What is a Blue Moon?
What is a Blue Moon?
In 1999, there were two blue moons very close together. One on January 31st (after the full moon on Jan. 2nd) and the other on March 31st (after the full moon on March 2nd).
There was another in November 2001, but not again until July 2004.
There was a blue moon in May 2007 (and one in June 2007 for those in Europe and Asia), and the next ones will be December 2009, August 2012, then July 2015.
And we won't see two blue moons in one year again until 2018!
Sorry, it's not really blue : (
The first definition (second full moon in a calender month) was invented by Sky and Telescope magazine in March 1946, apparently by a contributor who misinterpreted the Maine Farmer's Almanac. This definition was subsequently promulgated in other news media, and has become almost the "accepted" one, despite its modernity. In March 1999, Sky and Telescope magazine finally published a very belated correction/retraction.
The second definition (fourth full moon in a season) is closer to the mark, but alas is not quite right either. A traditional blue moon does occur only when there are four full moons in a season, but it is the _third_ of these which is the blue moon, not the fourth. Traditionally, names are given to the first, second, and last full moon of a season, so it is the third moon of a season with four which is "blue". This is the traditional definition, but its origins are a bit hazy."
Check the Old Farmer's Almanac at
http://www.farmersalmanac.com/astronomy/fullmoonnames.html
which gives the North American names for the full moons, and explains the Blue Moon naming confusion.
Here are some pictures of the January and March 1999 blue moons, and also the one in May, 2007:
6:00 pm, rising behind the treetops.
9:30 pm
A hazy evening in Northern Arizona
