Jupiter's moon Io doesn't get as much attention as potential life-sustaining moon Europa, but it still has its own extraordinary features, including a high amount of volcanic activity that may eventually help us understand volcanoes on Earth.
It wasn't until 1979 that we learned of Io's volcanic activity after the Voyager 1 spacecraft took photos of Io that showed a moon covered in active volcanoes. However, it wasn't until recently that we understood just how active these volcanoes are.
Io is the closest of four moons to Jupiter and is about the same size of Earth's moon. It is also the only other known place in the solar system that has volcanic activity.
In August 2013, scientists used information gathered from the Voyager and Galileo probes about Io's volcanic activity. That, combined with data from Earth-based telescopes, painted a surprising picture of the moon: its volcanoes are far more active than we ever thought.
"We typically expect one huge outburst every one or two years, and they're usually not this bright," says Imke de Pater, co-author of the recent study on Io.
Data is limited as we've never closely monitored Io, but this information, including levels of brightness on the moon, offers some new and interesting facts. Scientists now suggest that these volcanic events occur when cracks form on Io's surface, which blast hot lava from inside the moon. Because of Io's low gravity, those blasts reach higher than anything we've seen on Earth.
Io is also more active than initially believed. Originally, scientists thought that only one major eruption happened there every two years, but that idea came from very limited observations of the moon. However, scientists found that the new data shows three eruptions just within a two-week period, dramatically more than they expected. The third eruption alone was brighter than anything previously observed in our solar system.
Scientists believe that the volcanic activity on Io is caused by the pull of tides from Jupiter. This heats up Io's interior, making its inside melt into liquid.
Unfortunately, no one is currently planning missions for taking a closer look at Io. Scientists, however, believe such missions are now warranted. The volcanoes on Io might give us a better idea of how volcanic activity affected Earth's early history.
"Large lava flows have shaped the surfaces of Venus, Mars and the Moon, but no one has ever seen them erupt, so there's a lot of uncertainty about the mechanism," says de Pater. "Now we're getting some vivid insight into a process that once shaped the surface of the Earth."
