So What is a Blue Moon Anyway and is it Really Blue?


mapWhere did the Phrase Blue Moon Come From?

In preparing for the Blue Moon Bash at The Black Bear Bistro on July 30 2015 from 5-7 I decided I should do some homework and look into what exactly is a Blue Moon and where did the phrase come from.  There sure is plenty of info from the seasonal definition or a calendar definition, a slap at religious clergy — even a fancy cocktail.  I encourage you to do your own research if you are so inclined.

Two Definitions

The Traditional definition (aka seasonal) and the one most people follow is by Maine’s Farmer’s Almanac which is defined as a 3rd Full Moon in a season that has 4 full moons.  A more modern definition (aka calendar) is an extra full moon during a calendar month.  The traditional definition goes back to very early times.

The occurrence of a Full Moon once was used to determine the date of Easter.  Clergy would identify the Lenten Moon.  When a moon arrived too early (meaning the populace would need to fast an additional month) the Clergy named the moon “belewe” meaning Betrayer. Interesting to note that the first known recorded use of the phrase “Once in a blue Moon” was in an anti-clerical pamphlet published in 1528 by William Roy and Jeremy Barlowe questioning whether people should believe everything the clergy had to say. Referring to the betrayer definition and the Clergy’s random use of power and facts mixed with fiction.  It was also at this time the idea that the moon was made of cheese arose – also a slight on the Clergy.

In Folklore a name was given to each of the 12 full moons.  When the occasional 13th moon arrived early it was called a blue moon. Due to the rarity of its occurrence the phrase once in a blue moon was coined as a rare event.

When you do the Math you begin to understand why Blue Moons are considered rare.  There 365.24 days per calendar year.  A lunar cycle is 29/53 days equating to 12.37 lunation cycles.  The extra days accumulate resulting a 13th Full moon every 2-3 years.

Fact or Fiction:  Is the extra moon named for its color?  Fiction.  A Moon showing signs of the color blue come from a disturbance in the earth’s atmosphere most often fire.  In 1883 after the eruption of Krakatoa the moon appeared blue for 2 years.  A notation in Explorer Robert Falcon Scott’s journal on July 11, 1891 in the Antarctic read “air thick with snow and the moon a vague blue.  In 1950 and 1951 after intense forest fires in Sweden and Canada the Moon appeared blue.

Believe it or not, there are 6 definitions or uses of the term blue moon

  1. A Rare Event
  2. Never
  3. Absurd
  4. Historical times when Moon was blue due to atmospheric conditions
  5. Sad and lonely
  6. A Cocktail

Next seasonal Blue Moons: May 21, 2016, May 18, 2019, August 22, 2021

Next Calendar Blue Moons; Jan 2 & 31, 2018 and Mar 2, 30, 2018

Next New Year’s Eve with Blue Moon (and lunar eclipse) 2028