Martian Moon Phobos is Discovered. One of the two natural satellites of Mars, Phobos, was discovered by American astronomer Asaph Hall. Hall also discovered Deimos, the other Martian Moon. Named after the Greek God of fear, Phobos orbits only 3700 miles from the surface of Mars, making it the Moon to orbit closest to its planet in the Solar System. Because of this, Phobos completes an orbit around Mars in 7 hours and 39 minutes.
Phobos (moon)