Friday the thirteenth happens twice in 2023
As we speak is January 13, 2023, and it’s a Friday. And it’s the primary of two Friday the 13ths in 2023. There’ll be one other one in October. Does that imply 2023 is tremendous unfortunate? No. Any calendar yr has not less than one – however not more than three – Friday the 13ths. The final time we had just one Friday the thirteenth in a calendar yr was in 2022. And the following time received’t be till 2025. Are you petrified of Friday the thirteenth? Or has it simply bought a nasty rap? It’s actually only a characteristic of our Gregorian calendar, and a reasonably frequent one at that.
We final had three Friday the 13ths in 2015, in February, March and November. We’ll have three once more in 2026.
There’s a reputation for having an irrational concern of Friday the thirteenth: friggatriskaidekaphobia. Not that we at EarthSky endure from this concern … however, gosh darn, this yr’s first Friday the thirteenth on January 13, 2023, occurs precisely 39 weeks (3 x 13 weeks) earlier than the second Friday the thirteenth in October 2023. And that’s not the tip of it.
Subsequent yr, in 2024 (which additionally has two Friday the 13ths), the primary of the 2 comes on September 13, 2024, precisely 13 weeks earlier than the second Friday the thirteenth in December 2024. Then the only Friday the thirteenth of 2025 falls on June 13, 2025, precisely 26 weeks (2 x 13 weeks) after the December 2024 Friday the thirteenth.
Yikes, that’s fairly a couple of of coincidences involving the quantity 13 … although we may cite many extra!
Why do some folks concern Friday the thirteenth?
Are all these 13’s a scary coincidence or is it tremendous unfortunate? Neither. It’s only a quirk of our calendar, as you’ll see as you retain studying.
The actual fact is that, based on folklorists, there’s no written proof that Friday the thirteenth was thought of unfortunate earlier than the nineteenth century. The earliest recognized documented reference in English seems to be in Henry Sutherland Edwards’ 1869 biography of the composer Gioacchino Rossini, who died on a Friday the thirteenth.
Unfortunate? I do not assume so. The thirteenth is extra more likely to be a Friday than some other day of the week! https://t.co/aKfOawx8w7 pic.twitter.com/Che7xmZJrv
— Nick Berry (@DataGenetics) October 13, 2017
Has Friday the thirteenth bought a nasty rap?
Friday has at all times gotten a nasty rap no matter its quantity within the month. Even within the Center Ages, folks wouldn’t marry – or set out on a journey – on a Friday.
There are additionally some hyperlinks between Christianity and an ailing affiliation with both Fridays or the quantity 13. Jesus was mentioned to be crucified on a Friday. Seating 13 folks at a desk would supposedly convey unhealthy luck as a result of Judas Iscariot, the disciple who betrayed Jesus, was the thirteenth visitor on the Final Supper. In the meantime, our phrase for Friday comes from Frigga, an historic Scandinavian fertility and love goddess. Christians known as Frigga a witch and Friday the witches’ Sabbath.
In trendy instances, the slasher-movie franchise Friday the thirteenth has helped preserve friggatriskaidekaphobia alive.
The whole lot We Know About The New #FridayThe13th Present ‘Crystal Lake’ So Farhttps://t.co/TGCVDkaD6y
— Friday The thirteenth: The Franchise (@F13thFranchise) November 24, 2022
In 2023, blame a typical yr beginning on Sunday.
Each time a typical yr of 12 months begins on a Sunday, it’s inevitable that the months of January and October will begin on a Sunday. And any month beginning on a Sunday at all times has a Friday the thirteenth. So this yr, in 2023, we’ll have a Friday the thirteenth in January and October.
The final time a typical yr began on a Sunday was 6 years in the past, within the yr 2017. Earlier than that, it was within the yr 2006. This marked the primary time within the twenty first century (2001 to 2100) that New Yr’s Day began on a Sunday.
A few of chances are you’ll marvel if there’s some system that governs how this twofold Friday the thirteenth drama repeats itself. The reply is a particular sure. Remember the fact that this January-October Friday the thirteenth yr can solely occur in a typical yr of 12 months, and when January 1 falls on a Sunday.
Any calendar yr that occurs three years after a intercalary year will recur in cycles of 11, 22 and 28 years. Subsequently, if our twofold Friday the thirteenth yr comes three years after a intercalary year, because it does in 2023, the times and dates will match up once more in 11, 22 and 28 years. So the years 2034, 2045 and 2051 will all harbor January and October Friday the 13ths:
2023 + 11 = 2034
2023 + 22 = 2045
2023 + 28 = 2051
Calendar for 2023
How typically does a Friday the 13t occur in January and October?
