Tidal flexing of Io

Tidal flexing of Io

Fig. 9.15 . Due to an orbital resonance with nearby Europa, Jupiterís satellite Io has a noncircular orbit. The forced eccentricity makes Io travel at different speeds along its orbit and the side facing Jupiter nods back and forth slightly, as seen from the planet. Although only half a degree in extent, this movement causes varying tidal forces inside the satellite, flexing it in and out like squeezing an exercise ball with your hand. This, in turn, generates internal friction and heat, leading to the active volcanoes seen on Io with instruments aboard the Voyager 1 and 2 and Galileo spacecraft. In this drawing, Ioís size and the eccentricity of its orbit are exaggerated when compared with Jupiter.

Copyright 2010, Professor Kenneth R. Lang, Tufts University