Moons of Mars Moons of Mars The two moons of Mars are Phobos and Deimos. Both were discovered by Asaph Hall in August 1877 and are named after the Greek mythological twin characters Phobos (panic/fear) and Deimos (terror/dread) who accompanied their father Ares, god of war, into battle. Ares was known as Mars to the Romans. Phobos orbits closer to Mars, with a semi-major axis of to Deimos' . The existence of the moons of Mars had been speculated about since the moons of Jupiter were discovered. It is known that when Galileo, as a hidden report about him having observed two bumps
Formation and evolution of the Solar System possibility is where the primary and moon are tidally locked to each other. In that case, the tidal bulge stays directly under the moon, there is no transfer of angular momentum, and the orbital period will not change. Pluto and Charon are an example of this type of configuration. Prior to the 2004 arrival of the "Cassini–Huygens" spacecraft, the rings of Saturn were widely thought to be much younger than the Solar System and were not expected to survive beyond another 300 million years. Gravitational interactions with Saturn's moons were expected to gradually sweep the rings' outer edge toward the