Jupiter's Moon, Ganymede May Have a Massive, Underground Ocean That Impacts Aurorae

NASA's Hubble Space Telescope may have discovered water in a somewhat unusual location beyond our planet. After watching aurorae glowing above Jupiter's moon, Ganymede, scientists believe that the world may possess an underground ocean.

"This discovery marks a significant milestone, highlighting what only Hubble can accomplish," said John Grunsfeld, assistant administrator of NASA's Science Mission Directorate, in a news release. "In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth."

Ganymede is the largest moon in our solar system. It's also the only moon in our solar system with its own magnetic field. This field actually causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is so close to Jupiter, it's also embedded in Jupiter's magnetic field. This means that when Jupiter's magnetic field changes, the aurorae on Ganymede also change.

In this latest study, the scientists used the telescope to watch the rocking motion of the two aurorae. Because the aurorae are tied to the core of the moon, the researchers were able to tell a bit more about the makeup of Ganymede by watching the aurorae. After watching the phenomena, the scientists realized that the aurorae's behavior could be explained by a massive, underground saltwater sea.

If a saltwater ocean were present, Jupiter's magnetic field would create a secondary magnetic field int eh ocean that would counter Jupiter's field. This "magnetic friction" would suppress the rocking of the aurorae. In fact, this ocean fights Jupiter's magnetic field so strongly that it reduces the rocking of the aurorae to two degrees instead of the six degrees if the ocean were not present.

The researchers believe that the ocean on Ganymede is about 60 miles thick, which is 10 times deeper than Earth's oceans. This ocean is buried under nearly 95 miles of crust that's made up of mostly ice.

The findings reveal a bit more about the icy moon. Not only that, but it could mean that there may be the possibility for life on the moon within the depths of these deep waters.

The findings are published in the Journal of Geophysical Research: Space Physics.

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