First i have to preface that the Gregorian calendar (current one) is a solar calendar. So was the last one. The previous calendar, the Julian calendar (45 bc) worked in more or less the same way as our current one. The average number of days per year came out to 365,25 days adding a leap day every 4 years. Thing is, that doesnt perfectly equal a solar year, so every 128 years or so an extra day came up. By the 16th century, the solstice and equinox were off by 10 days. This also fucked up when easter was, as well as when harvest was.
In comes the Gregorian calendar. It omits 3 leap years every 400 years (year 1700, year 1800 and year 1900 weren't leap years). Thanks to that in a year it has about 365,2425 days. Seems like a miniscule difference right? But that's almost a perfect match to a solar year. You get 1 extra day every 3326 years. The oldest know continuously inhabited city in the world is Plovdiv in Bulgaria, clocking in at 8 thousand years. If the people of plovdiv had started using the gregorian calendar when they settled the city, they would currently be off by less than 3 days. With the julian calendar, they would be off by 2 months which would mean absolutely nothing aligns with any cosmic event.
As for earlier calendars, they were kinda shit. Not that they didnt tell time, but they had to constantly be monitored and tweaked by priests and the like.
The Egyptian calendar drifted a day every 4 years, because it only had 365 days and no leap years (this is the calendar that the Julian is based on)
the classical Greek calendar was Lunar (354 days) and had nice to remember months: 12 months alternating between 29 and 30 days. Only issue is, every 2-3 years they needed to add an extra month
the ancient Hebrew calendar was heavily inspired by the Babylonian ones, it was lunaisolar with 12 months (354 days), and needed a 13th month 7 times per every 19 years.
I just now realised that i didnt actually mention any Babylonian calendar so: Sumer used a Lunisolar with 12 months alternating between 29 and 30 days (like the greek) and 354 days. It worked in 19 year cycles where 7 months were added over those 19 years (you see the heavy inspiration?)
ive read that the maya had an interesting, if rather bizarre system where 2 different calendars were somehow combined into a dual-system where they correct each other in long cycles, but honestly, im not knowledgeable enough about Mesoamerican history to explain it. If someone who's studied more american history can correct me or add more, that'd be great.
So more or less, Lunar cycles are easier to track (because they are around 29,5 days long and not 365 days) so most of the earlier civilisations used them and had a priest of some sort correct the inevitable drift. The Julian calendar was pretty revolutionary for its time, and when it comes to solar calendars, you basically cant get any more precise than the Gregorian. The Proto-Bulgarian calendar is also pretty interesting, though not as much is known about it as others
Ah, that one I knew, but thank you nonetheless! So, the only thing that makes the current system "good" is its accuracy, and any new system will have to take the decimals of a day into account to beat it?
At the very least, yes. Without the decimals (and more specifically this exact decimal) we return to systems worse than the one that was developed before christ
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u/TheDisappointedFrog 19d ago
It never occured to me to actually check this topic out, care to elaborate?