. The composition of the dark material is unknown, but infrared spectra indicate that it possibly contains some dark form of carbon . ... To help better understand this seemingly painted moon, NASA directed the robotic Cassini spacecraft orbiting Saturn to swoop within 2,000 kilometers in 2007. ...