Hey, why is the solstice on 21 December?

Why is Christmas/Yule/Saturnalia a few days later? Why is the New Year a week and half later? Why is the 12th month called the 10th in Latin? Why are these dates all out of line with each other and scattered around?

It’s all because “the Romans had no fucking idea how to run a calendar”.

You think you’ve heard all the ad hoc arbitrariness about how the Romans managed their calendar as you’re led step by step through it all, and then you learn about Mercedonius and you just want to throw everything on the floor and walk away.


  1. SchreiberBike says

    I feel strongly about the World Calendar (https://en.wikipedia.org/wiki/World_Calendar). Its on my list of things to do after we take care of the little things (Nazis, Trump, hate, dehumanization, dignity, healthcare, racism, sexism, tribalism (it depresses me that I could probably keep typing for an hour), …).

  2. John Morales says

    Ordinal dates (yyyy.ddd) are better and easier for computation, but there’s no getting away from the physical reality; days and years are physical phenomena and there’s no equivalent of the metric system or the Kelvin scale for that.

    Sure, one could reset the zero point (“new year”) to some arbitrary point such as the solstice, but that would just be an esthetic preference without particular benefit.

  3. Mrdead Inmypocket says

    Wait, I meant 2018. Sorry I shouldn’t comment when I’ve taken my sleep medication.

  4. cartomancer says

    In contrast to the Romans’ somewhat chaotic approach to the official calendar, classical Athens had three calendars running simultaneously – a twelve-month lunar calendar for working out the dates of religious festivals, an official and arbitrary ten-month political calendar for regulating the cycle of democratic meetings and votes, and a solar agricultural calendar for determining when to plant and harvest.

    The lunar festival calendar was generally used by historians for recording events. The Athenian year began in mid summer (the month of Hekatombaion, traditionally when a sacrifice of one hundred cattle was offered to the gods), which is why dates in our histories of Athens are often given as two years – e.g Cleisthenes founded the democratic constitution in 508/7BC (we do not know the precise month, so we can’t determine which of the two years on our calendar it refers to).

    The Romans knew very well that the Greeks were much better at astronomy than they were. Vergil even says as much in his Aeneid, noting that others can do all the art and sculpture and science and public speaking, but the Romans are specially gifted in the arts of rulership and command. The Romans’ ad-hoc attitude towards the months of the calendar tells us some quite significant things about them. First of all, the year was the only really significant division of political time in Rome. Whereas the Athenians had a democratic system that mandated ten equal units of political time – ten prytanies, in which four regular meetings of the Ekklesia assembly were held and a different tenth of the presiding council (the Boule) was in formal charge of the state bureaucracy – the Romans just appointed their magistrates for a year and let them get on with it. There were no significant changes to mark other than the annual ones. Rome’s political meetings throughout the year (contiones) were generally not regular, because the majority of actual governance did not take place in them like it did in Athens (where all major decisions had to be referred to the assembly). The Senate remained in de facto charge of things in Rome for the most part. whether it was meeting formally or not.

    Secondly, the Romans were very pragmatic when it came to the dates of religious festivals, and regarded the whole business less as a solemn and sacred duty than as a piece of arcane business colleges of priests could get on with and everyone else could work around. The legislative year was very much fraught with irregularities caused by religious taboos, and these could be taken advantage of by ambitious politicians. For instance, there was a brief window in January when there were enough consecutive days to discuss and pass laws, and when it was over you generally had to wait until the autumn. Half of February was taken up with festivals, and the rest was highly inauspicious (nefas) for public business (the gates to the underworld were said to open in this month, explaining why it was associated with fevers, ill omens and bad fortune). When March rolled round the consuls and their armies would be mobilising for war (which is why the month was named after the war god), so political business would effectively be suspended until the end of the campaigning season. If you wanted to hamstring an opponent’s legislative programme during their consulship, you basically just had to filibuster or declare ill omens in January so that the time limit would run out, then work against them while they were away so it was much harder to return and get things done late in the year. Most Roman politicians seemed to quite like this arrangement, because it could be manipulated for personal gain, and so there were rarely serious calls for calendar reform to sort it out.

  5. cartomancer says

    Moreover, the Roman calendar is what you get when you organise your calendar based on notions of religious observance and superstition, rather than with any practical purpose in mind. It’s all about making sure festivals happen on the right days and avoiding inauspicious timings. That intercalary day that was introduced early on? Nothing to do with making sure the seasons were in alignment with the months (that was what the inchoate intercalary months were for) – no, it was to stop the kalends of January or the nones of any month from falling on a market day (nundinae). The kalends of January were avoided because if they fell on a market day it would be bad luck all year. The nones were avoided because the birthday of the archaic king Servius Tullius was supposed to have been on the nones, and that was an event of religious significance, though since nobody knew which month’s nones he was born on they put them all aside just to be sure.

  6. John Morales says

    Rob, chigau yeah. I was thinking too narrowly, and the lunar cycle is also important.

    (But, if we did that analogously, there’d be 13 28-day months in a year)

  7. Pierce R. Butler says

    cartomancer @ # 8: … classical Athens had three calendars running simultaneously… The Romans knew very well that the Greeks were much better at astronomy than they were.

    Which raises the question of which calendar Athenian astronomers used, and whether they invented a fourth.

  8. John Morales says

    Rob, convenience, esthetics. Calendrically, it would be more convenient. Esthetically, every month would have the same number of days and weeks precisely, with one left over at the end of the year, but it would be more regular and you would not need to memorise the different number of days each month has, monthly billing cycles would be of the same duration, etc. Leap day would be analogous to the leap second, but even more regular.

  9. says

    For some reason the linked page will not come up for me, so my apologies if this is explained there.

