Jupiter has over 95 known natural satellites, or moons. But of these, most of them are small and insignificant. Not the four Galilean moons, which are visible from Earth with strong binoculars. These include Io, Europa, Ganymede, and Callisto.
NASA’s Juno spacecraft recently passed by Io, and took images of the highly active moon, which is the innermost and third-largest of the four. It has over 400 active volcanos, making it the most geologically active body in the whole solar system. This activity is caused by result of tidal heating from friction generated within Io’s interior, which explode sulfur and sulfur dioxide up to 300 miles into the moon’s atmosphere.
We can only imagine how dramatic and hostile it must be on Io’s surface.
The images below are taken on July 30 by NASA’s JunoCam, and showcase the highly active and extreme conditions on the surface of the moon.

Animation of 12 Io images acquired by JunoCam Sunday evening. Resolution of best image is 15 km/pixel. pic.twitter.com/sdA3NsKpVV
— Jason Perry (@volcanopele) August 3, 2023

