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Why are there active volcanos on Io?

I am a 8th grade student and I was wondering why there are active volcanoes on Jupiter's moon Io.

The volcanic activity on Io is mostly caused by the pull of Jupiter on Io. Just like Earth's moon gravitationally attracts the oceans, causing tides, Jupiter pulls on Io. Because the pull of gravity is dependent upon the distance between masses, Jupiter pulls more on the side of Io that is closer to it than on the farther side, stretching Io out to a sort of egg-shape. Io's orbit is elliptical, so sometimes it is closer to Jupiter than others. Its elliptical orbit is further perturbed by Europa and Ganymede, two of Jupiter's other large moons. Because of this, Io's surface bulges up and down by as much as 100 meters. These tidal forces provide the energy that fuels Io's volcanos. For more information on Io, check out these webpages:

Io link 1

Io link 2

July 2003, Cathy Jordan (more by Cathy Jordan) (Like this Answer)

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