cross-posted from: https://lemmy.world/post/19541930
Preferably a Holocene colander?
A consensus view was formally adopted by the IUGS in 2013, placing its start at 11,700 years before 2000 (9701 BC), about 300 years more recent than the epoch of the Holocene calendar.[6]
Some problems with Gregorian calendar
The Gregorian calendar improves the approximation made by the Julian calendar by skipping three Julian leap days in every 400 years, giving an average year of 365.2425 mean solar days long.[82] This approximation has an error of about one day per 3,030 years[s] with respect to the current value of the mean tropical year. However, because of the precession of the equinoxes, which is not constant, and the movement of the perihelion (which affects the Earth’s orbital speed) the error with respect to the astronomical vernal equinox is variable; using the average interval between vernal equinoxes near 2000 of 365.24237 days[83] implies an error closer to 1 day every 7,700 years. By any criterion, the Gregorian calendar is substantially more accurate than the 1 day in 128 years error of the Julian calendar (average year 365.25 days).
In the 19th century, Sir John Herschel proposed a modification to the Gregorian calendar with 969 leap days every 4,000 years, instead of 970 leap days that the Gregorian calendar would insert over the same period.[84] This would reduce the average year to 365.24225 days. Herschel’s proposal would make the year 4000, and multiples thereof, common instead of leap. While this modification has often been proposed since, it has never been officially adopted.[85]
On time scales of thousands of years, the Gregorian calendar falls behind the astronomical seasons. This is because the Earth’s speed of rotation is gradually slowing down, which makes each day slightly longer over time (see tidal acceleration and leap second) while the year maintains a more uniform duration.
Calendar seasonal error Gregorian calendar seasons difference
This image shows the difference between the Gregorian calendar and the astronomical seasons.
The y-axis is the date in June and the x-axis is Gregorian calendar years.
Each point is the date and time of the June solstice in that particular year. The error shifts by about a quarter of a day per year. Centurial years are ordinary years, unless they are divisible by 400, in which case they are leap years. This causes a correction in the years 1700, 1800, 1900, 2100, 2200, and 2300.
For instance, these corrections cause 23 December 1903 to be the latest December solstice, and 20 December 2096 to be the earliest solstice—about 2.35 days of variation compared with the astronomical event.
Proposed reforms The following are proposed reforms of the Gregorian calendar:
Holocene calendar
International Fixed Calendar (also called the International Perpetual calendar)
World Calendar
World Season Calendar
Leap week calendars
Pax Calendar
Symmetry454
Hanke–Henry Permanent Calendar
Other planets are going to likely need 2 calendars.
They’re of course going to need to keep track of the local day/night cycle, seasons, etc.
But we’re also going to need a universal calendar to keep things in sync between different planets, and that’s probably going to be the Gregorian calendar or whatever earth is currently using.
If you’re born on another planet, and that planet goes around its star 18 times, or spins on its axis 6000-some times, that doesn’t mean you’re biologically an 18 year old adult, that planet’s year and days could be significantly longer or shorter. So things like people’s ages are going to have to be figured in equivalence to earth years.
We’ll also need a coordinated time/calendar for interplanetary travel/commerce/communication. If Mars needs something delivered from the Europa colony by X time/date, and to deliver on that Europa needs materials from some remote asteroid mining outpost by Y time/date, they need to be in agreement on what that all means. Mucking around with mars years and days vs jovian years and Europan days, and whatever passes for days and years for an asteroid tumbling around in the belt is sure to lead to headaches. Better to have that all working on one system, and since humans across the federation/empire/whatever are already keeping track of earth years we might as well just use that instead of coming up with a third system for everyone to keep track of.
We don’t really know the effects of accelerated or slowed day/night cycle on humans in the large scale. Given the adaptive nature of humans / most biology on Earth, it’s not unreasonable to think that different planet’s cycle (from birth) might affect those humans in a profound way.
We also don’t have any particular reason to think that it will
Also, on Earth we already have situations near the equator where there’s not really a significant change in the weather from one season to the next, or near the poles where for parts of the year days are considerably longer/shorter than elsewhere on the planet, we also have people living in scorching deserts and frozen tundras, at high altitudes with thinner atmosphere, etc. and despite all that variation we don’t really see major differences in how quickly children mature.
The differences could be even more profound on other planets of course.
