Ganymede is the largest moon of Jupiter and the largest moon in Sol. It has a bigger diameter than Mercury, but half its mass. It was first discovered by Galileo Galilei in 1610.
Beneath the frozen surface of Ganymede is a saltwater ocean which could be habitable to life. It contains more water than all oceans on Earth.
- ↑ https://en.wikipedia.org/wiki/Ganymede_(moon)
- ↑ http://www.nasa.gov/press/2015/march/nasa-s-hubble-observations-suggest-underground-ocean-on-jupiters-largest-moon/#.VQJhMM26t0s