<P> 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). </P> <P> First predicted shortly before the Voyager 1 flyby, the heat source for Io's volcanism comes from tidal heating produced by its forced orbital eccentricity . This differs from Earth's internal heating, which is derived primarily from radioactive isotope decay and primordial heat of accretion . Io's eccentric orbit leads to a slight difference in Jupiter's gravitational pull on the satellite between its closest and farthest points on its orbit, causing a varying tidal bulge . This variation in the shape of Io causes frictional heating in its interior . Without this tidal heating, Io might have been similar to the Moon, a world of similar size and mass, geologically dead and covered with numerous impact craters . </P> <P> Io's volcanism has led to the formation of hundreds of volcanic centres and extensive lava formations, making it the most volcanically active body in the Solar System . Three different types of volcanic eruptions have been identified, differing in duration, intensity, lava effusion rate, and whether the eruption occurs within a volcanic pit (known as a patera). Lava flows on Io, tens or hundreds of kilometres long, have primarily basaltic composition, similar to lavas seen on Earth at shield volcanoes such as Kīlauea in Hawaii . Although most of the lava on Io is made of basalt, a few lava flows consisting of sulfur and sulfur dioxide have been seen . In addition, eruption temperatures as high as 1,600 K (1,300 ° C; 2,400 ° F) were detected, which can be explained by the eruption of high - temperature ultramafic silicate lavas . </P>

What is the cause of volcanic activity on jupiter's moon io