Jupiter's moon Io's volcano clusters are offset hundreds of… (NASA/JPL )
Like the offset eyes on a Picasso portrait, the volcanoes on Jupiter’s moon Io seem to be strangely shifted, according to a study by NASA and ESA scientists.
Io’s clustered volcanoes seem to be lying 30 to 60 degrees eastward of where they were expected, according to a paper published this year in Earth and Planetary Science Letters. The study could shed light on the internal dynamics of Jupiter’s volcano-pocked moon.
Io’s internal heat comes from the kneading it gets from Jupiter and its fellow moons. Jupiter’s massive gravity pulls on the planet, stretching it one way. Meanwhile, tugs from fellow moons Europa and Ganymede stretch it from another direction. As Io flexes, internal friction from all that distortion heats up the interior, leading to its iconic volcanoes.
“It’s really a place that’s very much alive and very much changing,” said study lead Christopher Hamilton, an Earth and planetary scientist at NASA's Goddard Space Flight Center in Greenbelt, Md.
The patterns of the volcanoes can provide a road map to a planet’s (or a moon’s) internal structure, said Hamilton, who has looked at similar patterns on Earth and Mars. In theory, hot spots on the outside should tell scientists about what's happening on the inside.
Hamilton decided to tackle a longstanding question -- given what researchers know about Io, did the volcano layout match the predicted patterns?
Scientists have been mapping Io surface using data from the Voyager and Galileo spacecraft. Searching for patterns in this map, Hamilton found that clusters of volcanoes were shifted some 30 to 60 degrees eastward -- which, at the equator, translates to a roughly 600-to-1,200 mile offset. (Farther away from the equator, that translates to a smaller offset.)
Hamilton called the results surprising, pointing out a few possible explanations. Among them: It could be that the moon is rotating faster than expected, thus leading to the shift on the surface. It could be that Io is harboring a magma ocean within. That would be an exciting discovery, he added: Magma oceans were thought to be a mark of the early planets and moon as they formed and cooled.
“It’s like finding a still-living example of something that’s a fossil everywhere else,” Hamilton said.