Lunelock: Tidal Locking
Mechanics, Chaos & Fluids arc, page 106 of 193. Back to The Pixelated Physics Universe
Who they are
Lunelock has one line, and says it often: “Tidally locked to the slides.”
Lunelock is a character of the Mechanics, Chaos & Fluids arc: drawn in pixels, ruled by one piece of real physics, and never allowed to break it.
The physics
Tidal locking: tidal torque despins a satellite until rotation period equals orbital period, so it always shows the same face (as the Moon does).
$$ \begin{gathered} P_{\text{rot}} = P_{\text{orb}} \end{gathered} $$
| Symbol | Meaning | SI unit |
|---|---|---|
| $P_{\text{rot}}$ | rotation period of the satellite | s |
| $P_{\text{orb}}$ | orbital period | s |
Sources
- S. J. Peale, "Rotation histories of the natural satellites," in Planetary Satellites, ed. J. A. Burns (Univ. Arizona Press, 1977), pp. 87–112
- B. Gladman et al., Icarus 122, 166 (1996)
Crossovers
Lunelock meets Bertrande (Bertrand's Theorem). Bertrande's Kepler ellipses close because gravity goes as 1/r². Lunelock adds what pure point masses miss: tides raise bulges that slowly despin the Moon until it rotates once per orbit.
Lunelock meets Wobbleon (Chandler Wobble). Lunelock's tides despun the Moon. Wobbleon's Earth feels tides too, and its rotation is slowing; the Chandler wobble itself is kept going by forcing from the atmosphere and oceans.
Wear the lore
Concept keywords: Tidal Locking, Lunelock, Mechanics, Chaos & Fluids, physics lore, Pixelated Physics