Ganymede (Sol 5c) is a moon of Jupiter (Sol V), United Empire of Earth (UEE). The largest moon in the Sol system, its diameter is greater than that of the planet Mercury (Sol I). Before Ganymede's subsurface ocean was explored in the 25th century SEY, it was popularly speculated that the moon may have had extraterrestrial life. No forms of life in the past or present have thus far been observed.