Geography of Mars Aurorae Sinus. The largest dark feature seen from Earth is Syrtis Major Planum. The shield volcano, Olympus Mons ("Mount Olympus"), rises 22 km above the surrounding volcanic plains, and is the highest known mountain on any planet in the solar system. It is in a vast upland region called Tharsis, which contains several large volcanos. See list of mountains on Mars. The Tharsis region of Mars also has the solar system's largest canyon system, Valles Marineris or the "Mariner Valley", which is 4,000 km long and 7 km deep. Mars is also scarred by countless impact craters. The largest of
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