Tag Archives: Idiom

How on Earth did we start using “once in a blue moon”?

You’ve heard it, I’ve heard it, but not many people we know have actually seen a blue moon — so what gives?

Am image of the moon captured through a blue filter.
Image credits steviep187 / Flickr.

“Once in a blue moon” refers to events that only happen very rarely, but it’s a tricky idiom. It doesn’t refer to a moon that’s actually blue, although it can appear to be that color under certain conditions and that probably shaped the saying.

A blue moon is a real occurrence and, you might be surprised to hear, isn’t actually that rare or unpredictable. Blue moons are ‘extra’ full moons of the regular gray color that pop up every two or three years due to misalignment in the lunar and solar circle. But the phrase was first used to refer to something being absurd — like someone arguing that the moon is blue.

So let’s take a look at both halves of this idiom and see why they came to represent the quintessential rare occurrence.

The literal blue moon

Image credits Bobby Jones.

The moon can naturally appear blue or light-blue in the sky. It’s a rare event caused by the presence of dust or smoke particles in the atmosphere at night which alter the way light is diffracted in the atmosphere. If these particles are of the right size, they can scatter the red part of the light spectrum, leaving the rest untouched.

Because visible light spans from red (low-energy) to blue (high-energy), this scattering makes everything take on a blue tint. Since the moon is a white-ish gray on a dark background, this effect causes it to look blue.

This type of blue moon is probably what spawned the idiom. It’s very rare and very unpredictable, as its appearance relies directly on phenomena such as massive wildfires or volcanic eruptions. The fact that it’s entirely dependent on local phenomena also means blue moons are only visible from relatively small areas at a time, not globally — which compounds their rarity.

Some events that led to blue moons include forest fires in Canada, and the eruptions of Mount St. Helens in 1980 and the El Chichón volcano in Mexico in 1983. The eruption of Krakatoa in 1883 (one of the largest in history) reportedly caused blue moons for nearly two years.

A pretty exciting implication of the mechanism that spawns blue moons is a purple sun. In 1950, as huge fires swept the bogs of Alberta, Canada billowing with smoke, leading to sightings of blue moons from the US to England the following night. Two days later, reports of an indigo sun peering through the smoky skies also started to surface.

File:Blood moon 73.jpg
A blood moon.
Image credits Andrey73RUS / Wikimedia.

So why don’t all volcanic eruptions and wildfires turn the moon blue? Well, the size of ash or oil/tar particles they generate is very important. These have to be wider than the wavelength of red light, which is 0.7 micrometers, to block these rays. At the same time, very few to no particles of smaller sizes should be present, as these would help scatter other colors and destroy the overall effect.

Naturally-occurring ash tends to be a mix of particles of various sizes, with most being smaller than the above threshold. Since smaller particles preferentially scatter (i.e. remove) light towards the high end of the spectrum (blue), natural ash clouds typically give everything a shade of red. Red or blood moons are thus a much more common occurrence than blue moons.

The figurative blue moon

Traditionally a blue moon is an additional full moon that appears every 2 and a half years or so, according to NASA. In recent times it has also come to denote the second full moon to appear within a single calendar month in popular use.

This stems from the way lunar and solar cycles relate to one another. There are 29.5 days between full moons, the agency goes on to explain, so each year will have roughly 12.3 full moons. Another implication of this is that 28-days-long February can’t ever have a blue moon.

Both uses of the phrase are considered valid today.

Over time, the idiom turned from meaning that something is impossible to “never” — think along the lines of “I’ll help you when the pigs fly”.

“The definition of a Blue Moon [as] ‘the second full moon in a calendar month,’ is a curious bit of modern folklore. How it emerged is a long story involving old almanacs, a mistake in Sky and Telescope magazine, and the board game Trivial Pursuit,” wrote Dr. Tony Phillips for NASA.

One of the almanacs Dr. Phillips mentions is the Maine Farmer’s Almanac, more specifically its August 1937 issue. The publication followed certain conventions about how to name each moon depending on the time of year. The first full moon of spring for example was called the Egg Moon, Easter Moon, or Paschal Moon, and had to fall within the week before Easter. If a particular season had four moons, the extra one was called a Blue Moon to maintain the naming conventions.

The definition of the blue moon as being the second full month in a single month came, according to Space, from a mistaken interpretation of the term which was popularized by a nationally syndicated radio program in 1980.

