A moon raises tides on the planet it orbits. Because of internal friction, the maximum tide height lags the applied force and the bulges are displaced. Tidal torques on bulges oppose and slow down rotation on the moon (until it becomes tidally locked) and the planet When rotation of the planet slows, angular momentum is conserved and the orbital radius of the satellite increases for a prograde satellite, but decreases for a retrograde satellite.
Tidal Acceleration, Tidal Heating, Tide
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