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What Do Moon Phases Represent?

The eight phases of the moon represent the percentage of the moon that appears illuminated from the Earth. Earth's gravity pulls on the moon and keeps it in orbit. As the moon orbits the Earth, observers on the Earth see different views of the sunlit and dark sides of the moon. These changing views result in the moon appearing in various stages of light and darkness that are called phases.

New Moon
- A new moon occurs when the Earth is facing the dark side of the moon.
Waxing Moons
- As the moon changes phase from new to full, it is said to be waxing. Between the new moon and the first-quarter moon, the moon appears mostly dark and is said to be a waxing crescent moon. Between the first-quarter moon and the full moon, the moon appears mostly full and is called a waxing gibbous moon.
First-quarter Moon
- Half-way between the new moon and full moon is the first-quarter moon. Half of the moon appears lit, while the other half appears dark.
Full Moon
- When the moon passes behind the Earth in relation to the sun, the moon appears fully lit.
Waning Moons
- After a full moon, the moon begins to recede into darkness as the phases slowly progress toward the next new moon. Between the full moon and the third-quarter moon, the moon appears mostly full and is known as a waning gibbous moon. Between the third-quarter moon and the new moon, the moon appears mostly dark and is called a waning crescent moon.
Third-quarter Moon
- When the moon is half-way through the waning phase, it again appears to be half-lit. This is the third-quarter moon. Note that the side that appears lit in the third-quarter moon is opposite from the side that appears lit in the first-quarter moon.

Astronomy