- Image of Io Taken by NASA's Galileo Spacecraft - NASA
Io is the most volcanically active body in the Solar System. Regular volcanic eruptions on Io dwarf even large infrequent eruptions here on Earth. Scientists believe current geologic activity on Io may be an adequate representation of what the first few hundred million years on Earth looked like. This makes studying Io an important part in developing theories for how continents and oceans evolved on Earth.
Volcanoes on Io and Tidal Heating
Io, Jupiter's third largest moon, only a bit larger than the Earth's moon, has the largest active volcanoes in the Solar System. Here on Earth, these volcanoes would be called "supervolcanoes". The source of volcanism on Io is very similar to one of the sources of volcanism here on Earth, except on a much larger scale. Io's intense volcanism is due to the tidal heating of the moon.
Tidal heating is one outcome of tidal forces that result from the gravitational pull of close bodies. For example, here on Earth, the gravitation pull of the Moon creates tides in the oceans. The tidal force of the Moon is so strong, that in some places on Earth the difference between high tide and low tide is as much as 18 meters (60 feet). These tidal forces also generate friction, which causes heat. Tidal heating is a source of heat for Earth's volcanism, but it is nothing compared to the tidal heating experienced by Io.
Io experiences tidal heating from its close proximity to the large planet Jupiter and other nearby moons. The result of these forces not only heat up Io for volcanism, they also tug and pull at Io's crust. Just like Earth's oceans rise and fall due to tidal energy, Io's crust also has high and low tides. Except on Io, the gravitation forces cause the crust to bulge up to 100 meters (300 feet) in some places. This extreme tugging and pulling on the crust also keeps it very plastic and easy to remelt. So there is a constant recycling of Io's crust, which adds to the volcanic activity.
The Biggest Recorded Volcanic Eruption in the Solar System
On March 1, 2007, NASA's New Horizon satellite, on its way to Pluto, passed by Io close enough to observe a supervolcano eruption as it was happening. The volcano on Io, named Tvashtar Volcano, was sending a plume 330 kilometers (200 miles) above the moon's surface. The plume was easily seen by the New Horizons camera, which took several pictures over an 8-minute time span in which the fallout of the plume can be seen.
Although this volcanic eruption is very large, even by Io's standards, eruptions that send plumes hundreds of kilometers above the surface are a regularity for Io. Eruptions this large happen very infrequently on Earth, which is a good thing because they have been known to cause mass extinctions and change the climate. However, scientists believe that this type of volcanic activity and frequent crustal recycling may have been very common immediately following Earth's formation.
Source:
"Solar System Exploration: Io", nasa.gov
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Alexandra Matiella Novak - With a PhD in Geology and expertise in science education, Alexandra is passionate about increasing the public's Earth science literacy.
