How Volcanoes Work

 Image Described in Caption
 Lunar Highlands and Maria -- The lunar highlands are the heavily cratered light regions of the moon, whereas the dark regions are the smooth-surfaced lunar maria. The large crater in the center of the left image is the Orientale Basin, which contains a small mare in its center. The image to the right is rotated about 75 degrees, so that the Oreintale basin is near the western side. The images were taken by the Galileo spacecraft. Courtesy of NASA.