Io: A guide to Jupiter’s volcanic moon

Io — Jupiter’s fifth moon — is the most volcanically active body in the solar system. Io’s surface is peppered with hundreds of volcanoes, some spewing sulfurous plumes hundreds of miles high. 

The volcanic moon is Jupiter’s third-largest and the innermost Galilean satellite, it finds itself caught in a gravitational tug-of-war between Jupiter and two nearby Jovian moons Europa and Ganymede. These tidal forces generate the heat that drives Io’s intense volcanic activity, according to NASA.