The Large Binocular Telescope on Mount Graham, Arizona has taken the highest resolution image ever from Earth of Io, the most volcanic world in the solar system.
About the same diameter as Earth’s moon, the innermost of Jupiter’s four giant moons is covered in volcanoes, some emitting sulfurous plumes hundreds of miles into space.
It’s been imaged by spacecraft—notably by NASA’s Juno in recent months—but this is the best-ever image using an Earth-based instrument.
Frictional Heat
Io is volcanic because of the gravitational pull of Jupiter and three of its other largest moons—Europa, Ganymede and Callisto—which causes the moon to be tugged in different directions during its orbit. The frictional heat buildup in its interior causes constant and widespread volcanic activity. Scientists think there’s an ocean of magma under its rocky surface.
Io, which orbits Jupiter every 42 hours, was imaged by the only binocular telescope of its kind. Equipped with two 27-foot mirrors mounted side by side, ir was able to reveal features as small as 50 miles across, a spatial resolution that until now had been achievable only with spacecraft in orbit of the giant planet.
Spewing Lava
Published this week in the Geophysical Research Letters, the images captured three of Io’s most prominent features—the volcano Pele (below and to the right of the moon’s center), the white ring around the Pillan Patera volcano (to the right of Pele) and Io’s largest volcano, Loki Patera (left).
The image is so detailed that researchers were able to spot a change in Io’s surface where Pillan Patera is spewing lava onto Pele’s surroundings. “We interpret the changes as dark lava deposits and white sulfur dioxide deposits originating from an eruption at Pillan Patera, which partially cover Pele’s red, sulfur-rich plume deposit,” said Ashley Davies, co-author of the paper and a principal scientist at NASA’s Jet Propulsion Laboratory.
Such events have proven impossible to imagine from Earth before. The breakthrough is SHARK-VIS, a new high-contrast optical imaging instrument fitted to the telescope, which already has a cutting-edge adaptive optics system to compensate for the blurring caused by turbulence in Earth’s atmosphere.
In October last year, during its 55th close flyby of the planet, Juno passed 7,270 miles (11,700 kilometers) from Io, making it the closest pass since NASA’s Galileo probe imaged the volcanic moon in October 2001.
During its next close pass in December, it reached just 930 miles (1,500 kilometers) from the moon’s surface. In April this year it took more images (above) from 10,250 miles (16,500 kilometers) above the surface of Io.
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