Blogger’s Note: Apologies if you received notification that this post was published last Thursday, and were then unable to open it. I had an issue last week with the post not displaying in paragraphs, and I was trying to troubleshoot it when I accidentally published this post in draft form.

Blogger’s Second Note: According to my Excel tracking sheet, this is the 200th post that I have published, since I started the blog in November 2019. This means that, at an average of 1500 words a post, for the same investment of effort I could have written a 300,000-word novel and made my fortune. And there’s my life in a nutshell, really.

Let me start by wishing you all a happy and healthy 5784. In this post, in a rather roundabout way, I celebrate the everyday miracle that is the passage of the year.

From the mid-1960s until, in its second resurrection, a one-off special in 2011, BBC television featured, on and off, a celebrity panel game show entitled Call My Bluff. Two teams of three competed to earn points by identifying the correct definitions of obscure words. The teams took turns to give three definitions, one true and two bluffs. If the opposing team correctly identified the true definition, they earned a point; if not, the bluffing team earned a point.

Examples of words used in the show include queach, strongle, ablewhacket, hickboo, jargoon, zurf, morepork, and jirble (which clearly indicates that the show was designed to be a place where people who loved words could meet to share their enjoyment of the idiosyncrasies of the English language). The show also had an inbuilt upper-class pomposity, the original teams being led by Robert Morley (noted for his numerous film portrayals of archetypal pompous upper-class establishment characters) and Frank Muir. The latter was a wordsmith best known for his partnership with Denis Nordern, writing comedy for radio – Take It From Here, Whacko, Brothers in Law (no hyphens, since it was a sit com about a law firm). However, he was also characterised by his upper-class accent (particularly his slightly weak, unrolled ‘r’ sound) and his pink, spotted bow tie. Later team leaders included a genuine lord (Patrick Campbell, 3rd Baron Glenavy) and the very upper-crust actress Joanna Lumley.

You will doubtless not be too shocked to discover that I, or rather my even more pretentious late-teen to early-adult self, loved the game.

I mention it only as an introduction to the Call-My-Bluff-type challenge I set you today. I am going to offer you no fewer than four explanations of the origin of a well-known phrase or saying, and ask you to guess which, if any, is the correct one. (I am already picking out in my mind a select group of potential readers who will actually know the correct answer.) Full disclosure: until a couple of weeks ago I laboured under the delusion that one of the bluffs was, in fact, the correct explanation. Further full disclosure: Just because an explanation is not the correct basis for the phrase ‘once in a blue moon’ does not necessarily mean that the facts stated in the explanation are false.

A couple of weeks ago, on 31 August, we had the rare occurrence of a super blue moon. You can see it here, as it appeared over Darwin. The ‘super’ refers to the fact that it was a full moon occurring at the point in the moon’s orbit around the earth when it is closest to the earth, resulting in the moon appearing to us as larger than it does at any other time. The ‘blue’ refers to…what, exactly? We assume that it is something rare, because it has given rise to the phrase ‘once in a blue moon’. However, it is far from clear exactly what that rare occurrence is. So, which of the four explanations below do you buy?

Just before we dive into the explanations, some background in simple astronomical arithmetic is probably a good idea. About halfway through the next six paragraphs, you may, however, start to disagree that it is a good idea. It’s not in the test, so feel free to skip it.

We need to understand the relation between the lunar and the solar cycle. The Gregorian calendar is a solar calendar, whose two basic units are the day (the length of time it takes the earth to spin on its axis one complete revolution) and the year (the length of time it takes the earth to orbit the sun once).

• A solar (or tropical) year is approximately 365.24 days long (which explains why we add a leap day every four years – and why we also don’t add a leap day when the year is divisible by 100 but not divisible by 400, because 0.24 is just a bit less than a quarter).
• A lunation (one lunar cycle – a lunar ‘month’, if you will) is 29.53 days.

