Posted on 12/31/2009 11:29:02 AM PST by Star Traveler
The trendy definition of "blue Moon" as the second full Moon in a month is a mistake.
by Roger W. Sinnott, Donald W. Olson, and Richard Tresch Fienberg
A rising full Moon lights the scene in The Fishing Party, painted by Fitz Hugh Lane after a visit to the coast of Maine in August 1850. That month contained a Fruit Moon, according to the Maine almanac's rules.
Recent decades have seen widespread popular embrace of the idea that when a calendar month contains two full Moons, the second one is called a "Blue Moon." The unusual pattern of lunar phases in early 1999 — two full Moons each in January and March, and none at all in February — triggered a groundswell of public interest. Countless newspapers and radio and TV stations ran stories about Blue Moons.
In an article "Once in a Blue Moon", folklorist Philip Hiscock traced the calendrical meaning of the term "Blue Moon" to the Maine Farmers' Almanac for 1937. But a page from that almanac belies the second-full-Moon-in-a-month interpretation.
With help from Margaret Vaverek (Southwest Texas State University) and several other librarians, we have now obtained more than 40 editions of the Maine Farmers' Almanac from the period 1819 to 1962. These refer to more than a dozen Blue Moons, and not one of them is the second full Moon in a month. What's going on here?
Blue Moons and the Seasons
Several clues point to a strong connection between the almanac's Blue Moons and the four seasons of the year. All of the listed Blue Moons fall on the 20th, 21st, 22nd, or 23rd day of November, May, February, or August. These dates fall about a month before the Northern Hemisphere winter and summer solstices, and spring and fall equinoxes, respectively, which occur on similar day numbers.
Although the idea of a seasonal pattern suggested itself to us immediately, verifying the details required a lot of detective work. We found that the Blue-Moon definition employed in the Maine Farmers' Almanac is indeed based on the seasons, but with some subtle twists.
Instead of the calendar year running from January 1st through December 31st, the almanac relies on the tropical year, defined as extending from one winter solstice ("Yule") to the next. Most tropical years contain 12 full Moons — three each in winter, spring, summer, and fall — and each is named for an activity appropriate to the time of year (such as the Harvest Moon in autumn). But occasionally a tropical year contains 13 full Moons, such that one season has four rather than the usual three.
Today we usually mark the beginning of the seasons when the Sun's celestial longitude passes 0° (spring), 90° (summer), 180° (autumn), and 270° (winter). The Sun appears to move along the ecliptic at a variable rate because of the Earth's not-quite-circular orbit, so the seasons defined this way are not equal in duration. Another approach uses the dynamical mean Sun or fictitious mean Sun — imaginary bodies that move along the ecliptic and the celestial equator, respectively, at a constant rate and produces seasons of equal length. The Maine almanac defines the seasons using this alternative method.
The almanac also follows certain rules laid down as part of the Gregorian calendar reform in 1582. The ecclesiastical vernal (spring) equinox always falls on March 21st, regardless of the position of the Sun. Lent begins on Ash Wednesday, 46 days before Easter, and must contain the Lenten Moon, considered to be the last full Moon of winter. The first full Moon of spring is called the Egg Moon (or Easter Moon, or Paschal Moon) and must fall within the week before Easter.
At last we have the "Maine rule" for Blue Moons: Seasonal Moon names are assigned near the spring equinox in accordance with the ecclesiastical rules for determining the dates of Easter and Lent. The beginnings of summer, fall, and winter are determined by the dynamical mean Sun. When a season contains four full Moons, the third is called a Blue Moon.
Why is the third full Moon identified as the extra one in a season with four? Because only then will the names of the other full Moons, such as the Moon Before Yule and the Moon After Yule, fall at the proper times relative to the solstices and equinoxes.
Questions and Answers
During the period 1932 to 1957, under the editorship of Henry Porter Trefethen (1887-1957), the Maine Farmers' Almanac consistently listed Blue Moons derived from the convoluted seasonal rule just described. So where did the modern convention — that a Blue Moon is the second full Moon in a calendar month — come from? Sky & Telescope has, and is, the answer!
