Phobos (moon) Phobos (moon) Phobos ( , , ; systematic designation: ) is the innermost and larger of the two natural satellites 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 and is seven times as massive as the outer moon, Deimos. Phobos is named after the Greek god Phobos, a son of Ares (Mars) and Aphrodite (Venus) and the personification of horror (cf. phobia). Phobos orbits from the Martian surface, closer to its primary body than any other known planetary moon.
Phobos (moon) who studied Phobos and people and places from Jonathan Swift's "Gulliver's Travels". A number of craters have been named, and are listed in the following table. There is one named regio, "Laputa Regio", and one named planitia, "Lagado Planitia"; both are named after places in "Gulliver's Travels" (the fictional Laputa, a flying island, and Lagado, imaginary capital of the fictional nation Balnibarbi). The only named ridge on Phobos is "Kepler Dorsum", named after the astronomer Johannes Kepler. The orbital motion of Phobos has been intensively studied, making it "the best studied natural satellite in the Solar System" in terms of