So there have been thirteen full moons in 2020, with the last one appearing tonight, December 29th, and in most years that would be a minor note of interest, but the fact that it’s 2020 casts a pallor over everything. It’s been the year of no cheer, three-hundred and sixty-six days in a haze, eight thousand eighty four hours of glower, twelve months of stormy fronths. And of all the numbers thirteen is considered the unluckiest. It’s the only number with its own phobia, triskaidekaphobia, which has its first recorded use, according to the OED, in 1911, which is ironic because if you add up the numbers in that year they only add up to twelve. There are hotels that skip the thirteenth floor and manufacturers who try to avoid putting the number 13 on their products. In Tarot decks the Death card is number 13 of the Major Arcana, and let’s not forget the Friday The 13th Movies that got increasingly terrible as they went on and it’s ironic that there are only twelve. At the Last Supper there was Jesus and the twelve apostles, which may be the origin of a belief that it’s unlucky to have thirteen dinner guests. Twelve is considered luckier, at least at the end of the year—traditionally there are twelve days of Christmas which used to mean celebrations could spill over into the new year.
What’s so special, or so dismal, about thirteen anyway? It’s an odd number but so is seven, usually considered the luckiest number. It’s also a prime number but those are also supposed to be lucky, or at least have their own special appeal.
And thirteen’s not always unlucky. Unless you’re counting calories it’s lucky to get a baker’s dozen, especially if you’re ordering doughnuts, there are Thirteen Postures in Tai Chi, and many cultures consider thirteen to be the beginning of adulthood. It’s the beginning of the teenage years so, yeah, I can see why that would be considered unlucky.
The significance of thirteen may ultimately be lunar in origin, though. Most years have twelve full moons. A year with thirteen isn’t unusual but occurs about every three or for years, so whether you consider it lucky or unlucky pretty much depends on the kind of year you’ve had.