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Deimos, Moon of Mars

Deimos ("DEE mos") is the smaller and outermost of Mars' two moons. It is one of the smallest known moons in the solar system.

         orbit:    23,459 km from Mars
         diameter: 12.6 km (15 x 12.2 x 11)
         mass:     1.8e15 kg

In Greek mythology, Deimos is one of the sons of Ares (Mars) and Aphrodite (Venus); "deimos" is Greek for "panic".

Discovered 1877 August 12 by Hall, photographed by Viking 1 in 1977.

Deimos and Phobos are composed of carbon-rich rock like C-type asteroids and ice. Both are heavily cratered.

Deimos and Phobos are probably asteroids perturbed by Jupiter into orbits that allowed them to be captured by Mars.

More about Deimos

Open Issues

  • There is no completely satisfactory theory as to how Deimos and Phobos came to be in orbit around Mars.