Actually, way less often than that.
That's how often we have a full moon, total lunar eclipse, and a winter solstice, all on the same date. According to SpaceWeather.com: "there is only one previous instance, since the year 1 AD, of an eclipse matching the same calendar date as the solstice, and that was on Dec 21, 1638. Fortunately we won't have to wait 372 years for the next one...that will be on Dec. 21, 2094."
And two days from now, December 21st, 2010, it all comes together once again, for a celestial show that will probably be obscured by clouds here in Hood River. However, that doesn't stop this extremely rare event from happening in our lifetimes, even if the visual part is behind clouds. We'll just have to use our vivid imaginations, watch it live or recorded on the internet, or check out Shadow And Substance, which does an excellent job of animating these sorts of cool happenings in the sky.
But really, the best part of this event: It's the gift that keeps on giving. From Dec 22nd on, the daylight hours start to get longer and longer.
So, Merry Christmas to y'all, and to all, a shorter night!
(unless you live in the Southern Hemisphere, in which case, never mind about the shorter nights)
Florida?? Merry Christmas from Hawaii, courtesy of Jimmy Buffett