Thursday, May 31, 2007
"Once in a Blue Moon" Tonight
Not really. But it will be the second full moon of May and, according to folklore, that makes it a rare Blue Moon.
If you told a person in Shakespeare's day that something happens "once in a Blue Moon" they would attach no astronomical meaning to the statement. Blue moon simply meant rare or absurd, like making a romantic date for "the Twelfth of Never."
But "meaning is a slippery substance," writes Philip Hiscock of the Dept. of Folklore, Memorial University of Newfoundland. "The phrase 'Blue Moon' has been around a long time, well over 400 years, and during that time its meaning has shifted.
"The modern definition sprang up in the 1940s. In those days the Maine Farmer's Almanac offered a definition of Blue Moon so convoluted even professional astronomers struggled to understand it. It involved factors such as ecclesiastical dates of Easter and Lent, tropical years, and the timing of seasons according to the dynamical mean sun.
Aiming to explain blue moons to the layman, Sky & Telescope published an article in 1946 entitled "Once in a Blue Moon." The author James Hugh Pruett (1886-1955) cited the 1937 Maine almanac and opined that the "second [full moon] in a month, so I interpret it, is called Blue Moon. "This was not correct, but at least it could be understood. And thus the modern Blue Moon was born.
Surveying the last four centuries of literature and folklore, "I have counted six different meanings which have been carried by the term," recounts Hiscock. In song [video], for instance, Blue Moons are a symbol of loneliness; when love conquers all, the Blue Moon turns gold. "This makes discussion of the term a little complicated," he says.