Magnetic Field Found Around Jupiter Moon

Io, a moon of Jupiter that has surprised researchers before, may be a magnetized solid body, just like Earth and the planet Mercury, a study suggests.

A one-minute magnetic measurement of space around Io by the spacecraft Galileo last December detected a dramatic change that suggests the Jovian moon is generating its own magnetic field, researchers report in the journal Science.

“Io is much more dynamic than we expected it to be,” said Carol Polanskey of the Jet Propulsion Laboratory, one of the co-authors of the study. “This certainly suggests that Io has a magnetic field of its own” and could be a solid magnetized body as are Earth and Mercury.

Polanskey said this is consistent with the discovery in 1979 by the spacecraft Voyager that Io had volcanoes.

“It is not a dead rock,” she said.