Heads Up - There's a Lunar Eclipse Tonight

[Calyx]

Introduction

A total eclipse of the Moon occurs during the early morning of Tuesday, August 28, 2007. The event is widely visible from the United States and Canada as well as South America, the Pacific Ocean, western Asia and Australia. During a total lunar eclipse, the Moon's disk can take on a dramatically colorful appearance from bright orange to blood red to dark brown and (rarely) very dark gray.


An eclipse of the Moon can only take place at Full Moon, and only if the Moon passes through some portion of Earth's shadow. The shadow is actually composed of two cone-shaped parts, one nested inside the other. The outer shadow or penumbra is a zone where Earth blocks some (but not all) of the Sun's rays. In contrast, the inner shadow or umbra is a region where Earth blocks all direct sunlight from reaching the Moon.



More here, including diagrams:
NASA - Total Lunar Eclipse: August 28, 2007