Jupiter's moon Ganymede is the largest moon in the solar system; at over 3,200 miles across, it is larger than the planet Mercury. It is also the only moon with its own intrinsic magnetic field, produced by a churning central core of electrically conductive metal called a dynamo. But how Ganymede's unique dynamo works is still a mystery.

Models to explain Ganymede's formation and dynamo have been developed, but they are at odds with each other. Now, a study led by Caltech proposes a new mechanism to reconcile the two—one that suggests Ganymede's interior may still be warming up.

A paper describing the research appears in the journal Science Advances on May 6.

"Dynamos are one of the few ways we can understand what's happening deep in a body's interior with spacecraft data," says lead author Kevin Trinh, the Melza M. and Frank Theodore Barr Foundation Postdoctoral Scholar Research Associate in Planetary Science.…