Nothing in recent memory has enchanted the weather forecasters so much as the blue moon observed over the New Year holiday. None could resist pointing out its rarity by telling us it came only “once in a blue moon.” Okay, so what is a “blue moon”?
It’s a full moon that occurs outside the regular monthly pattern. Most years have one full moon each month, but each solar calendar year has roughly eleven days more than a lunar year, so the extra days accumulate and once every two or three years there’s an extra full moon, which is called a “blue moon.” So actually it’s not all that rare, and it’s probably a mistake to say that something truly unusual—like a friendly post card from the IRS—comes once in a blue moon.
Is it so-called because it looks blue? Maybe, or maybe not. If you had a look at our recent blue moon, it was difficult to see any color in it. The term goes back to the sixteenth century, when church officials, in using a full moon to calculate the date for Easter, noticed that every few years there was an extra full moon, which threw their calculations awry, and so they referred to this moon as a “false moon” or a “betrayer,” using the Old English word belewe, meaning “to betray.” There was a reference to a “belewe moon” in a 1528 pamphlet.
Other stubborn people insist that the phrase refers to an infrequent moon that visibly appears to be bluish in color, a phenomenon that might be caused by dust particles or smoke. After the volcanic eruption of Krakatoa in 1883, the moon looked blue for two years.
Rodgers and Hart’s ballad “Blue Moon” refers to a stroke of romantic luck in which the beloved is seen “standing alone, without a dream in my heart, without a love of my own,” an occurrence that was so rare that it must have happened under a blue moon. (The first lyric was quite different, written for Jean Harlow in a 1933 movie, in which she was saying her prayers and sang, to the same melody, “O, Lord, if you’re not busy up there, I ask for help with a prayer, so please don’t give me the air.” Later, lyricist Lorenz Hart resurrected the tune for another movie, with new lyrics: “Act One, you gulp your coffee and run, into the subway you crowd, don’t breathe—it isn’t allowed.” Hart came up with still another set of lyrics in 1934: “Oh, Lord, I could be good to a lover, but then I always discover the bad in every man.” None of the previous versions having become hits, by 1935 the song was recycled yet again, with the lyrics it now sports, all of which just proves that you should never give up on anything, even the Houston Texans and the Chicago Cubs.)
Once in a blue moon the Bard of Buffalo Bayou tries to spin out some romantic verse, and this is his most recent billet-doux:
I recall an event that was one in a million:
A pale lustrous moon in the somber gray skies,
Then through the mist I saw something vermilion:
The two glowing dots of your little red eyes.