Here's why we see a lighted moon at different stages:
* The moon doesn't produce its own light. It shines because sunlight reflects off its surface.
* The moon orbits Earth. As it orbits, the angle at which we see the sunlit portion of the moon changes.
* The phases:
* New Moon: The moon is between the sun and Earth, so we see the dark side.
* Waxing Crescent: A sliver of the moon becomes visible, getting larger each night.
* First Quarter: Half the moon is illuminated.
* Waxing Gibbous: More than half the moon is lit, growing fuller.
* Full Moon: The entire sunlit side faces Earth.
* Waning Gibbous: The moon appears full, but starts to shrink.
* Last Quarter: Again, half the moon is illuminated, but now the other half.
* Waning Crescent: The illuminated sliver gets smaller until it disappears.
So, the lighted moon you see is simply the portion of the moon reflecting sunlight that is visible from Earth at that moment in its orbit.
