Asked by: Dennis Lund, Salisbury
Tidal locking is the phenomenon by which a body has the same rotational period as its orbital period around a partner. So, the Moon is tidally locked to the Earth because it rotates in exactly the same time as it takes to orbit the Earth. That is why we only see one side of the Moon. If both bodies are of comparable size and are close together, both bodies can be tidally locked to each other – this is the case in the Pluto-Charon system.
Tidal locking is a natural consequence of the gravitational distortions induced by a body on another.