3.12 Investigating orbital resonance
In the ‘Tidal heating explained’ video you saw that Io completes two orbits of Jupiter in the time that it takes Europa to make one orbit. This ‘orbital resonance’ is what prevents the moon’s orbits from becoming circular, which means that tidal forces continually distort, and heat, their interiors.
In the Jupiter system, it is not just Io and Europa that share a resonance. The next moon out, Ganymede completes one orbit in the time that it takes Europa to complete two orbits, during which time of course Io will have completed four orbits. This is a ‘4:2:1 orbital resonance’ relationship between Io, Europa and Ganymede. The animation here demonstrates this relationship.
Download this video clip.Video player: moons_1_vid015.mp4
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