The full moon appearing on December 21st will occur on the same date as the the winter solstice north of the equator, and the summer solstice to the south of it. Here in the northern hemisphere, that means the longest night of the year, and the official start of winter -- and of course, this is all taking place during the holiday season!
However, this year there is even more cause for celebration, or at least observation, as a full lunar eclipse will coincide with the solstice for the first time in 372 years. According to NASA:
Geoff Chester of the US Naval Observatory inspected a list of eclipses going back 2000 years. "Since Year 1, I can only find one previous instance of an eclipse matching the same calendar date as the solstice, and that is 1638 DEC 21," says Chester.
For folks in North America the entire eclipse will be visible across the continent, starting early Tuesday morning at 1:33 a.m. EST / 10:33 p.m. PST. According to this map from NASA, it looks like the eclipse will be visible at least partially in Western Europe, Latin America, Northwest Africa and the Far East.
Lunar eclipses are safe to watch with the naked eye, so it will be possible to see the moon change colors, from white to orange, and then, due to ash particles from this past year's volcano eruptions in Iceland and Indonesia, to a deep red.
There won't be another combined lunar eclipse/solstice until December 21, 2094, so people all over the world will be observing and or celebrating this double whammy event on this long, dark night.
What will you be doing?