Phobos
Phobos (pronounced FOH bus) is the largest of the two moons which orbit the planet Mars. Phobos is innermost moon of Mars, the other being Deimos. Both moons were discovered in 1877 by American astronomer Asaph Hall. Phobos is a small, irregularly shaped object with a mean radius of 11 km and is seven times as massive as the outer moon, Deimos.
How Phobos got its name
Phobos was the god of fear in Greek mythology, and son of the gods Ares and Aphrodite. He was the brother of Deimos. He followed his father into battle, along with his companions, Enyo (the war goddess); Eris (the goddess of discord); and his brother, Deimos.
Comparison
Phobos is closer to it's parent planet than any other satellite in the solar system. Phobos travels only 3,700 miles (6,000 km) above the surface of the red planet – by comparison the Moon is 384,400 km above Earth. Phobos orbits Mars three times per day and because of it’s proximity to Mars, astronomers weren’t able to see the moon until the 19th century when it was discovered by American astronomer Asaph Hall on August 18, 1877, 6 days after he discovered the moon Deimos.