NASA's Mars Global Surveyor shows a crater on the floor of the caldera, a large volcanic/collapse crater, of a giant martian volcano, Arsia Mons on Mars.

MGS MOC Release No. MOC2-394, 17 June 2003

In planetary science, impact craters are "tools of the trade." They are common to all of the solid-surfaced objects in our Solar System, and are thus a good point of reference to compare different planetary bodies. This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a crater that is about the same size as the famous Meteor Crater in northern Arizona, on the North American continent. This crater, however, is on the floor of the caldera--a large volcanic/collapse crater--of a giant martian volcano, Arsia Mons. This crater formed in volcanic rock, whereas the one in Arizona formed in sedimentary rock. Large, house-sized boulders dot the raised crater rim. This image is near 10.0°S, 120.4°W. The picture is illuminated from the left.

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