On March 8, 1979, Voyager 1 discovered volcanoes on Io, one of Jupiter’s moons. These were the first active volcanoes discovered outside Earth.
Io’s volcanism is a result of tidal heating. Io has a very eccentric (or oval-shaped) orbit around Jupiter. Io’s orbital eccentricity interacts with the gravitational pull of Jupiter in such a way that the interior of Io heats up. The heat creates so much pressure that hot gases and other materials are ejected at Io’s surface: volcanoes.
Active volcanoes have been discovered on two other moons: Enceladus, a moon of Saturn, and Triton, a moon of Neptune. Io, however, is still the most volcanically active place in the solar system. (And yes, that includes Earth!)
Term Part of Speech Definition Encyclopedic Entry eject Verb
to get rid of or throw out.
state of matter with no fixed shape that will fill any container uniformly. Gas molecules are in constant, random motion.
gravitational pull Noun
physical attraction between two massive objects.
to work with or meet.
internal or inland.
largest planet in the solar system, the fifth planet from the Sun.
natural satellite of a planet.
Encyclopedic Entry: moon pressure Noun
force pressed on an object by another object or condition, such as gravity.
an opening in the Earth's crust, through which lava, ash, and gases erupt, and also the cone built by eruptions.
Encyclopedic Entry: Plate Tectonics and Volcanic Activity