There have also been studies where people have lived in caves or bunkers without natural light, clocks, or other cues about the time or day/night cycle, and it’s been found that we stay pretty close to a 24 hour circadian rhythm (usually slightly longer actually, but within a few hours of that target,) so it seems like that’s something that might be hard-coded into us. Of course those studies have been done on adults who have had decades to acclimate to a 24 hour cycle, so it’s plausible that kids raised in a different environment would naturally adapt to a different cycle, but since we’re probably not going to be sending unaccompanied minors to the stars, those same kids would probably be raised by adults who are used to a 24 hour schedule and would raise those children in the same schedule.
You might see some divergence from that over the years and multiple generations, but if there’s a 24 hour clock present, and people decide to stick to that, I suspect that would work just fine. It would probably come down to whether it’s more beneficial for people to be in sync with the rest of humanity, or to be on the local cycle. My money’s on the former, since we probably aren’t going to need to worry about hunting for sustenance or avoiding predators, or other such things that our circadian rhythms evolved for.
Something we can’t really account for though is if different gravity would affect how quickly children mature. It will almost certainly have an effect on how they mature with differences in height and muscle/bone density, but I don’t think we can really say if it will change how quickly their brains develop, when they begin puberty, etc.
There’s other factors that could play a part as well of course, the composition of the atmosphere, the intensity of radiation from the star you’re orbiting, diet, exercise, different mutations that could arise over the generations.
Doesn’t matter as long as it’s useful
Secular vs Religious calendar is just a function of branding.
Unix Epoch time would be religious to some, there is no way to make everyone happy, but we can at least make everyone unhappy.
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Probably Terran Standard. Whatever that is at the time.
Until there’s a rebellion and they break away from Earth control.
That makes me wonder if any sci fi series use enacting a local planetary time systems as a major part of a political declaration of independence from earth central authority.
It’s not Earth-focused, but Eve Online had a minor subplot about how the coordination of time between multiple competing human civilizations became a major political problem because no one wanted to accept the system promoted by a rival empire.
I think that was in The Moon is a Harsh Mistress, iirc
I don’t think that timekeeping is an important subplot, if at all, but i could be wrong.
The supercomputer, though…
It’s the symbolism. Of taking authority over their own lives back from the central authority.
Doesn’t really mean much in a practical sense. It’s more about making the people feel more empowered.
I recently read an interesting book called “the mimicking of known successes” which is a mystery/romance novel but the scifi world building is the part I most found interesting. Humanity had colonized Jupiter, but ultimately died out on earth due to complete ecological collapse. Anyways on the timekeeping subject they didn’t really talk much about time, but it was noted that inhabitants experience 2 day/night cycles per regular earthly circadian cycle, and people will generally end up on sleeping for 1 day/night cycles and being awake for 1 day/night cycle and people can be on different cycles entirely, so presumably time is tracked within a cycle and people just sleep through every other cycle
Humanity had colonized Jupiter
You mean orbital space stations?
Yes it was specifically human-made rings around the planet with platforms built on the rings for the human cities and factories and farms and trains running between the platforms. They also specifically burned the gas from the planet’s atmosphere to generate energy as well as produce atmosphere for breathing
Manuel O’Kelly-Davis would like a word.
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The effect will be so minimal you can just ignore it. If needed it would probably be something handled akin to leap seconds vs something everyone is made to deal with constantly.
Very optimistic of you to think we will be around long enough to colonize other planets. We’re digging our own grave ignoring climate change the way we are as a species.
If we do make it that far, I imagine we’ll diverge from our homeworld and use whatever is convenient for us if we ever become self sufficient.
I don’t get why exactly the calendar needs to change? Because the seasons don’t line up any more? I suppose over thousands of years the expectation when winter is happening will have moved as well. Or is it because days and years won’t match with other planets? That’s not something a calendar can fix.
I would think seasons are the driving reason for an adjusted calendar. Any rotational tilt from the orbital plan will induce seasons. Every planet in our system has seasons, even the gas giants. That will have a cyclical effect on climate. Even in a sealed habitat, thermal regulation and solar power will be affected. The local year will also have an affect on interplanetary travel because, spatially, a day of the year is a specific place in space rather than a specific time. So a local calendar would provide a conversion.
As for a universal calendar, you’re right that it doesn’t fix anything. Instead of a calendar that works in one place and not 999 other places, a universal calendar would “not work” in 1000 places and work correctly in zero places. We already do something similar with global/space operations: make everything UTC time zone. While yes, it’s practically just prime meridian time, it doesn’t do daylight savings.
it doesn’t do daylight savings.
And that’s a blessing.
