By Mike Cronin
Thursday, December 31, 2009
Last updated: 10:39 am
Tonight's blue moon might not be the auspicious start to a new decade that people hope it is.
The month's second full moon could be the devil taunting humanity -- at least that's what Christians believed during the Middle Ages, said Gregory McNamee, who writes for Encyclopedia Britannica.
Medieval Christians used the moon to identify the correct date for Easter, said McNamee, who's based in Tucson.
Each month was supposed to have just one full moon, so the Christians called a second one "belew" -- Middle English for "false" or "betrayer," McNamee said.
"It was like Satan was trying to trick you so you can't celebrate the real date of Christ's Resurrection," he said.
So The Lord of the Bottomless Pit has something in common with the song that begins "Bom-ma-bom, a-bom-bom-a-bom." The Marcels' "Blue Moon" hit No. 1 in 1961.
The moon becomes full a second time this month at 12:13 p.m., Pittsburgh time, today, said Kim Long, author of "The Moon Book" and "The Moon Calendar."
A blue moon last occurred on New Year's Eve in 1990, said Alan MacRobert, a senior editor at Sky & Telescope Magazine in Cambridge, Mass.
Despite the phrase, "once in a blue moon," blue moons are fairly common.
They appear about once every 2.7 years, MacRobert said. The last blue moon filled the sky in May 2007. The next one is in August 2012.
"And they have no importance whatsoever," he said. "It's just a cool, interesting fluke of the calendar -- not an indication of how the universe works."
The concept, however, of a blue moon meaning something that happens never or very rarely dates to 16th century England, said Long, who's based in Denver.
"Yet several times since then, the moon has looked blue due to ash, dust particles or pollutants in the atmosphere," Long said.
McNamee conceded that popular musicians such as Bill Monroe, who penned and sang "Blue Moon of Kentucky" in 1946, and Lorenz Hart and Richard Rodgers, who recorded "Blue Moon" in 1933, were not even remotely aware of the devil's possible influence on blue or "betrayer" moons.
"They're using 'blue' to mean 'down' or 'sad,'" McNamee said.
"Still, it is interesting that no positive songs to my knowledge exist about blue moons -- only sad and lonesome ones."
On average, blue moons occur:
• Once every 2.7 years
• Seven times every 19 years
• Once every 33 months
• Thirty-seven times every century
• Once every 33 full moons