Deimos

Mars II

   Deimos ("DEE mos") is the smaller and outermost of Mars' two moons. It is the smallest known moon 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 10 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.

Open Issues

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