What Causes The Phases Of The Moon?

What causes the phases of the moon? The common incorrect answer is the shadow of the Earth. The phases of the moon are actually just a result of our perception of the moon's half-illuminated surface. When the moon does pass through Earth's shadow the result is a lunar eclipse. This can be spectacular as the moon turns a deep shade of red.

Images courtesy of NASAimages.org and Geoff Wyatt, Senior Astronomy Educator Powerhouse Museum