Rarer than Blue Moons are double Blue Moons — when the same calendar year gets two of these events. They’re much rarer, only occurring about 3-5 times every hundred years or so; the next double blue moons are expected in 2037. As for a single blue moon, the next one is expected on October 31, 2020.


Where did the “Seven Seas” come from?

What does this idiom mean and who did we inherit it from?


Image via Pixabay.

Some idioms weather the years with grace. Their meaning keeps them relevant even after cultural context leaves them in the dust. We advise our friends against “beating a dead horse”, for example, or point out that you can take it to water but not make it drink — despite the fact that almost nobody today has even interacted with a horse.

Then there are those idioms that aren’t only removed from the modern way of life but are also factually incorrect. Yet they persist. “Sailing the seven seas” is one such idiom. Today, we’ll take a look at how it came to be and which seas, exactly, it harkens to.

Nowadays the term “seven seas” is a shorthand for “all the seas and oceans”; sailing the seven seas, then, means you’re quite the accomplished sailor. But, these “seven seas” carried various meanings throughout history and across cultures. Each civilization understood it differently, through the lens of their religion, culture, and the places they knew. Keep that in mind as we delve into the seven depths of this idiom.

Seven degrees of mystical seas

The earliest use (that we know of) is religious in nature. It comes from the ancient Sumerians, the first people to inhabit Mesopotamia, today’s Iraq. Enheduanna, a high priestess of the goddess Inanna and the moon god Nanna from the city-state of Ur, and the first poet to have their name recorded in history, refers to ‘seven seas’ in a hymn written around 2300 BC. Betty De Shong Meador provides a translation of these hymns in Inanna, Lady of Largest Heart: Poems of the Sumerian High Priestess Enheduanna (University of Texas Press, 2000, page 73), which reads (note that I’ve added all the commas and breaks between verses based on how I interpret the text):

“[….] O, house / Your shining face is the great snake of the reed marsh / Your foundation, o, shrine / The fifty abzu’s, the seven seas, has plumbed the inner-workings of your prince / Decision maker / Crown of wide heaven / He, Ashimbabbar, king of heaven, o , Ur / Shrine has built this house on your radiant and placed his seat upon your dais.”

Ashimbabbar seems to be a normalized, alternative spelling of Nanna’s name; Nanna was a moon god and “the tutelary deity of the city of Ur”, according to Oracc. In this context, abzu’s — from ‘ab’ meaning waters and ‘zu’ meaning deep in Akkadian — are probably fresh underground waters, such as those from springs or dug wells. The Sumerians believed underground waters came from the primordial sea and held an important religious significance.

Ok, hardhats on, it’s time to go on a limb here. In the Babylonian creation epic, Abzu morphs into a key deity. It’s possible they/it has been so all along. But, the fact that Enheduanna cites ‘fifty’ abzu’s suggests to me that this wasn’t the case while she lived, or that the two concepts were similar but already separated. Abzu, as a deity, represents a primordial freshwater ocean which, after coupling with Tiamat, a primordial saltwater ocean, essentially leads to the creation of the Universe. The two birth younger gods, who eventually usurp & murder them and create the world as we know it from their corpses.

Fresh- and salt-water seem to play a central part in the Sumerian religion and culture. The fifty abzu’s (which are fresh, Abzu’s domain) and the seven seas (seas tend to be salty, Tiamat) may have symbolized the primordial, raw stuff of which reality was born from in Enheduanna’s eyes. These ‘seven seas’, then, may have symbolized knowledge, creation, or the essence of both the mundane and the godly — not a stretch of the map. Possibly; that’s my take on it.

Seven western seas

Western cultures likely inherit the idiom from the ancient Greeks and Romans (who basically exported Greek culture throughout Europe). NOAA states that “the Seven [Greek] Seas were the Aegean, Adriatic, Mediterranean, Black, Red, and Caspian seas, with the Persian Gulf thrown in as a ‘sea'”. This fits well with the world as known to the ancient Greeks, who were quite the accomplished sailors themselves. Although they never moved out of the Mediterranean and its connected seas in large numbers, that still places them within a reasonable distance of Mesopotamia, its culture, and our known source for the idiom.

Another reference to the seven seas comes from Pliny the Elder, a Roman writer and admiral. Writing in his book The History of the World (the quote below is taken from Chapter 16, or ‘XVI’ in Roman numerals) these ‘seas’ were, in fact, the navigable salt marshes that the river Po forms when it meets the Adriatic sea.

