Blue Moon

OK, a little relearning. A "Blue Moon" is not the second full moon that occurs within a calendar month. That definition came from an error printed in the Sky & Telescope magazine back in the '40's. (Not enough nerds around yet to challenge the error?)There are normally 12 full moons in a tropical year (defined as winter solstice to winter solstice). Each of the 4 seasons has 3 full moons. Since a year is a little longer than 12 lunar months, every 2 or 3 years there is a season with 4 full moons. Each full moon has a name (Harvest Moon, Hunter's Moon, Egg Moon, etc.) in accordance to when it occurs (full moon nearest the autumnal equinox, first full moon after the Harvest moon, full moon occurring the week before Easter, etc.). What do you call the extra full moon when it occurs? So, "Blue Moon" became the name given to the 3rd full moon in a season w/ 4 full moons. This is a picture from November 21st - the only Blue Moon in 2010.