How gravity synchronizes a moon's rotation with its orbit — why we only see one face of the Moon
Spin Period—
Orbital Period—
Torque—
Lock Ratio—
The tidal bulge raised on the moon by the planet's gravity is dragged slightly ahead (or behind) the line of centers by friction. This misalignment creates a torque that gradually slows (or speeds) rotation until spin = orbital frequency. All large moons in our solar system are tidally locked.