Io is one of the moons of which planet?
Io (moon) Io (moon) Io (Jupiter I) is the innermost of the four Galilean moons of the planet Jupiter. It is the fourth-largest moon, has the highest density of all the moons, and has the least amount of water of any known astronomical object in the Solar System. It was discovered in 1610 and was named after the mythological character Io, a priestess of Hera who became one of Zeus' lovers. With over 400 active volcanoes, Io is the most geologically active object in the Solar System. This extreme geologic activity is the result of tidal heating from friction generated within Io's
Io Volcano Observer 1" in March 1979. This significant amount of volcanism on Io is the result of tidal heating, a process that has also resulted in increased internal heat within other outer planet satellites, such as Enceladus and Europa. On both of these latter moons, the tidal heating has allowed liquid water near the surface of these moons, dramatically affecting their geology and providing a possible habitat for life. Since its discovery in 1979, the volcanic activity on Io was observed by ground-based astronomers as well as the Galileo, Cassini and New Horizons spacecraft. Galileo flew by Io seven times over the