Tidal locking
![Tidal locking results in the Moon rotating about its axis in about the same time it takes to orbit Earth. Except for libration effects, this results in the Moon keeping the same face turned toward Earth, as seen in the figure on the left. (The Moon is shown in polar view, and is not drawn to scale.) If the Moon were not rotating at all, it would alternately show its near and far sides to Earth, while moving around Earth in orbit, as shown in the figure on the right.](/Images/godic/202501/03/Tidal_locking_of_the_Moon_with_the_Earth4748.gif")
![If the tidal bulges of a body are misaligned with the major axis, the tidal forces exert a net torque on that body that twists the body toward the direction of realignment](/Images/godic/202501/03/Árapály_forgatónyomaték4748.png")
![If rotational frequency is larger than orbital frequency, a small torque counteracting the rotation arises, eventually locking the frequencies (situation depicted in green)](/Images/godic/202501/03/MoonTorque4748.jpg")
![Due to tidal locking, the inhabitants of the central body will never be able to see the satellite's green area.](/Images/godic/202501/03/Synchronous_rotation.svg4748.png")
Tidal locking (also called gravitational locking or captured rotation) occurs when the gravitational gradient makes one hemisphere of a revolving astronomical body constantly face the partner body. This effect is known as synchronous rotation. A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. For example, the same side of the Moon always faces the Earth. Usually, only the satellite is tidally locked to the larger body. However, if both the mass difference between the two bodies and the distance between them are relatively small, each may be tidally locked to the other; this is the case for Pluto and Charon. This effect is employed to stabilize some artificial satellites.