Meteors have a way of leaving their mark when a) they're big; and b) they become meteorites (a meteor is in the atmosphere; a meteorite has hit the ground).

This Mars Global Surveyor image, made in April, shows an old meteorite impact crater that was buried long ago, but then later partially unburied from within the layered rocks on the floor of a much larger (and older) crater in eastern Arabia Terra.

The erosion processes that began to exhume the crater, however, stopped some time ago, because today the whole area is covered by a blanket of dust, said astronomers with Malin Space Science Systems, which operates the spacecraft's camera.

Avalanches of this dust have created dark streaks on the walls of the partly exhumed crater. This photo covers an area of 1.9 miles (3 kilometers) near 20.9°N, 320.8°W. Sunlight illuminates the scene from the lower left.

-- Robert Roy Britt