Jupiter's ocean moons capture most of our attention because of their potential habitability. But Io, Jupiter's bad-boy volcanic moon, is in a class of its own. There's nothing else like it in the solar system, and NASA's ...
Io is Jupiter's third-largest moon and the solar system's fourth largest moon. It's also larger than our moon. It has the highest density and the strongest gravity of any moon. Io also has the least amount of water of any astronomical object in the solar system.
Those characteristics alone make it interesting. But what really garners Io so much attention, and led Juno to study it more closely, is its volcanic activity. It's the most geologically-active body in the solar system and boasts over 400 volcanoes, along with widespread lava flows.
Juno's JunoCam instrument captured new images of Io from its closest approach yet on October 15th, from less than 12,000 km away. Now, citizen scientists have processed these images and shared them with the rest of us. The result is the best images of Io we've seen since the Galileo mission ended 20 years ago.
We have NASA's foresight to thank for these images. When they were planning the Juno mission, they found room for JunoCam. JunoCam is primarily a public engagement instrument, though it does help provide context for the spacecraft's more rigorous science instruments. The camera was intended to capture images for citizen scientists and other skilled—or amateur—image processors to have fun with.
Not since the Galileo mission ended 20 years ago have we seen such great images of Io. NASA's Juno spacecraft captured this image with its JunoCam instrument on October 15th from less than 12,000 km altitude. Ted Stryk processed the image. Credit: Ted Stryk/NASA/JPL-Caltech/SwRI/MSSS/
These Galileo images show two different episodes of volcanic eruptions and their plumes. The image on the left shows two plumes, one in blue on the moon’s limb, and a more difficult to see one in the center near the terminator line. The image on the right shows another eruption from Pillan Patera in 1997 as the expanding red circle with the dark spot in the center. Credit: (L) NASA’s Galileo spacecraft, public domain. (R) NASA/JPL