Once in a Blue Moon
Houston County Courier - January 2010
CROCKETT – Anyone outdoors on the evening of Thursday, Dec. 31 may have had the opportunity to see the rare occurrence of a “Blue Moon” in the skies over Houston County.
The term "Blue Moon" simply refers to the second full moon in a calendar month, something that hasn't happened on a New Year's Eve for nearly 20 years, NASA reported. A blue moon on Dec. 31 is rare.
December 1990 ended with a blue moon.
Most months have just one full moon, because the 29.5-day cycle of the moon matches up pretty well with the length of calendar months.
Occasionally, there will be two full moons in a month, something that happens about every 2.5 years, officials at NASA reportedly said.
The Farmers' Almanac lists these Algonquin Indian names for the full moon of each month:January: Wolf Moon; February: Snow Moon; March: Worm Moon; April: Pink Moon; May: Flower Moon; June: Strawberry Moon; July: Buck Moon; August: Sturgeon Moon; September: Corn Moon; October: Harvest Moon; November: Beaver Moon; and December: Cold Moon.
Elvis Presley crooned about it when he sang the old Rodgers and Hart song "Blue Moon," in which he stood alone without a dream in his heart or a love of his own.
He struck a more hopeful tone in another tune, singing about his love returning to his arms "When My Blue Moon Turns to Gold Again." He also covered Bill Monroe's bluegrass classic, "Blue Moon of Kentucky."
The term "Blue Moon" is commonly used metaphorically to describe the rarity of an event, as in the idiomatic expression, "once in a blue moon."
The most literal meaning of blue moon is when the moon, not necessarily a full moon, appears to a casual observer to be unusually bluish, which is a rare event.
According to Wikipedia, the effect can be caused by smoke or dust particles in the atmosphere, as has happened after forest fires in Sweden and Canada in 1950 and, notably, after the eruption of Krakatoa in 1883, which caused the moon to appear blue for nearly two years.
The particles in the atmosphere have to be about one micrometre in diameter; under these circumstances, long-wavelength light, which appears red to a viewer, is scattered out of the line of sight and short-wavelength light, which appears blue to a viewer, is selectively transmitted into a viewer's
Historically, moons were given folk names, 12 each year, to help people to prepare for different times of the year and the related weather and crop needs.
Names varied with locality and culture, often with descriptive names such as harvest moon, growing moon, snow moon, and egg moon.
Most years have 12 moons but in the years with 13 full moons the monthly "seasons" would be expected to come too early, for example, hens would not recommence laying their eggs by the fourth full moon since it was still too cold, so the early moon was named a "blue moon.”
This then re-aligned the rest of the year's moons and "seasons.”
The origin of the term "blue moon" is steeped in folklore, and its meaning has changed and acquired new nuances over time.
Some folktales say that when there is a full blue moon, the moon had a face and talked to those in its light.
According to Rainer Werner Fassbinder, "Every seventh year is one of the moon. In such years people suffer increasingly from emotional ups and downs and depression. Moon years such as 1978 are years that have 13 new moons. This inevitably leads to personal catastrophes."
In the 19th and early 20th centuries, the Maine Farmers' Almanac listed blue moon dates for farmers. These correspond to the third full moon in a quarter of the year when there were four full moons, normally a quarter year has three full moons.
Names are given to each moon in a season: For example, the first moon of summer is called the early summer moon, the second is called the midsummer moon, and the last is called the late summer moon.
When a season has four moons the third is called the blue moon so that the last can continue to be called the late moon.
The division of the year into quarters starts with the nominal vernal equinox on or around March 21.
This is close to the astronomical season but follows the Christian computus used for calculations of Easter, which places each equinox evenly between the summer and winter solstices to calculate seasons rather than using the actual equinox.
Some naming conventions keep the moon's seasonal name for its entire cycle, from its appearance as a new moon through the full moon to the next new moon.
In this convention a blue moon starts with a new moon and continues until the next new moon starts the late season moon.
Wikipedia has a formula online to calculate the moon names for the seasons using the appearance of the new moon.
According to Wikipedia, the following blue moons will occur between 2009 and 2015. These dates use UTC as the timezone; months will vary with different timezones.
Using the Farmers' Almanac definition of blue moon (meaning the third full moon in a season of four full moons), blue moons occur: Nov. 21, 2010, and Aug. 21, 2013.
Two full moons in one month in 2009 on Dec. 2, and Dec. 31, Blue Moon on New Year's Eve, in 2012 on Aug. 2, and Aug. 31 and in 2015 on July 2, and July 31.
Note that, unlike the astronomical seasonal definition, these dates are dependent on the Roman calendar and time zones. E.g. the full moon at 2009-12-31 19:13 UTC occurs early the next day in eastern countries (Australia and most of Asia), where the calendar blue moon will not occur until late January 2010.