Once in a blue moon

It's New Year's Eve which is a singular enough occasion, but this New Year's Eve is even more rare.

Tonight is the night of the blue moon. The last time there was a blue moon on New Year's Eve was in 1990, and there won't be another for 19 more years.

No, it's not really blue. A "blue moon" happens when the full moon occurs twice in a calendar month. There was a full moon on December 2, so the full moon tonight is a "blue moon."

A blue moon is rare, hence the expression "Once in a blue moon," meaning a rare occurrence.

Perhaps because it's so rare, we remember our own lives' blue moons. It's been a long time since I've been there, but I once used to hang out at the Blue Moon Tavern in Seattle's University District. Bet they're rocking tonight.

An astronomical blue moon happens every two and a half years or so - the next one will be in August of 2012 - but having it happen on New Year's Eve is special.

So let's toast the blue moon tonight as we bring in the new year.

1993 Photo by Joe Mabel from Wikimedia Commons.