[1raider1]

I’m confused. If we have 13 full moons in 2009 isn’t one of them a blue moon? According to the Farmer’s Almanac you have to have four full moons in any one season. This year we had 13 full moons, but only three per season. Am I missing something?

[Northern Yankee]

Yeah... I'm at a loss to figure this thing out as well.

Let's just call the damned thing a blue moon, have a few drinks, kiss our loved ones and call it a night!

Happy New Year, Mate!

[Political Junkie Too]

This year we had 13 full moons, but only three per season. Am I missing something?

Yes. The seasons are defined as the times between the solstices and equinoxes. These are not absolutely defined dates astronomically, but the civil calendars fix them to be around the 21st of March, June, September, and December. However, astronomically, the dates shift due to the earth's elliptical orbit and wobble due to precession.

Thefore, the "13th full moon" in a year may not be the fourth full moon in a season.

-PJ