Move over, Europa. Make way, Callisto. You're not the only moons of Jupiter that might hold seas of liquid water. Big brother Ganymede may also harbor an ocean beneath its icy surface, three new studies suggest. And where there's water, there could be life.
A layer of saltwater, at least several kilometers deep and buried some 150 kilometers beneath Ganymede's surface, is the best explanation for magnetic measurements that the Galileo spacecraft recorded, says
Margaret G. Kivelson of the University of California, Los Angeles.
Magnetic readings of Ganymede, taken during flybys over several years, reveal that Jupiter's largest moon has both a fixed magnetic field of its own and a secondary field induced by Jupiter. It's the induced field that suggests an unseen, salty ocean,