This means that, if we want to have a calendar based on lunar months, but also want it to align with the solar calendar, we have a problem, because 365.24 divided by 29.53 is 12.37.

In other words, if we had 12 lunar months in a year, the year would be about 11 days shorter than the solar year. If we had 13 lunar months, it would be about 19 days longer than the solar year.

For this reason, several civilisations developed a calendar based on a cycle of 19 years (known as a Metonic cycle, after the Greek astronomer Meton who ‘discovered’ it). 11 days is about 7/19 of a solar month. So, if we add a lunar month 7 times in every cycle of 19 years, then every 19 years our calendar will realign with the solar calendar.

This is how the Jewish calendar works (by adding – or intercalating – an extra month every two or three years during the 19-year cycle). It is also the way the Babylonians, the early Romans, the Bahais, and probably the Iron Age Celts and Polynesians, among others, constructed their calendars, some of them at least 1500 years before Meton.

And so to the explanations of the origin of the phrase ‘once in a blue moon’:

Explanation A

Explanation B

The term ‘blue moon’ originated in an anti-clerical pamphlet (attacking the Roman clergy, and Cardinal Thomas Wolsey in particular) by two converted Greenwich friars, William Roy and Jerome Barlow, published in 1528 under the title Rede me and be not wrothe, for I say no thynge but trothe (Read Me and Don’t Get Angry for I Say Nothing but the Truth), . The relevant passage reads:

O churche men are wyly foxes […] Yf they say the mone is blewe / We must beleve that it is true / Admittynge their interpretacion.] (O, churchmen are wily foxes…If they say the moon is blue, we must believe that it is true, accepting their interpretation.)

The context of the passage is a dialogue between two priest’s servants, spoken by the character “Jeffrey” . The intention may simply be that Jeffrey makes an absurd statement, “The moon is blue”, to make the point that priests require laymen to believe in statements even if they are patently false.

From here, it is a short step to saying that something happens only when the moon is blue: in other words, never.

Explanation C

Because there are 12 solar months in a year and, in some years, 13 lunar months, there are occasions when two full moons occur in the same solar month. (This cannot happen in February, because even in a leap year February has too few days to fit in two full moons). For example, in 2023, there was a full moon on 1 August and again on 31 August. When this happens, printed calendars traditionally print the second full moon in blue; hence it is known as a blue moon.

Explanation D

The phrase ‘blue moon’ derives from ‘belewe’, which is an Old English word meaning ‘betray’, because the extra full moon betrays the usual perception of one full moon per solar month.

Now we come to what I believe is known in the trade as ‘the big reveal’. The answer is that, in fact, none of the answers is correct. If you feel cheated, I would point out that, in the fourth paragraph of this post I invited you: “to guess which, if any, is the correct one.”

I always believed it was Explanation C, but, in fact, this is based on an incomplete piece of research by a writer on astronomy. Which leads us to Explanation E, the genuine explanation.

Explanation E

The Maine Farmers Almanac, in the 19th and early 20th centuries, divided the year into four ‘average’ seasons, each three solar months long. Normally, a season would include 3 full moons. Each of these full moons had a specific name, as follows:

• 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: Full Corn Moon
• October: Hunter’s Moon
• November: Beaver Moon
• December: Cold Moon

As you can see, these names very much reflect the agricultural and natural world of North America.

In a season that included a fourth full moon, the third full moon of the season was designated a Blue Moon, and the first, second and fourth full moons of the season used the normal full moon names. In other words, a blue moon is not necessarily the second full moon in a month (although it often happens to be that as well); it is, rather, the third full moon of a season with four full moons..

Which is probably more than you wanted or needed to know on the subject, but I hope at least some of you enjoyed Explanations A and B, which are factually correct, but do not account for the use of ‘blue moon’ in the phrase ‘once in a blue moon’, and Explanation D, which is spurious speculation.

Fortunately, I can usually bank on getting at least one picture of each grandson having a good time far more frequently than once in a blue moon!