* The Moon doesn't produce its own light. It reflects sunlight.

* The Moon orbits the Earth. This orbit takes about 27.3 days.

* The Sun illuminates half of the Moon. This half is always lit, but we only see different amounts of the lit half from Earth as the Moon orbits.

Here's how the phases work:

1. New Moon: The Moon is between the Earth and the Sun. We see none of the illuminated side.

2. Waxing Crescent: We start to see a sliver of the illuminated side as the Moon moves away from the Sun.

3. First Quarter: We see half of the illuminated side, looking like a half-circle.

4. Waxing Gibbous: More than half of the illuminated side is visible.

5. Full Moon: The entire illuminated side of the Moon faces Earth.

6. Waning Gibbous: We see less than half of the illuminated side, as the Moon continues its orbit.

7. Last Quarter: We again see half of the illuminated side, but now it looks like a backwards half-circle.

8. Waning Crescent: Only a sliver of the illuminated side is visible.

The cycle then repeats itself!