Mars with its two moons
Mars' moon Phobos is seen against the darkness of space.
A color-enhanced image of Mars' moon Deimos. Deimos has a smooth surface except for the most recent impact craters. It is a dark, reddish object.

Moons of Mars

Mars has two moons, Phobos and Deimos. Both are thought to be captured asteroids, or debris from early in the formation of our solar system. Phobos is the larger of Mars' two moons. It orbits Mars three times a day, and is so close to the planet's surface that in some locations on Mars it cannot always be seen. Phobos is nearing Mars at a rate of six feet (1.8 meters) every hundred years. At that rate, it will either crash into Mars in 50 million years or break up into a ring. Deimos is the smaller moon. It orbits Mars every 30 hours.

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August 1877




Asaph Hall

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