Extra typically than you may think! The primary January-October Friday the thirteenth yr within the twenty first century (2001 to 2100) occurred in 2006, which is 2 years after a intercalary year. Any calendar yr occurring two years after a intercalary year can have days and dates matching up once more in intervals of 11, 17 and 28 years:
2006 + 11 = 2017
2006 + 17 = 2023
2006 + 28 = 2034
Subsequent, we proceed the cycle onward to discover a grand total of 10 January-October Friday the thirteenth years for the twenty first century (2001 to 2100):
2006, 2017, 2023, 2034, 2045, 2051, 2062, 2073, 2079 and 2090
As a result of the yr 2090 is 2 years after a intercalary year, we may be tempted to venture the following January-October Friday the thirteenth to the yr 2101:
2090 + 11 = 2101
Looking forward to twenty second century
Alas, right here’s the place the Gregorian calendar throws a monkey wrench at us. And by Gregorian calendar rules, century years not equally divisible by 400 (e.g. 2100, 2200, 2300) usually are not leap years of three hundred and sixty six days – however somewhat, frequent years of 12 months. So the suppression of the intercalary year in 2100 perturbs the cycle, bringing concerning the first January-October Friday the thirteenth yr of the twenty second century (2101 to 2200) within the yr 2102, as an alternative of 2101.
By success, we are able to fake that the yr 2102 comes two years after a intercalary year, to venture the recurrence of January-October Friday the thirteenth years in intervals of 11, 17 and 28 years.
2102 + 11 = 2113
2102 + 17 = 2119
2102 + 28 = 2130
We proceed the cycle onward to discover a total of 11 January-October Friday the thirteenth years for the twenty second century (2100 to 2200):
2102, 2113, 2119, 2130, 2141, 2147, 2158, 2169, 2175, 2186 and 2192
And the twenty third century
Within the twenty third century (2201 to 2300), the cycle is perturbed once more. The primary January-October Friday the thirteenth yr doesn’t fall in 2203 – however somewhat in 2209, which is one yr after a intercalary year. Any calendar yr occurring one yr after a intercalary year recurs in 6, 17 and 28 years.
Thus, we discover 11 January-October Friday the thirteenth years for the twenty third century (2201 to 2300):
2209, 2215, 2226, 2237, 2243, 2254, 2265, 2271, 2282, 2293 and 2299
And the twenty fourth century
Then within the twenty fourth century (2301 to 2400), the cycle is once more perturbed. The primary January-October Friday the thirteenth yr doesn’t are available in 2310 – however somewhat in 2305, or one yr after a intercalary year. That provides 11 January-October Friday the thirteenth years for the twenty fourth century (2301 to 2400):
2305, 2311, 2322, 2333, 2239, 2350, 2361, 2367, 2378, 2389 and 2395
As a result of the yr 2400 IS a intercalary year of three hundred and sixty six days, the cycle is NOT perturbed within the following twenty fifth century (2401 to 2500). So we are able to carry on going to seek out 10 January-October Friday the thirteenth years for the twenty fifth century (2401 to 2500).
2406, 2417, 2423, 2434, 2445, 2451, 2462, 2473, 2479 and 2490
Rhyme and purpose for the 400-year Friday the thirteenth cycle.
As a result of the Gregorian calendar has a 400-year cycle, the January-October Friday the thirteenth years recur in cycles of 400 years. For instance, respective January-October Friday the thirteenth calendar years are precisely 400 years aside within the twenty first and twenty fifth centuries:
twenty first century (2001 to 2100):
2006, 2017, 2023, 2034, 2045, 2051, 2062, 2073, 2079 and 2090
twenty fifth century (2401 to 2500):
2406, 2417, 2423, 2434, 2445, 2451, 2462, 2473, 2479 and 2490
Gregoriana cycle of 372 years.
It seems as if cycles of 372 and 400 years (372 + 28) prevail over the lengthy course of centuries. Take the yr 2023, for example:
2023 + 372 = 2395
2023 + 400 = 2423
The 372-year interval is called the Gregoriana eclipse cycle, which we elaborate about in our publish How often does a solar eclipse happen on the March equinox?
As magical as all of this Friday the thirteenth calendar intrigue seems to be, it’s not supernatural. But it surely’s entertaining quantity play, even when it could hang-out our uncomprehending minds.
Friday the thirteenth, by the numbers | @DataGenetics https://t.co/ET7kqCAqY4
Picture through: https://t.co/5GcrRV6nC9 pic.twitter.com/r3IuwSmnkz— VMware Tanzu Information (@VMWareTanzuData) November 13, 2015
Can a intercalary year begin on a Sunday?
Sure, a intercalary year of three hundred and sixty six days can begin on a Sunday. It final occurred within the yr 2012 and can subsequent occur in 2040. Any intercalary year beginning on a Sunday has three Friday the 13ths which fall in January, April and July. The times and dates of any intercalary year match up once more in intervals of 28 years. So we now have solely 4 January-April-July Friday the thirteenth years within the twenty first century (2001 to 2100):
2012, 2040, 2068 and 2096
Backside line: Petrified of Friday the thirteenth? It’s only a characteristic of our Gregorian calendar, and a reasonably frequent one at that. And from what we’ve been in a position to collect, the 400-year cycle displayed by the Gregorian calendar options 688 Friday the 13ths.
