Apr 10, 2008

The Stickney Crater of Phobos

This is an image of Phobos, a moon of the planet Mars. This image shows the largest crater on the martian moon - the Stickney Crater. This image was sent by the HiRISE camera onboard the Mars Reconnaissance Orbiter. Over 9 kilometers across, Stickney is nearly half the diameter of Phobos itself, so large that the impact that blasted out the crater likely came close to shattering the tiny moon.

The Stickney Crater is named after Chloe Angeline Stickney Hall, mathematician and wife of astronomer Asaph Hall. Asaph Hall discovered both the Red Planet's moons Phobos (mean diameter, 22.0 km) and Deimos (mean diameter, 14.0 km), in 1877.

Even though the surface gravity of asteroid-like Phobos is less than 1/1000th Earth's gravity, streaks suggest loose material has slid down inside the crater walls over time. Light bluish regions near the crater's rim could indicate a relatively freshly exposed surface. The origin of the curious grooves along the surface is mysterious but may be related to the crater-forming impact. NASA


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