the volcanology of io, a moon of jupiter, is the scientific study of lava flows, volcanic pits, and volcanism (volcanic activity) on the surface of io. its volcanic activity was discovered in 1979 by "voyager 1" imaging scientist linda morabito. observations of io by passing spacecraft (the "voyagers", "galileo", "cassini", and "new horizons") and earth-based astronomers have revealed more than 150 active volcanoes. up to 400 such volcanoes are predicted to exist based on these observations. io's volcanism makes the satellite one of only four known currently volcanically active worlds in the solar system (the other three being earth, saturn's moon enceladus, and neptune's moon triton).