Quirks & Quarks

Why does Jupiter's moon Io have volcanoes but our moon doesn't?

Jupiter's powerful gravity creates tidal friction that drives Io's volcanoes

Jupiter's powerful gravity creates tidal friction that drives Io's volcanoes

An erupting volcano on Io, as seen by NASA’s Galileo spacecraft in November 1997 (NASA/JPL/University of Arizona)

Richard Buettner of Regina asks: 

Why do volcanoes currently exist on Jupiter's moon, Io, and not on Earth's moon? What other kinds of phenomena/effects can occur on moons due to this pull of gravity?

According to Dr. Catherine Johnson, a planetary scientist at the University of British Columbia, the difference has to do with the relative difference between the mass of the planets that Io and the Moon orbit.

Both moons are of similar size and orbit at a similar distance from their planets.

The Earth and the Moon raise tides on each other due to their gravitational attraction. The Earth's tides manifest most obviously in our oceans, but there is tidal force on the land as well. Similarly the Earth raises tides on the Moon. Moon-quakes first measured by the Apollo astronauts have been attributed to these tides. 

The tides that Jupiter raises on Io, however are powerful enough to induce sufficient friction in that moon's rocks, melting and volcanoes can result. 

A similar phenomenon produces ice volcanoes on Saturn's moon, Enceladus. 

Written and produced by Jim Lebans

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