Monday, December 20, 2010

Monday night's lunar eclipse

Clouds may obscure view of Monday night

A total eclipse of the moon Monday night will coincide with winter solstice, which means the moon will appear high in the sky and be visible throughout all of North and Central America, including Seattle — weather permitting.

Starting around 10:33 p.m. PST, the full moon, normally illuminated by the sun, will pass through the shadow, or umbra, created by Earth blocking the sun's light.

Some indirect sunlight still will manage to pierce through and give the moon a ghostly color — brown or maybe deep red rather than the usual orange-yellow tinge, thanks to recent volcanic eruptions that have dumped tons of dust into the atmosphere.

The sky will darken as the shadow progresses across the moon, and more stars will appear in the sky as sunlight reflected from the moon fades.

The forecast for the Seattle area is for mostly cloudy skies, with showers.

Unlike a total solar eclipse, when the sun is blotted out, a lunar eclipse rarely turns the moon totally black. Because of sunrises and sunsets that scatter and refract light from the sun around the world, the moon generally appears bright and coppery orange, or sometimes brown or dark red-black, depending on how much pollution is in the atmosphere.

The most recent total eclipse of the moon was on the night of Feb. 20-21, 2008.

Totality will last a generous 72 minutes, and the process then will reverse, with the moon completely emerging from the umbra at 2:01 a.m. Tuesday.

"It's perfectly placed so that all of North America can see it," said eclipse expert Fred Espenak of NASA's Goddard Space Flight Center.

Also unlike a solar eclipse, which generally can be seen only from selected places on Earth, a lunar eclipse can be seen from anywhere on the side of the planet facing the moon.

The next lunar eclipse will be on June 15, but North America will miss out because the continent will be facing the wrong way. Another eclipse will occur Dec. 10 but will be interrupted by moonset and sunrise.

The next total lunar eclipse for the entire continent won't occur until April 14-15, 2014, an unusually long wait.


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