Department of Climate and Space Sciences and Engineering in the College of Engineering at the University of Michigan


Dr. Jia’s research suggests an underground sea on Ganymede

Posted: March 12, 2015

Dr. Jia’s research suggests an underground sea on Ganymede

Assistant Research Scientist Dr. Xianzhe Jia co-authored a recent paper that shows evidence for an underground saltwater ocean on Ganymede, Jupiter’s largest moon.

Ganymede is the largest moon in the solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter’s magnetic field. When Jupiter’s magnetic field changes, the aurorae on Ganymede also change, “rocking” back and forth, according to a NASA press release.

By watching the rocking motion of the two aurorae, Jia and the research team were able to determine that a large amount of saltwater exists beneath Ganymede’s crust, affecting its magnetic field.

The paper is published online in the Journal of Geophysical Research: Space Physics. It is titled, “The search for a subsurface ocean in Ganymede with Hubble Space Telescope observations of its auroral ovals.”

The findings have been discussed on,, and in USA Today.

To read the paper, please visit

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