Wednesday, February 20, 2008

Today in History

Spotlight: Sky-watchers in South America, most of North America, and much of Western Europe, Africa and western Asia will be treated to a full lunar eclipse tonight. A lunar eclipse occurs at a time of a full moon, when the sun, earth and moon are lined up exactly, with the earth in the middle. The earth casts a shadow composed of two cone-shaped parts — the umbra and the penumbra, one inside the other. When the entire moon passes through the umbral shadow, a total lunar eclipse occurs. Tonight's eclipse will last about 3 1/2 hours; the total eclipse will start about 90 minutes into the event and last about 50 minutes.

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