Tuesday | October 17, 2017
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Hawaii telescopes capture volcanic eruptions on Io

Two Hawaii Island telescopes captured images of several eruptions that are changing scientists’ understanding of volcanic activity on Io, one of Jupiter’s moons.

Ashley Davies, a volcanologist with NASA’s Jet Propulsion Laboratory at the California Institute of Technology in Pasadena, Calif., just returned from a trip on Hawaii Island testing a new camera on Pu‘u Oo, where he was studying lava flows. Davies collaborated with Imke de Pater, professor and chairwoman of astronomy at the University of California, Berkeley, and lead author of one of two papers describing the eruptions, in interpreting the data collected with the W.M. Keck Observatory and the Gemini Observatory.

Davies said he is beginning to be able to draw conclusions about Earth’s ancient lava eruption history, based on some of the eruptions being observed on Io. The Earth has “vast plains of lava,” but what scientists can see today is only the end result, Davies said. “Nobody really knows how these things were erupted in the first place. Io is starting to shine a very bright light on how the eruptions behaved.”

Scientists first observed the eruptions in the 1970s, Davies said. At first, scientists didn’t know exactly what they were seeing, and referred to the incidents as outbursts, because of the brief increase in light they emitted. The outbursts are generally thought to be fairly rare, observed about once a year, Davies said.

That is, until last year, when de Pater, using a Keck telescope, noted two eruptions in quick succession, on different parts of Io, on the same day. Within two weeks, de Pater and another UC Berkeley scientist, Katherine de Kleer, observed a third, even brighter eruption, using the Gemini North telescope.

“The frequency is one question that this (raised),” Davies said. “We’ve been speculating about what that might mean.”

Davies has been studying Io since his graduate student days. He said scientists are able to take what they see happen at an active volcano on Earth, including Kileaua and Mauna Loa, and apply that information to Io’s eruptions.

“You can understand how lava would behave on an alien environment,” he said.

At the same time, he said he can take what he observes on Io and apply it to current eruptions here, too. But just because Io is experiencing some of the same kinds of eruptions that were present on Earth, Mars and Venus when the planets were forming, Io isn’t likely to begin to take on characteristics similar to those planets through its volcanic activity, Davies said. For one, Earth, Mars and Venus have atmospheres, which affect how the planets formed, he said. Io does not.

Secondly, Io has a sulfur-rich surface, unlike those planets.

“What we’re seeing is pure volcanism,” Davies said. “It’s a huge amount of fun to watch.”

Davies said he was able to take the observations and calculate how much lava is being erupted. He said the eruptions may come in the form of “curtains of lava” up to 20 kilometers long. The volume of material ejected is incredibly high, and it comes out incredibly quickly.


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