MUST CREDIT: NASA/ESA/Rex Mandatory Credit: Photo by NASA/ESA/REX (4524328b) NASA Hubble Space Telescope images of Ganymede's auroral belts (coloured blue in this illustration) are overlaid on a Galileo orbiter image of the moon. The amount of rocking of the moon's magnetic field suggests that the moon has a subsurface saltwater ocean NASA's Hubble Observations Suggest Underground Ocean on Jupiter's Largest Moon - 12 Mar 2015 FULL COPY: http://www.rexfeatures.com/nanolink/q44p NASA?s Hubble Space Telescope has the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter?s largest moon. The subterranean ocean is thought to have more water than all the water on Earth's surface. Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search of life as we know it.