    It is my understanding that the Christian dates were set several centuries after the Julian reforms that made the calendar predictable. Christmas was set to December 25, and Easter was tied to an assumed vernal equinox on March 25, because back then those were the correct dates for the solstice and equinox. The earth’s axis “wobbles”, with the axis tracing out a cone over roughly 26,000 years. This wobble is not in sync with the earth’s orbit, resulting in a phenomenon called precession. Over 2000 years, the equinoxes and solstices have backed up five days. Heck, I remember 40 years ago when the equinoxes reliably fell on the 21st.

  10. vucodlak says

    @ chigau (違う), #18

    I am in favor of having a month named “Winterfilth,” provided I get to be born in it.

  11. robert79 says

    “The priesthood … would extend or contract years to keep politicians (who were on yearly terms) they liked in power or force politicians they didn’t like out early.”

    I am seeing possibilities here!

    Currently, the length of a year is decided by astronomers. Instead of haggling over whether we want to add a leap-millisecond or two, perhaps they could make the next three years REALLY SHORT!

  12. jacksprocket says

    Cartomancer@8: The Greeks were even more chaotic than the Romans. At least the Romans had one kludge for the whole empire. The Greeks had a different calendar- subject to arbitrary intercalations- for each city. Even the months – though largely the same names- varied from one place to another. So if the month was Loos in Antioch, it would be Daisios in Sidon and Gorpaios in Tyre (these were all Greek cities- Attica was only one part). Loos in Sidon was 2 months later, and a month earlier in Tyre.

    The Jewish calendar, Babylonian in origin, though lunar, has the advantage of a regular fix to pull the months back into correspondence with the seasons. It’s why Easter shifts about so annoyingly, though Hanukkah’s vagaries are quaint (to me) because I don’t have to put up with them.

    The totally lunar Islamic calendar is perhaps what you might expect from a nomadic community of herders in a climate without much annual day length variation and no real seasons.

  13. razzby says

    When my family shook off the last of our religious upbringing, we took a hard look at all the holidays. Is it based on a religious observance? Is there a secular side of the coin? If so, what is the motivation there? Commercialism? Human connection? Is there a good idea pushing the tradition or is this just another way to measure the passing of time?

    We suddenly found ourselves with a few extra days on our hands.

    But the solstices? Actual astronomical benchmarks? Hell, yeah.

    Plotting out the next year with calendars and goals, with a feast, a bonfire, some star watching, and with mulled wine and mead to keep frozen fingers at bay beats the high pressure winter season interface we knew before.

  14. says

    Of course the solstice is on the 22nd of December on the western side of the international date line, not the 21st as it is in the Late Countries.

  15. A momentary lapse... says

    I heard that the Romans even got the leap year thing wrong. They figured out (or got the idea from the Greeks or something) that they needed to put one in every four years, but they counted inclusively, so put one in every three years for a while. Not sure if that’s correct or not, but it would certainly fit with the rest of the nonsense.

  16. Rob Grigjanis says

    Gregory @19: My understanding is that Pliny the Elder nailed the solstice at Dec 25 in the first century. If the Julian calendar was used consistently until the Gregorian reform about 1500 years later, the precession error would have shifted the solstice date to around Dec 13. So there’s been more date fiddling somewhere. Anyone?

    Anyway, since then it would have been much more stable, since the Gregorian calendar matches the seasons quite accurately.

    A momentary lapse @27: I think the Romans fixed that.

  17. Rob Grigjanis says

    Silly me @29: If I’d read more of that first link, I’d have been less confused. My bolding;

    In 1545, the Council of Trent authorized Pope Paul III to reform the calendar, requiring that the date of the vernal equinox be restored to that which it held at the time of the First Council of Nicaea in 325 and that an alteration to the calendar be designed to prevent future drift. This would allow for a more consistent and accurate scheduling of the feast of Easter.

    That probably answers my question.

  18. petesh says

    Hmph. We have a lot of nerve criticizing Our Illustrious Ancestors (the guys with long white beards and statues) when we screw around with the time of day. Our future overlords in China do not (clearly a source of their growing power) but they do insist on one time for the whole country, which is very rough on people who work at Post Offices and other government buildings in Tibet, who (used to and I think still) have to go to work on Beijing time, i.e. when it’s four in the bloody freezing morning.

  19. lumipuna says

    Rob Grigjanis @30: If the real solstice was around Dec 21 in the early 4th century AD, I figure it’d have been around Dec 23-24 in Pliny’s time. Close enough, I guess.

  20. shadow says

    According to the Discordian calendar:

    Today is Sweetmorn, the 64th day of The Aftermath in the YOLD 3183

  21. busterggi says

    And here I thought it was because that was the only day the solstice had to make an appointment.

  22. blf says

    The mildly deranged penguin giggles at this insistence that days and orbits and months have something to do with the Sun, the Massive Orbital Cheese Vault†, and so on. The Earth does roll around the Sun, but uses an old experimental design which is constantly breaking down, requiring expensive maintenance: A channel is craved through the aether every so often ahead of the on-rolling Earth, allowing it to keep on rolling around. The interval between each channel-craving defines a “year”. That interval varies in duration due to contract negotiations, strikes, delays in paying bribes, lack of spare parts, and the occasional Dalek.

    The aether-free channel is why the Michelson–Morley experiment failed to detect any aether, it’d all been shoveled out of the way beforehand.

    “Weeks” are a purely local invention of the priests so they easily remember the decreed tithe-paying days (e.g., start / end of each week…). And those “days” are the result of faulty electrics — the rolling Earth keeps loosing contact with the power mains.

    “Months” simply make no sense at all, with the folk belief it’s a measure of how long you should brush your teeth each day being as plausible as any other origins explanation.

      † The common MOON acronym is the result of exceptionally bad stylusmanship.