December 21, 2010 is the winter solstice this year, the shortest day of the year, and the first day of winter.
the moon will be full.
In the early morning, the full moon will be passing directly through the northern half of the darkest part of the Earth's shadow (the umbra), i.e., a full lunar eclipse will be visible to almost all of North America!
The eclipse starts at 12:30 AM Eastern Standard Time (Tuesday morning). That's when the moon enters the Earth's penumbra. You won't see anything too exciting, though, until 1:32 AM Eastern, when the moon begins entering the darker umbra. The moon's disc will look like a bite has been taken out of it, and as the bite increases in size the moon will change color, from white to either a coppery color (if you have clean skies) to dark red (if you have dusty, dirty skies).
The moon should be fully eclipsed between 2:40 AM and 3:53 AM Eastern time.
if you want to run out and see just the best parts, I like when the total eclipse first starts (at 2:40 AM Eastern, 1:40 AM Central, 12:40 AM Arizona); the first little nibble out of the moon looks very trippy, and you almost can't tell if it's an optical illusion or not. And then the time of greatest eclipse is 3:16 AM Eastern time (2:16 AM Central, 1:16 AM in Arizona).