A two-week period of giant volcanic eruptions from Jupiter's moon Io, revealed in images released this week, included one of the brightest eruptions ever seen in our solar system, astronomers say.
During the three eruptions last year in August, fountains of lava more than 10,000 times as powerful as those seen during the 2010 eruption of Eyjafjallajokull in Iceland poured from vents on the moon surface, they say.
Io, heated internally from the constant stretching and pulling by the immense gravity of Jupiter, is the most volcanically active body in our solar system, and the only one other than the Earth with volcanoes that erupt with extremely hot lava.
Such outbursts, capable of ejecting material to altitudes of a hundred miles above the moon's surface, may be more commonplace than previously thought, researchers say.
"We typically expect one huge outburst every one or two years, and they're usually not this bright," says astronomer Imke de Pater at the University of California, Berkeley.
"Here we had three extremely bright outbursts, which suggest that if we looked more frequently we might see many more of them on Io."
De Pater is lead author of one of two studies on the eruptions to be published in the journal Icarus.
Researchers studied the three eruptions, the most powerful occurring on Aug. 29, 2013, using several telescopes in Hawaii.
"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," says study co-author Ashley Davies of NASA's Jet Propulstion Laboratory in Pasadena, Calif.
The brightest of them, at a volcanic caldera known as Rarog Patera, is estimated to have created a 30-foot-thick lava flow covering 50 square miles.
Volcanoes on Io were first detected in 1979, and since then studies by telescopes on Earth and by space probes visiting Jupiter and its moons have seen constant eruptions creating lakes and rivers of lava.
The kinds of eruptions of massive lava fountains seen there are probably similar to the types of volcanic activity that helped shape surfaces of the solar system's inner planets, including Earth and Venus, during their early periods of formation, astronomers say.
"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 says.
