Astronomers have found the most conclusive evidence yet that a large watery ocean lies beneath the surface of Jupiter’s moon Ganymede…With the discovery, Ganymede joins Enceladus and Europa as another moon in the solar system with a confirmed subterranean ocean.
“The solar system is now looking like a pretty soggy place,” said Jim Green, director of planetary science at NASA. “The more we look at individual moons, the more we see that water is really in enormous abundance.”
And where there’s water, there’s a chance of life.
Scientists have suspected for decades that a subterranean ocean might slosh between the rocky mantle and icy crust of Ganymede, the largest moon in our solar system, but they had not been able to prove it definitively until now.
Using the Hubble Telescope, a team of researchers has detected slight fluctuations in two bands of glowing aurorae in Ganymede’s atmosphere that they say could occur only if the moon contained a salty body of water…
Saur figured that…regular shifts in Jupiter’s magnetic field would affect the position of the aurorae in Ganymede’s atmosphere differently depending on whether or not the moon has a subsurface ocean.
Computer models show that if Ganymede did not have a subsurface ocean, the changes in Jupiter’s magnetic field should cause the bands of hot, electrically charged gas to rock six degrees over a 10-hour period. However, if the moon contained a salty ocean, it would reduce the rocking of the auroras to just two degrees.
The reason for the difference is that a saltwater ocean is electrically conductive and creates a secondary magnetic field that would suppress the effects of Jupiter’s magnetic field.
Saur looked at measurements taken by the Hubble Telescope in 2010 and 2011 of auroras over both the north and south poles of Ganymede and saw that the auroras only moved two degrees over a seven-hour period…
As astronomers continue their search for life elsewhere, this technique could help them to identify what other bodies might harbor water and, perhaps, life forms beyond Earth.
Interesting stuff. Yes, I’d love to be in on the trip to Ganymede for a walkabout. See if we can find some subsurface beachfront property.