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PHOBOS

DEIMOS
(fear) (panic)

PHOBOS AND DEIMOS

(moons of Mars)

Mars has two small moons: Phobos and Deimos. Phobos (fear) and Deimos (panic) were named after the horses that pulled the chariot of the Greek war god Ares, the counterpart to the Roman war god Mars. Both Phobos and Deimos were discovered in 1877 by American astronomer Asaph Hall. The moons appear to have surface materials similar to many asteroids in the outer asteroid belt, which leads most scientists to believe that Phobos and Deimos are captured asteroids.

Quick Facts about Phobos and Deimos

Phobos Deimos

Mean distance from Mars (km) 9377 23436
Orbital period (Mars days) 0.31891 1.26244
Major axis (km) 26 16
Minor axis (km) 18 10
Mass (x 1015 kg) 10.8 1.8
Mean density (kg/m3) 1900 1750