A titanic volcanic eruption has been spotted on the surface of Jupiter鈥檚 volatile moon Io using a telescope back on Earth. Astronomers believe it to be the most powerful eruption ever witnessed in the entire Solar System.
The volcano spewed lava kilometres into the sky during its most explosive period, say the researchers. The consequent lava flow is thought to have spread many hundreds of square kilometres across the surface of Io.
鈥淚t is clear that this eruption is the most energetic ever seen, both on Io and on Earth,鈥� says Franck Marchis, a researcher at the University of California, Berkeley, who analysed the images.
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The eruption was recorded in February 2001 during routine monitoring of Io鈥檚 volcanic activity by a telescope at the Keck Observatory in Hawaii. But the images were only recently analysed.
Fire fountains
Ashley Davies, at NASA鈥檚 Jet Propulsion Laboratory, in California, adds: 鈥淭he kind of eruption to produce this thermal signature has incandescent fire fountains of molten lava which are kilometres high. They are propelled at great speed out of the ground by expanding gases, accompanied by extensive lava flows on the surface.鈥�
The images were produced using three wavelengths of mid-infrared light. The researchers also used a technique called adaptive optics to automatically correct visual distortions caused by the Earth鈥檚 atmosphere. This process has made it possible for Earth-based telescopes to produce images that could previously only have come from space-based instruments.
The technique meant the captured images had a resolution of about 100 metres per pixel. This is similar to the quality of photographs produced by NASA鈥檚 probe Galileo, which is orbiting Jupiter.
Big wattage
The volcano is far more powerful than any eruption recorded by scientists on Earth, with an estimated power output of about 78,000 gigawatts. By comparison, the power produced by the last significant eruption of Mount Etna in Italy in 1992 was just 12 gigawatts.
But geological records indicate that there may have been some comparably large eruptions many millions of years ago, in India and Siberia for example.
The observations will also help reveal more about the nature of Io, says Lionel Wilson at the Planetary Science Research Group at Lancaster University, UK.
鈥淭hese results may be the first to allow us to make a good estimate of the volume eruption rate of lava on Io in a large volume eruption with a high eruption rate,鈥� he says. 鈥淏uilding up statistics on the range of eruption conditions that can occur on Io will allow us to deduce much more about the structure of the crust and mantle than we understand at the moment.鈥�
Journal reference: Icarus (DOI:10.1006/icar.2002.6955)