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  3. Moon Phases
Observational Astronomy

Moon Phases

Definition

The different appearances of the Moon over a synodic month (about 29.5 days). The eight phases are new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent, caused by changing Sun-Moon-Earth angles.

Related Terms

Eclipse

An astronomical event when one celestial body moves into the shadow of another. Solar eclipses occur when the Moon passe...

Orbit

The curved path of a celestial object around a star, planet, or moon under gravity's influence. Orbits can be circular, ...

Tidal Forces

Gravitational forces arising because gravitational pull varies across a body's extent. On Earth, the Moon and Sun cause ...

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