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Updated: Jul 14, 2026

Bringing the Visible Universe into Focus with Robo-AO
Published on: February 12, 2013
Discovery of mass anomalies on Ganymede
John D Anderson1, Gerald Schubert, Robert A Jacobson
1Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109-8099, USA. john.d.anderson@jpl.nasa.gov
Abstract:
We present the discovery of mass anomalies on Ganymede, Jupiter's third and largest Galilean satellite. This discovery is surprising for such a large icy satellite. We used the radio Doppler data generated with the Galileo spacecraft during its second encounter with Ganymede on 6 September 1996 to model the mass anomalies. Two surface mass anomalies, one a positive mass at high latitude and the other a negative mass at low latitude, can explain the data. There are no obvious geological features that can be identified with the anomalies.
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