How many moons does Mars have? Mars has two moons. Phobos is the largest with diameter of 22.2 kilometers and Deimos is the smallest with diameter of 12.6 kilometers. These are irregular planetoids that Mars grabbed with his gravity. Both are covered with many craters and their density is much smaller than Mars density. They orbit at low altitudes and they nedd short time for a tour around Mars, Phobos need 7 hours and 39 minutes and Deimos need 30.30 hours.
The two moons of Mars, Phobos and Deimos, are somewhat different. While both have nearly circular orbits and travel close to the plane of the planet’s equator, they are lumpy and dark. Phobos is slowly drawing closer to Mars, and could crash into Mars in 40 or 50 million years, or the planet’s gravity might break Phobos apart, creating a thin ring around Mars.
Phobos and Deimos are, in Greek mythology, the sons of Ares (Mars) and Aphrodite (Venus). Phobos in Greek means "fear", and Deimos, "terror". Their low density suggests that they are not made of solid stone, but most likely from a mixture of rock and ice. It is assumed that these two satellites is actually captured asteroids formed in the outer part of the Solar System. They were discovered by the American astronomer Asaph Hall in 1877. and are named Phobos (Fear) and Deimos (Terror).
It seems that Deimos has the opposite fate of Phobos and at some point Deimos will finally rid of gravitational influence of Mars and leave it.