The full Moon will briefly hide in Earth's shadow on the night of December 20/21 during a total lunar eclipse. When fully immersed in the shadow, the Moon will look dark gray or reddish-orange. [Tim Jones]
For eclipse fans here in North America, the last couple of years have been duds. But the Moon and Sun get their act together tonight to create a total lunar eclipse. It's visible from all of North America and most of the eastern Pacific Ocean, including Hawaii.
The eclipse gets underway in earnest at 12:32 a.m. Central Time, when the dark inner portion of Earth's shadow first touches the lunar disk. The Moon will be completely immersed by 1:41, and will remain fully in the shadow for more than an hour.
As the Moon dives into the shadow, its face will turn dark red or gray. The color depends on the amount of particles in Earth's upper atmosphere. It also depends on the viewer's eyesight: Some people are more sensitive to low light levels, so they see more color than others do.
Lunar eclipses occur only at full Moon, but not every full Moon. That's because the Moon's orbit around Earth is tilted a bit with respect to the ecliptic -- the Sun's path across the sky. Most months, the Moon passes a little above or below the shadow, so it remains bright. But when the geometry is just right, the Moon crosses the ecliptic at the same time it's full -- as it does tonight -- creating a rare and beautiful show.
And as a bonus, the full Moon of December is the Long Night Moon -- it remains above the horizon longer than any other full Moon of the year. So whether it's bright or dark, enjoy the full Moon.
Script by Damond Benningfield, Copyright 2010
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