Olympus Mons the height of Mauna Kea as measured from its base on the ocean floor). The total elevation change from the plains of Amazonis Planitia, over to the northwest, to the summit approaches . The summit of the mountain has six nested calderas (collapsed craters) forming an irregular depression × across and up to deep. The volcano's outer edge consists of an escarpment, or cliff, up to tall (although obscured by lava flows in places), a feature unique among the shield volcanoes of Mars. Olympus Mons covers an area of about , which is approximately the size of Italy, and it
Minor planet more are discovered each month. The Minor Planet Center has documented over 188 million observations and 757,626 minor planets, of which 516,386 have orbits known well enough to be assigned permanent official numbers. Of these, 21,264 have official names. , the lowest-numbered unnamed minor planet is , and the highest-numbered named minor planet is 495759 Jandesselberger. There are various broad minor-planet populations: All astronomical bodies in the Solar System need a distinct designation. The naming of minor planets runs through a three-step process. First, a provisional designation is given upon discovery—because the object still may turn out to be a