Photograph of the north west part of the Moon taken from Orange, California. The dark plain filling most of the frame is an enormous, lava- filled impact crater known as the Mare Imbrium. Ajoining this (top) is Sinus Iridum (the bay of rainbows), walled, to the north west, by the semicircular Jura Mountains. The bright, rayed crater at the bottom of the image is Copernicus. It is separated from the Mare Imbrium by the Carpathan Mountains, a remnant of the southern wall of the Imbrium crater. The small crater above and to the right of Copernicus is Eratosthenes.