Title: Olympus Mons, Mars

Source: U.S. Geological Survey, Flagstaff, Arizona

Information: Shown here is a digital mosaic of Olympus Mons, the largest known volcano in the solar system. It is 27 kilometers high, more than 600 kilometers at the base, and is surrounded by a well-defined scarp that is up to 6 kilometers high. Lava floes drape over the scarp in places. Much of the plains surrounding the volcano are covered by the ridged and grooved "aureole" of Olympus Mons. The origin of the aureole is controversial, but may be related to gravity sliding off the flanks of an ancestral volcano. The summit caldera (central depression) is almost 3 kilometers deep and 25 kilometers across. It was probably formed from recurrent collapses following drainage of magma resulting from flank eruptions. This image was produced by merging the Mars medium resolution Digital Image Model with low-resolution color observations at the U.S. Geological Survey in Flagstaff, Arizona.