Moonrise Moment

Orbit glossary

What is tidal locking?

Tidal Locking is the long-term gravitational process that synchronized the Moon's rotation with its orbit, leaving nearly the same side facing Earth.

Earth and the Moon shown at two points along an elliptical lunar orbit.
A visual guide to tidal locking. Original Moonrise Moment illustration.

What it means

Tidal Locking describes part of the Moon's motion or position in space. The Moon follows a slightly elliptical, tilted orbit, so its distance, apparent path, rise time, and alignment with the Sun change continuously. These orbital relationships explain many patterns that observers notice from night to night.

Keep exploring

Orbit Synchronous Rotation

Rotation in which a body's spin period matches its orbital period, causing the same hemisphere to face the object it orbits.

 Orbit Apogee

The point in the Moon's orbit where it is farthest from Earth.

 Orbit Declination

A celestial coordinate comparable to latitude on Earth. It measures angular distance north or south of the celestial equator.

 Orbit Ecliptic

The Sun's apparent yearly path across Earth's sky. The Moon and planets remain near this path because their orbits have relatively small tilts.

Sources and further reading

This definition was written in plain language and checked against these science references.

Moonrise Moment showing the live direction and countdown screen.

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