Full Moon over Fairfield Glade, Tennessee. November 21, 2010.
Sunday evening’s full moon is the first in November, so most people would say that it is not a blue moon. A full moon is considered to be a blue moon when it is the second full moon of the month.
BUT . . . This definition of a blue moon came about in 1943 in an article written for Sky & Telescope magazine. Prior to that, according to an article written in 1937 for Maine Farmers’ Almanac, a blue moon was the third of four full moons in a season.
Names were assigned to each moon in a season: For example, the first moon of summer was called the early summer moon, the second was the midsummer moon, and the last was called the late summer moon.
Seven times in 19 years there are 13 full moons in a calendar year, which means that one season that year has four full moons. When a particular season has four full moons, the third was called a blue moon so that the fourth and final one could continue to be called the late moon.
The full moon on November 21 was the third of the autumn season this year — the first two were September 23 and October 22. The fourth full moon of autumn in 2010 will occur 2:13 a.m. CST on December 21, 15 hours and 25 minutes before the solstice and the arrival of winter in the Northern Hemisphere. So according to the Maine Almanac rule, the third full moon of the 2010 fall season on November 21 was a blue moon.
I don’t know if this should be called a blue moon or not. All I know is that it was beautiful.
Senior Moments 