MUST CREDIT: NASA/ESA/Rex Mandatory Credit: Photo by NASA/ESA/REX (4524328a) In this artist?s concept, the moon Ganymede orbits the giant planet Jupiter. NASA?s Hubble Space Telescope observed aurorae on the moon generated by Ganymede?s magnetic fields. A saline ocean under the moon?s icy crust best explains shifting in the auroral belts measured by Hubble 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.