The most often used definition (and the one I was taught) is a Blue Moon is the second full moon in the same calender month.
Historically, a Blue Moon is the 4th full moon in a season, in which since a "season" is 3 months which normally have 3 full moons in total....but since the lunar cycle is 28 days and the number of days in a month (except a normal Febuary) are over 28 days...we on occasion have a 4th full moon in that quarter or season.
But in modern times, it is safe to say that the second full moon in the same month is the Blue Moon.
I simply thankful that they make the "Full Moon" as a seasonal now.... used to love Abbey Ale...its previous name sake..... named my college dog after it.... it always sucks loving seasonal beers.... love them when you can get them and hate them when you can't.... well you know what I mean.... mmmmm beer
hey!no problem. i like making beer. the seasonals do require more effort - a lot of different ingredients. and the moon family of seasonals do have a variety. the harvest moon makes the brewhouse smell like a pumpkin pie me - i like hops, malt, yeast, and don't forget the water.....
Bluzm2 - if the wheat in bluemoon gets to you, you may want to avoid the rising moon, and honeymoon, as they both contain wheat malt. i do find palemoon good - with the chocolate and dark caramel malt, and HOPS! all in all a nice dark beer, not heavy.