All topics

Tidal locking

Tidal locking occurs when an object like a moon reaches a state where it no longer changes its rotation rate over a complete orbit. The most famous example is Earth's Moon: the same side always faces Earth because it takes the same time to rotate as it does to orbit. This happens because gravity from the larger body pulls harder on the near side than the far side, creating stretching effects called tidal bulges. Over millions of years, these bulges cause friction that gradually slows the smaller body's rotation until it matches its orbital period, preventing the body from changing its rotation rate anymore.

Sources

• en.wikipedia.org: “Tidal locking between a pair of co-orbiting astronomical bodies occurs when one of the bodies reaches a state where there is no longer any net change in its rotation rate over the course of a complete orbit.”
• en.wikipedia.org: “For example, the same side of the Moon always faces Earth, although there is some variability because the Moon's orbit is not perfectly circular.”
• en.wikipedia.org: “The effect arises between two bodies when their gravitational interaction slows a body's rotation until it becomes tidally locked. Over many millions of years, the interaction forces changes to their orbits and rotation rates, as a result of energy exchange and heat dissipation.”