An Etymological Dictionary of Astronomy and Astrophysics

The seventh and largest of → Jupiter’s known satellites. This → Galilean satellite has a diameter of
5270 km, slightly larger than Mercury, a mass about 1.48 × 10²³ kg
(about 2 Earth Moons); an → orbital period of 7.155 days, and an → eccentricity of e = 0.0015. It was discovered by Galileo and Marius in 1610. The mean → surface temperature of Ganymede is -160 °C. It is the only moon known to have a → magnetosphere.

See also: In Gk. mythology, Ganymedes, a unusually beautiful prince of Troy who was abducted to Olympus by Zeus and made the cup-bearer of the gods.