Science · 6 pages · 12 min
Why the same side of a tide-locked moon faces its planet
Tidal torques slow a moon until one face stays toward its planet.
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From the opening
A tide-locked moon keeps one face toward its planet because tidal torques have matched its spin to its orbital period. The inward face stays inward on average, which is the stable way for a slightly stretched body to ride in that gravity. The opening covers how an offset bulge brakes spin, why the matched state stays put, and which other moons are locked.
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Inside
- How an offset bulge brakes spin
- Why the matched state stays put
- Which other moons are locked
- When a moon tumbles instead
- Where the idea stops applying
- A distinction worth keeping
Sources
- Tidal locking and synchronous rotation
- Chaotic rotation of Saturn's moon Hyperion