Saturn's Moon Hyperion Poster

Saturn's impact-pummelled moon Hyperion stares back at the Cassini spacecraft in this six-image mosaic, taken during the spacecraft's close approach on Sept. 26, 2005. This up-close view shows a low-density body blasted by impacts over eons. Scientists believe that the spongy appearance of Hyperion is caused by a phenomenon called thermal erosion, in which dark materials accumulating on crater floors are warmed by sunlight and melt deeper into the surface, allowing surrounding ice to vaporise away. At 280 kilometres, (174 miles) across, Hyperion's impact-shaped morphology makes it the largest known irregularly-shaped moon in the solar system. Six, clear-filter images were combined to create this mosaic. Images were taken by the Cassini spacecraft narrow-angle camera at a mean distance of about 33,000 kilometres (20,500 miles) from Hyperion and at a Sun-Hyperion-spacecraft, or phase, angle of 51 degrees. Image scale is 197 metres (646 feet) per pixel.