Laurence J. Lafleur (1907-66) of Antioch College, Ohio, discussed Blue Moons in a question-and-answer column in Sky & Telescope, July 1943, page 17, citing the 1937 Maine Farmers' Almanac as his source. It is clear that Lafleur had a copy of the almanac at his side as he wrote, since he quoted word for word the commentary on the August 1937 calendar page. This commentary notes that the Moon occasionally "comes full thirteen times in a year," but Lafleur did not judge whether this referred to a tropical year or a calendar year. More important, he did not mention the specific dates of any Blue Moons and never said anything about two full Moons in one calendar month.
Oops!
Some three years later, in March 1946, an article entitled "Once in a Blue Moon" appeared in Sky & Telescope (page 3). Its author, James Hugh Pruett (1886-1955), was an amateur astronomer living in Eugene, Oregon, and a frequent contributor to S&T. Pruett wrote on a variety of topics, especially fireball meteors. In his article on Blue Moons, he mentioned the 1937 Maine almanac and repeated some of Lafleur's earlier comments. Then, unfortunately, he went on to say, "Seven times in 19 years there were — and still are — 13 full moons in a year. This gives 11 months with one full moon each and one with two. This second in a month, so I interpret it, was called Blue Moon."
Pruett must not have had the 1937 almanac handy, or he would have noticed that the Blue Moon fell on August 21st (obviously not the second full Moon that month) and that 1937 had only 12 full Moons. But only in retrospect is his error so obvious.
Modern Folklore
Sky & Telescope adopted Pruett's new definition, using it in a note entitled "'Blue' Moons in May" on page 176 of the May 1950 issue. In a bizarre twist, the data on lunar phases for this note came from none other than H. Porter Trefethen of Winthrop, Maine, editor of the very almanac Pruett misread four years earlier! But Trefethen himself never called the second full Moon in a month a Blue Moon. The "'Blue' Moons" headline was likely added by Sky & Telescope's founding editor, Charles A. Federer Jr. Federer agreed that he probably wrote that headline with Pruett's then-recent article in mind and without consulting Trefethen.
As Hiscock explained in the March issue, widespread adoption of the second-full-Moon-in-a-month definition followed its use on the popular radio program StarDate on January 31, 1980. We examined this show's script, authored by Deborah Byrd, and found that it contains a footnote not read on the air that cites Pruett's 1946 article as the source for the information. Byrd now writes for the radio program Earth & Sky, whose Web site contains a note giving her perspective on this modern contribution to lunar folklore.
With two decades of popular usage behind it, the second-full-Moon-in-a-month (mis)interpretation is like a genie that can't be forced back into its bottle. But that's not necessarily a bad thing. Rather than argue over whether to celebrate the dawn of the new millennium on January 1st in 2000 or 2001, those with the sunniest outlooks will celebrate twice. Why not treat Blue Moons the same way, marking both the second full Moon in a calendar month and the third full Moon in a season with four? "Even if the calendrical meaning is new," said Federer, "I don't see any harm in it. It's something fun to talk about, and it helps attract people to astronomy."
That's the problem with being "indoctrinated" by the MSM... :-)
By Jay Michaels
Story Published: Dec 30, 2009 at 8:38 PM CST
When somebody says that something happens 'every once in a blue moon,' usually they mean it doesn't happen very often.
A local astronomer says that back in the 1940's, a researcher for 'Sky and Telescope Magazine' managed to misquote the definition of a blue moon as being a second full moon during a calendar month.
He says the Maine Farmer's Almanac defined the third full moon during a season – as a blue moon.
Faulkner Planetarium Manager Rick Greenawald says, “If there were four full moons during one of those seasons, the third full moon was referred to as the blue moon to keep the other moons in line with their traditional interpretation, harvest, hunters, and so forth.”
He says in seven out of 19 years, a total of 13 full moons will occur in a twelve month period; and he says by using the original method blue moons happen more often than the 'two full moons in a calendar month' reckoning.
And because of this historical and long-standing definition (prior to the mistaken article which ended up changing a lot of people's minds to the wrong definition) -- the Blue Moon does not occur until the moon of November 6 to December 4th of 2010.
For the year 2010, these are the dates of the moons in the northern hemisphere using UTC calculations. These dates use the actual solstices and not the artificial solstices that give each season an equal number of days.
