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One of the most active bodies in the solar system.

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Despite a number of close-flying spacecrafts over the past few decades — including the Voyager 1 and Galileo missions — as well as constant observation from Earth, there are lasting mysteries about the kind of volcanic activity on Io and how the moon’s fiery energy interacts with Jupiter and other nearby bodies.

Last year, Dr. Morgenthaler, who studies gases Io emits and the cloud said gases create around Jupiter, picked up signs that a different kind of eruption — a more powerful or more persistent one — was occurring.

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