The surface of Io, the innermost moon of Jupiter, is not a very hospitable place. It's the most volcanically active body in our solar system, and last August, three massive eruptions took "fiery" to a whole new level.
Forces exerted on Io from its host planet and fellow moons Europa and Ganymede cause tremendous tides that make Io's surface bulge out by as much as 330 feet, according to NASA. The thing is, Io's surface is solid, not liquid, so those tidal forces ensure its subsurface crust stays a boiling hot liquid, which constantly looks for any escape route it can get. Which means there is a lot of volcanic activity on the moon.
But even for the hellish surface of the Jovian moon, last August represented a particularly violent month, according to two papers just accepted for publication by the journal Icarus. During that period, astronomers spotted three massive volcanic eruptions on Io, one of which was among the brightest ever seen on the moon. It is believed that the volcanoes all erupted from long fissures in Io's surface reaching up to several miles long, and that the lava spewed upward in what are being described as "curtains of fire."
"These new events are in a relatively rare class of eruptions on Io because of their size and astonishingly high thermal emission," said Ashley Davies, co-author of one of the papers, in a statement. Davies is a volcanologist with NASA's Jet Propulsion Laboratory in Pasadena, California. "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," he added.
From 1978 to 2006, only 13 large eruptions were spotted on Io, so finding three in one month is extremely rare. The brightest of the first two eruptions spotted last August produced a 50-square-mile, 30-foot-thick lava flow.
By studying volcanic activity on Io, astronomers hope to gain a better understanding about the formation of our solar system. In fact, Imke de Pater, professor and chair of astronomy at the University of California, Berkeley and lead author of one of the two papers describing the eruptions, said that the biggest of all three eruptions was "indicative of a composition of the magma that on Earth only occurred in our planet's formative years."
"We are using Io as a volcanic laboratory, where we can look back into the past of the terrestrial planets to get a better understanding of how these large eruptions took place, and how fast and how long they lasted," Davies added.