A series of three massive volcanic eruptions detected on the surface of Jupiter's moon Io in August last year, has the potential to yield insights into the formation process of the surface of Earth-like planets. By any standards, these eruptions were enormous, characterized as titanic curtains of lava issuing forth from fissures several miles in length, that spewed massive amounts of material high above the moon's surface.
"These new events are in a relatively rare class of eruptions on Io because of their size and astonishingly high thermal emission," states Ashley Davies, a volcanologist at NASA's Jet Propulsion Laboratory. "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."
The close timing of the eruptions has led astronomers to the conclusion that such events are in fact much more common than previously thought. Prior to the activity of August last year, it was believed that eruptions of this magnitude would take place on average only once every two years. This spacing was based on the fact that only 13 large eruptions had been spotted between 1978 and 2006, however this is most likely because the moon is very rarely under detailed observation.
The first two eruptions were discovered on Aug. 15, by Imke de Pater, professor and chair of astronomy at the University of California in Berkeley. The find was made using the near-infrared camera mounted on the 10-meter Keck 2 telescope, operated out of the Keck Observatory, Hawaii. The eruptions were detected in the moon's southern hemisphere, with the brightest of the two, located at the Rarog Patera caldera, estimated to have created a 50 sq mile (130 sq km) lava flow measuring 10 m (30 ft) in depth.
The final eruption was caught on Aug. 29 by both De Pater and UC Berkeley graduate Katherine de Kleer, using NASA's SpeX near-infrared spectrometer located at the agency's Infrared Telescope Facility (IRTF), and the Gemini North telescope operated out of Mauna Kea, Hawaii. This final eruption was the brightest ever recorded, and is thought to have reached temperatures much hotter than those created in the average eruption taking place back on Earth.
Io is the only other planetary body in our solar system with active volcanoes erupting lava, as is the case here on Earth. Observing this ferocious volcanic activity could be of great use in understanding the formation of our own planet's surface. "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," states Davies.
It is hoped that further study of Jupiter's innermost Galilean moon will garner further insights into the style of volcano present on Io, and the composition of its lava, thus allowing the team to create a map detailing variations in heat flow over time. From this, scientists will be able to gain a better understanding of the heating and cooling process at work on Io, and with these insights refine our perception of the tumultuous conditions that prevailed on Earth during its formative years.