Artistic Impression of Ganymede (Largest Moon in the Solar System)
NASA has confirmed that Ganymede, one of the moons orbiting Jupiter, has a saltwater ocean lying below its icy exterior, making it a viable location for life to flourish.
The scientists studying the planet and its outlier moons through the Hubble Telescope shared the news in a statement Thursday, saying that the ocean may bear more liquid than all the water on Earth combined.
Ganymede is an anomaly among moons. It is the largest known moon in our solar system, and the only one that generates its own magnetic field. This attribute produces a phenomenon called aurorae—strips of radiant electrified gas that circle Ganymede’s poles. Because Ganymede is situated so close to its mother planet, any changes to Jupiter’s magnetic field directly affect that of its moon. So when Jupiter’s magnetic field shifts due to the planet’s rotation, Ganymede’s aurorae “rock” back and forth in a sort of cosmic mating dance.
Observing the interplay between the planet and its moon, scientists surmised that an ocean works against Jupiter’s magnetic pull, causing Ganymede to rock less violently than they had anticipated. Once they had observed the planet with the Hubble Telescope, the researchers built computer models that supported speculation that Ganymede has a salty ocean.
Researchers believe the subterranean ocean is 10 times as deep as Earth’s oceans.
Since water is necessary to sustain life, it’s possible that these oceans may confirm the long-suspected presence of life on other planets, or on moons such as Titan and Enceladus.
NASA has speculated since the 1970s that there was water on Ganymede. A 2002 Galileo mission confirmed that the moon had its own magnetic field, but the findings weren’t concrete enough to corroborate suspicion that Ganymede had a vast ocean beneath its outer crust—until now. In a statement, an assistant administrator of NASA’s Science Mission Directorate, John Grunseld, said, “A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.”