Wednesday, February 20, 2008

Lunar Eclipse

A total lunar eclipse is set to occurr tonight. Here's some information from NASA's Eclipse website.

A total eclipse of the Moon occurs during the night of Wednesday, February 20/21, 2008. The entire event is visible from South America and most of North America (on Feb. 20) as well as Western Europe, Africa, and western Asia (on Feb. 21). 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.
If only part of the Moon passes through the umbra, a partial eclipse is seen. However, if the entire Moon passes through the umbral shadow, then a total eclipse of the Moon occurs.