Io is Jupiter's innermost Galilean moon that is 2,300 miles wide, approximately the same size as our moon, and is the only place in the solar system (except Earth) where active volcanoes have been observed. The volcanic activity is driven by powerful tidal interactions with the gas giant that squeeze Io's interior, heating it up. Like Earth's volcanoes, molten rock (magma) is then forced through Io's crust intermittently erupting as volcanoes.
Many Io eruptions are surprisingly powerful and, because of the moon's low gravity, can blast debris high into space, forming a huge umbrella.
NEWS: Jupiter's Moon Conceals Ocean of Magma
"These new events are in a relatively rare class of eruptions on Io because of their size and astonishingly high thermal emission," said co-investigator and volcanologist Ashley Davies, from NASA's Jet Propulsion Laboratory and Caltech, in Pasadena, Calif. "The amount of energy being emitted by these eruptions implies lava fountains gushing out of fissures at a very large volume per second, forming lava flows that quickly spread over the surface of Io."