Ganymede (Jupiter III) is a seventh moon of Jupiter. With a diameter of 5,268 km. it is 8% larger than Mercury (but has only 45% of its mass) and 2% larger than Titan. Ganymede is probably composed of approximately equal amounts of silicate rock and water ice. A saltwater ocean is believed to exist nearly 200 km beneath its surface, sandwiched between layers of ice.
The possibility that it might be habitable has drawn recent attention from scientists.
- Robert A. Heinlein. 1953. Farmer in the Sky.
- The Oracle of Ganymede by Frank Cavallo. Raygun Revival. Volume 2, Issue 15. April 19, 2012.