The Moons of Mars Mars has two small moons that are illustrated in the following figures, Phobos and Deimos. Phobos (Ref) Deimos (Ref) These are examples of what are called minor satellites: small chunks of rock in orbit around planets as compared with large satellites like the Earth's Moon. As the adjacent images show, they are very irregular in shape. Phobos is 27 km long in its longest ...

Mars' Moons - Phobos & Deimos, from ORRERY: the Solar System in action.

Phobos and Deimos Mars is orbited by two satellites, both believed to be captured asteroids. This is because of both Mars' proximity to the Asteroid Belt and their small sizes and irregular shapes. The table below provides some information on their dimensions and orbital characteristics (Illingworth, 1994). Satellite Year of Discovery Diameter (Km) Orbital Radius (Km) Eccentricity Orbital Period ...