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Galileo Finds Mysterious Magnetic Field at Ganymede

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Science  19 Jul 1996:
Vol. 273, Issue 5273, pp. 311
DOI: 10.1126/science.273.5273.311


Jupiter's largest moon, Ganymede, bears the scars of ancient volcanoes and lava flows, but the moon's era of turbulence was thought to be long over. Now new results from the Galileo spacecraft, which swung close by Ganymede on 27 June, show that the moon's calm, icy surface hides a hot and dynamic interior. Galileo found clear signs of a magnetic field, implying that the moon has a churning, molten core of metal.