March 31, 1999
Definition of 'Blue Moon' Corrected
Filed at 3:46 p.m. EST
By The Associated Press
BOSTON (AP) -- Once in a blue moon, a widely accepted definition has to be
Take the term ``blue moon'' itself.
For half a century, it's been known as the second full moon in a month, like
the one that appeared Wednesday. But that's wrong, and the editors of Sky &
Telescope say it's their fault: The magazine incorrectly defined the term 53
``I hate to admit it,'' said Roger Sinnott, associate editor of Sky &
Sinnott blamed the goof on an amateur astronomer.
James Hugh Pruett wrote a 1946 piece for the magazine after apparently
misinterpreting a complex 1937 article in the Maine Farmer's Almanac that
essentially, but not clearly, said a blue moon occurs when a season has four
full moons, rather than the usual three. Pruett mistakenly thought that
meant a blue moon is the second full moon within the same month.
Pruett's mistake went unnoticed for decades. A 1980 National Public Radio
story about blue moons used the wrong definition. In 1986, the board game
Trivial Pursuit repeated the error. When two full moons appeared in May
1988, ``radio stations and newspapers everywhere carried an item on this bit
of `old folklore,''' folklorist Philip Hiscock wrote in the magazine's March
Sky & Telescope, based in Cambridge, discovered the error when it was
working on an article about how January and March of this year featured what
would have been two blue moons by Pruett's definition.
Although Sky & Telescope's editors think Pruett's mistake led to the popular
modern mis-definition of ``blue moon,'' it's unclear where the Maine
Farmer's Almanac came up with the rule. The almanac is defunct.
Although the term ``blue moon'' has existed for centuries, Sinnott said his
research of almanacs dating to the early 1800s found no precise definitions
By either definition -- Pruett's or the almanac's -- blue moons occur about
every two or three years, Sinnott said. The last blue moon as defined by the
almanac was in June 1997. The next will be in February 2000.
Although purists may subscribe to the almanac's point of view, Sinnott
thinks Pruett's error will prevail. Pruett died in 1955.
``This meaning is so entrenched now. Nothing we can do is going to put the
genie back in the bottle,'' Sinnott said. ``Our big mistake in 1946 has
really caught on and there's no turning back.''
From: Ron Blue <firstname.lastname@example.org>
To: SETI League <email@example.com>
Date: Wednesday, March 31, 1999 2:05 PM
Subject: SETI Fw: Blue Moon II
>From: Dr. Tony Phillips <firstname.lastname@example.org>
>To: email@example.com <firstname.lastname@example.org>
>Date: Wednesday, March 31, 1999 8:48 AM
>Subject: Blue Moon II
>>Dear Star Trailers,
>>The second blue moon of 1999 takes place later today. To find out how to
>>see it and to learn about the history of the expression "Blue Moon" please
>>visit this URL:
>>Here comes the Blue Moon
>>The article includes pictures of the moon taken by two members of the Star
>>Trails Society. Thanks!
>>Dr. Tony Phillips email@example.com