Adjective(s) Unknown
Orbital properties
Aphelion/apoapsis 23470.9 km
Perihelion/periapsis 23455.5 km
Semi-major axis 23463.2 km (6.92 Mars radii)
Orbital eccentricity 0.00033
Orbital period 1.263 d
(30.312 h)
Average orbital speed 1.3513 km/s[
Physical properties
Radius 6.2 ± 0.18
(0.97316 mEarths)
Mass 1.4762×1015
(0.247179 nEarths)
Mean density 1.471±0.166 g/cm3
Escape velocity Unknown
Rotation period Synchronous
Average surface temperature ≈ 233 K
Apparent magnitude 12.45 ± 0.05
Moons 0
Deimos is a moon of the planet Mars that orbits farther out than Mars's larger moon, Phobos.


It is predicted that Deimos, like Phobos, is an asteroid captured from the Asteroid Belt. This is plausible due to its size and shape.

Named Geoligical FeaturesEdit

Only two geological features on Deimos have been given names. The craters Swift and Voltaire are named after writers who speculated on the existence of two Martian moons before Phobos and Deimos were discovered.

Deimos Craters

Swift and Voltaire


  • Asaph Hall discovered it on August 12, 1877.
  • It orbits Mars every 30.35 days.
Martian Moons
Phobos - Deimos