Io (moon)
Io is the innermost of the four large Galilean satellites of Jupiter and the most volcanically active world in the Solar System, with hundreds of active volcanoes and towering sulfurous plumes. Slightly larger than Earth’s Moon, it orbits Jupiter every 1.769 days in a resonance with Europa and Ganymede, generating intense tidal heating that drives its global volcanism. Spacecraft including Voyager, Galileo, New Horizons, and Juno have revealed Io’s dynamic surface, iron core, and complex interaction with Jupiter’s magnetosphere.