“And there is not a river againe, that in so little a way, groweth to a greater streame [than the Po]: for over-charged it is and troubled with the quantitie of water, and therefore worketh it selfe a deepe channell, heavie and hurtfull to the earth under it, although it be derived and drawne into the other rivers and goles, betweene Ravenna and Altinum, for 120 miles: yet because he belcheth and casteth them out from him in so great abundance, he is said to make seven seas.”

“[….] All those rivers and trenches afore-said, the Tuscanes began to make first out of Sagis, carrying the forcible streame of the river acrosse into the Atrian meeres, which are called the seven seas, and made the famous haven of Atria a towne of the Tuscanes; of which the Adriaticke sea tooke the name afore time, which now is called Adriaticum.”

Here too we see that the ‘seas’ themselves weren’t necessarily seas per se, but the idiom has at least moved firmly into the realm of geography by this time.

The ‘seas’ in seven seas change over time, keeping pace with the most up-to-date maps. NOAA goes on to explain that in medieval European literature, “the phrase referred to the North Sea, Baltic, Atlantic, Mediterranean, Black, Red, and Arabian seas”. On the Arabian side of the cultural divide, these seven seas were the waters on the Eastern trading routes — the Persian Gulf, the Gulf of Khambhat, the Bay of Bengal, the Strait of Malacca, the Singapore Strait, the Gulf of Thailand, and the South China Sea, according to LiveScience.

As Europe crawled out of the middle ages and reached for cultural dominance through exploration (and sadly, colonization), the seven seas changed to mean the Arctic, the Atlantic, the Indian, the Pacific, the Mediterranean, the Caribbean, and the Gulf of Mexico (when Europeans first reached the Americas), and then the Banda Sea, the Celebes Sea, the Flores Sea, the Java Sea, the South China Sea, the Sulu Sea, and the Timor Sea as trade in spices and tea between Europe and Asia intensified.

In other words, the ‘seven seas’ idiom evolved over time to mean ‘a faraway place’ rather than a particular area or group of seas — probably under the combined efforts of sailors and captains looking to impress land-locked ladies. Maybe it’s an old-timey equivalent to ‘in a galaxy far, far away.’

But this still leaves one part of the puzzle unanswered:

Why is it always ‘seven’?

This is a trickier question to handle.

It may be a vestige of Enheduanna’s hymns. Ancient Sumerians regarded the heavens as being formed of seven domes, each made of a different type of precious stone. It’s possible, then, that each of the seas she refers to could have spawned one of the domes, and the wording just stuck.

Another possible explanation, in my view, has to do with the number itself. One of the most cited papers in psychology today, published in 1956 by George A. Miller, a Harvard psychologist, reports that the average memory span of young human adults is approximately 7 items. Whether this is the cause or not, I cannot say for sure — but the number seven pops up time and time again in all manners of places and contexts.

Rome was built on seven hills, and the world, according to Christian mythos, was made in seven days — although technically the last one was a cheat-day. Christian traditions also tell us of seven deadly sins and seven virtues, of Noah being told to bring seven pairs of every animal aboard his ark, of Jericho’s walls falling on the seventh day after seven priests with seven trumpets march around it seven times. Hinduism tells of seven different chakras, Islam of seven hells and seven heavens, and Mahatma Gandhi lists Seven Blunders of the World — to name a few. A massive poll carried out by writer, mathematician, and broadcaster Alex Bellos a few years ago found that 7 was the most-voted ‘favorite number’ (10% out of some 44,000 voters).

Do I believe that the number 7 is magic? Of course not — the only magic I believe in is Santa Claus and that booze can make me dance. But, seeing the number pop up so often definitely suggests something is special about it.

“Seven is the only number among those we can count on our hands that cannot be divided our multiplied within the group [it’s a prime number]. [It] is the only number between two and ten that is neither a multiple nor a factor of the others. In this way, “lucky number seven” stands alone—and we grasp this implicitly,” Bellos told Brandon Specktor for Reader’s Digest.

“It’s unique, a loner, the outsider. And humans interpret this arithmetical property in cultural ways.”

“By associating seven with a group of things, you kind of make them special too. The point here is that we’re always sensitive to arithmetical patterns, and this influences our behavior—even if we’re not conscious of it.”

One voter from New Zealand even told Bellos in his comments that “People don’t usually tend to pick 7, and I like to be different,” humorously supporting his hypothesis.