A blue moon is a full moon that is not timed to the regular monthly pattern. Most years have twelve full moons which occur approximately monthly, but in addition to those twelve full lunar cycles, each solar calendar year contains an excess of roughly eleven days compared to the lunar year. The extra days accumulate, so that every two or three years (on average about every 2.7154 years[1]), there is an extra full moon. The extra moon is called a "blue moon." Different definitions place the "extra" moon at different times.
Then there are The Marcells. Great song!
The way I read the article, the blue moon occurred on Dec. 2.
So is there going to be a full moon in February of this year?
That’s 2010 not 2009... :-)
For the year 2010, these are the dates of the moons in the northern hemisphere using UTC calculations. These dates use the actual solstices and not the artificial solstices that give each season an equal number of days.
The first crossover recording to rock and roll came from Elvis Presley, but the version that really stirred things up came from The Marcels, a doo-wop group. In 1961 the Marcels had 3 songs to record and needed one more. Producer Stu Phillips did not like any of the other songs except one that had the same changes as Heart and Soul and Blue Moon. He asked them if they knew either, and one knew Blue Moon and taught it to the others, though with the bridge or release (middle section - "I heard somebody whisper...") wrong. The famous introduction to the song ("bomp-baba-bomp" and "dip-da-dip") was an excerpt of an original song that the group had in its act. The record reached #1 on the Billboard Pop chart for three weeks and #1 on the R&B charts. [3] The Marcels version of "Blue Moon" sold a million copies, and is featured in The Rock and Roll Hall of Fame's 500 Songs that Shaped Rock and Roll.
Is that because that in 2009 the full moon on Dec. 2 was in Autumn and the one tonight is in Winter?
Written by Fraser Cain
Here is the schedule for all the Full Moons that will happen in 2010. If you're going to go skywatching, remember that the best time to see the night sky is when you have a new moon. When there's a full moon, the dimmer skies are washed out. Please note that all the times listed are in Universal Time.
Full Moon for January, 2010
January 30, 06:18Full Moon for February, 2010
February 28, 16:38Full Moon for March, 2010
March 30, 02:25Full Moon for April, 2010
April 28, 12:18Full Moon for May, 2010
May 27, 23:07Full Moon for June, 2010
June 26, 11:30Full Moon for July, 2010
July 26, 01:37Full Moon for August, 2010
August 24, 17:05Full Moon for September, 2010
September 23, 09:17Full Moon for October, 2010
October 23, 01:36Full Moon for November, 2010
November 21, 17:27Full Moon for December, 2010
December 21, 08:13
A little note here is that I don't see the location for the times, so I'm assuming it's UTC.
Is that because that in 2009 the full moon on Dec. 2 was in Autumn and the one tonight is in Winter?
The Farmer's Almanac did say that they went by the Seasons (Winter, Spring, Summer, and Fall) -- so that would make sense.
I’m devastated. First, Walter Williams tells me today does not end the decade and now the second full moon of the month is not ‘blue.’ I feel as if my IQ has been lowered 50%.
Wow! Great article! It was an eye-opener. For all my life, I’ve been under the false impression of the “2 new-moons in a month” definition of a blue moon. Now, I now the truth: The third full-moon in a season of four full-moons is a true blue moon!
I’m quite pleased that Sky & Telescope has fessed up to their own errors from 1943 and 1946 which seems to be the cause of the blue-moon confusion.
Thanks for posting it.
Cheers
P.S. - Now I can blow away my buddies with this little tidbit: February CAN have a blue-moon!
Cheers
January: Old Moon, or Moon After Yule
February: Snow Moon, Hunger Moon, or Wolf Moon
March: Sap Moon, Crow Moon or Lenten Moon
April: Grass Moon, or Egg Moon
May: Planting Moon, or Milk Moon
June: Rose Moon, Flower Moon, or Strawberry Moon
July: Thunder Moon, or Hay Moon
August: Green Corn Moon, or Grain Moon
September: Fruit Moon, or Harvest Moon
October: Harvest Moon, or Hunter’s Moon
November: Hunter’s Moon, Frosty Moon, or Beaver Moon
December: Moon Before Yule, or Long Night Moon
Source:
Guy Ottewell’s Astronomical Calendar
One of the best astronomical calendars in existence!
Well, I would say — on the other hand — that you’re smarter now, since you have the correct information and know why it’s correct and what caused everyone else to have the wrong information... :-)
I went around and around with some people back in 1999 about the Blue Moon, too... :-)
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