I'm a little late getting the word out, but there will be a total lunar eclipse visible to all of North America on Tuesday morning, December 21, 2010! It will run from about 12:30 a.m. ET (that's just after Midnight, folks) Tuesday morning (or Monday night, as some people might refer to it) to about 6 a.m. ET.
The important thing about this eclipse is that it will be the first total lunar eclipse to occur on the Winter Solstice since 1683, and only the second one to occur in the Common Era! So if you have reasonably clear skies, Don't miss it!!
Here's an animated gif file from Wikipedia that demonstrates what will happen.
And in case that didn't work for you or it doesn't animate, then here's a video of it that I made using my Starry Night program. Be warned: in case the Moon isn't round in the video below, You know that it really is, right? My first try with this made the Moon look like an egg. But you get the idea, right? :-) [UPDATE edit: I think it's fixed now]
There are two shadows cast by the Earth that the Moon will pass through: first the penumbra, and then the Umbra. Now, you may not notice much at the start of the eclipse when the Moon enters the penumbra. It's only a partial shadow and you'll only see the Moon dim a bit. But when the Moon enters the Umbra, then it will be fully within the darkest part of the Earth's shadow.
Note that the Moon will not go completely dark as my video implies! Instead, it will most probably turn a dark ruddy orange or red. This is for the same reason that you see red/orange sunrises and sunsets. The Earth's atmosphere bends some of the sun's light around the Earth and into the shadow.
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