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Dark Pit on Mars' Arsia Mons, with Sunlit Wall
dark pit seen on Mars

The High Resolution Imaging Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter has confirmed that a dark pit seen on Mars in an earlier HiRISE image really is a vertical shaft that cuts through lava flow on the flank of the Arsia Mons volcano. Such pits form on similar volcanoes in Hawaii and are called "pit craters."

This view, a small portion of a HiRISE image taken on Aug. 9, 2007, shows a dark pit about 150 meters (492 feet) in diameter set in a lava flow. The image was taken with the camera pointing slightly westward, instead of straight down. It catches the eastern wall of the pit lit by afternoon sunlight. The image was taken at 2:34 p.m. local Mars time.

The full HiRISE image that includes this view is online at

Credit: NASA/JPL-Caltech/University of Arizona

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