* The moon doesn't produce its own light. It reflects sunlight.
* The moon orbits the Earth. This orbit takes about 27.3 days.
* The moon is constantly illuminated by the sun. However, as the moon orbits the Earth, the portion of the illuminated side that we see from Earth changes.
Here's how it works:
1. New Moon: The moon is between the Earth and the sun. We can't see it because the sunlit side is facing away from us.
2. Waxing Crescent: As the moon moves in its orbit, a sliver of the sunlit side starts to become visible, appearing as a crescent.
3. First Quarter: We see half of the illuminated moon, shaped like a quarter.
4. Waxing Gibbous: More than half of the illuminated side is visible, looking like a slightly fattened half-moon.
5. Full Moon: The moon is on the opposite side of the Earth from the sun, so we see the entire sunlit face.
6. Waning Gibbous: The illuminated portion starts to shrink, becoming a fattened half-moon again.
7. Last Quarter: We see half the illuminated moon again, shaped like a quarter, but the lit side is opposite from the first quarter.
8. Waning Crescent: The lit sliver continues to shrink until it disappears again, leading back to the new moon.
This cycle repeats every 29.5 days, giving us the familiar lunar phases we see in the sky.