You imply that there is some sort of Solar Empire enforcing this. What will happen is the colonies will eventually come up with their own calendars and time system that reflects their own planet’s rotation, seasons and diurnal cycle. This is the human way and is inevitable.
hopefully we’ve already switched to a perennial calendar (preferably something like an ISO week date calendar (a variation of a leap week calendar)) by that point which would make things a lot easier to adapt to a new situation …
*every programmer starts sweating*
I prefer the way Mars lacks a calendar. Due to us placing a lot of stuff there, we need to refer to dates. Basically, the system just refers to days as Sol, and each individual date is Sol 1, Sol 2, and so forth until the end of the year. I don’t see why this wouldn’t work on other planets as well. Months don’t really serve a practical function anyway.
I think months, or some grouping of days is very useful. It’s harder to understand something like “days 90-120 in the northern hemisphere are usually good times to plant seed” or “I love the weather in New England around days 240-280”. Months and seasons give context faster than doing some internal mapping of day numbers.
Green Day probably wouldn’t be happy about rewriting their song to “Wake Me Up When Days 244 to 273 Have Ended” either.
Seasons still play a part. While Green Day would have to sort out the cadence for the rewrite, referring to fall would make sense instead.
They’d have to triple their sleep though.
If they can sleep for one month, they can sleep for three
What’s a month? ;)
I like it. Months are useful on Earth, but their absence in other planets’ calendars will go a long way to simplify things. Seasons can remain a function of Sols with periodic corrections over centuries to account for rotational speed changes.
Months are useful on Earth
Are they? I’ve found them to be the least useful division of time. They don’t line up with the days of the week, or the phases of the moon, or the seasons, and you need a mnemonic to remember which ones have 28, 30, or 31 days. Now if we had 13 months, each with 28 days, that could be a bit more useful…
It makes budgeting easier, for one. But it’s just a really arbitrary way to have a measure when a week is too little and a season / year too much.
It makes budgeting easier
I suppose so, but it would be even easier if months all had a fixed number of days, wouldn’t it?
those damn romans, man…
one month would need to be more flexible for the division remain and leap years, but it would I suppose.
flexible for the division remain and leap years
They’ve already got a plan for this. 13 months, each with 28 days (four weeks), gives us 364 days. New Years Day and Leap Year Day are added as extra holidays which are outside of the named day/month system.
Just stick to Swatch internet time, it’ll be fine.
Or something based on Science! Whatever depends on the planet’s rotation i guess… don’t need to go that far, Mars has an extra half-hour or something, good training ground.
Instead of trying to synchronize the year with the solstices, which vary unpredictably over time, just have every planet’s year start when it passes between its sun and the center of the galaxy. That will depend only on the orbit’s period, which is more consistent over time.
Not all planets pass directly between their star and the centre of the galaxy. The plane of our own solar system isn’t lined up with the plane of the galaxy, for example. If the Sun were attached to Sagittarius A* by a thin cotton thread, I’m pretty sure none of the planets would hit it.
We’d perhaps have to define it as the centre of the planet crossing the unique plane that both passes through the star and the centre of the galaxy and is perpendicular to the planet’s orbit relative to the star. And for some planets in some systems that would still be hard to calculate on account of an extremely oblique crossing angle.
And even then there might be severe problems with that for systems closer to the galactic core that are stable, but otherwise weirdly affected by nearby gravitational effects.
Also, what about planets that are far enough out to orbit two stars? Do we switch to barycentres and which do we use?
And what about moon dwellers or binary planetary systems? Pluto and Charon orbit a point that is outside both. There are further complications there.
We’d perhaps have to define it as the centre of the planet crossing the unique plane that both passes through the star and the centre of the galaxy and is perpendicular to the planet’s orbit relative to the star.
I’d rather define it as the point where a ray from the star through the planet crosses the pole passing through the galactic center perpendicular to the plane of the galaxy. Make it depend as little as possible on the planet’s orbital characteristics. (And yeah—use barycenters for binary stars and planets.)
That’ll be a problem for that one system that’s at right angles to the plane of the galaxy, but I suppose it could work otherwise.
I can also envisage situations where systems that are close to being at right angles to the galactic plane have the different star-planet lines cross the galactic polar line at opposite sides of the star due to slight variances in relative orbital plane. None of our planets are exactly aligned that way, for example.
Perhaps that’s not a concern though.
Given the dynamic nature of planetary orbits and the motion of stars around the galaxy, edge cases likely won’t stay edge cases for long—so predict ahead to see how the case will eventually resolve itself, and use that solution preemptively.
Stardate.
