Worldbuilding New Calendars

Fantastical calendars are a staple of science fiction and fantasy, and for good reason: a way of measuring time that differs from our own being prevalent really helps to immerse one into another world. Sometimes this applies to our very own Earth, which has produced a large variety of calendars, and often, even more interestingly, it applies to some other world altogether, be it a real-life one (e.g. the Darian calendar which has already found real-world applications for Mars rovers) or a fictional one.

New Calendars already in my Space Opera

In my space opera setting there already was a reference to a Martian calendar as early as my first novel “The Hunt for Count Gleichen’s Treasure”, in the form of Comet Siding Spring being referred to as the “Great Comet of year 27”, year 27 referring to the number of Martian years since the epoch of my setting’s Martian calendar, the first manned landing on the planet in (by our reckoning) 1962.

Aside from using Martian years I tell nothing else about the calendar, though presumably it uses Martian days instead of Earth days. Rather conveniently the Martian day is only slightly different from an Earth day, making it the most practical choice to denote periods of sleep and wakefulness for Martians. This the calendar will drift relative to Earth days. By contrast, on a planet of constant day or night or on a space habitat or spaceship the colonists would likely stick with whatever day reckoning they were accustomed to originally.

So it is with the colonists in the far future of my space opera setting, who primarily live on space habitats, the vast majority of whom flit between planets, solar systems, and galaxies as easily as we walk across the street. Ah, the wonders of warp technology. But this presents an issue for timekeeping, as there is no natural day or year to base a calendar off of. Thus it seems likely to me that the predominant calendar will be an Earth one; if there’s no one planet to synchronize yourself to then the ancestral homeworld of Earth is the obvious choice.

While I could have used the Gregorian calendar, and indeed did for the nearer-future 21st century stories, in the 4th millennium stories that would just be too dull and obvious. I keep any references to calendars in my far-future stories deliberately vague, but there is a passage in “Warp Dawn” where Lady Emma Hamilton’s time, our late 18th century, is referred to as “the turn of the epoch”, implying that the epoch the characters’ calendar use is around then rather than Anno Domini.

My Space Opera: using an American Revolutionary Calendar

And that implication would be correct. In the fullness of time after the 20th century an American Revolutionary Calendar developed and spread around the world, becoming the standard calendar of humanity.

This is an interesting contrast with the other part of the backstory, which has Russia become the leading civilization for basically the entire 3rd millennium similar to how western Europe rose in the 2nd; this is why Russian is the lingua franca in the 4th millennium out in space, much like English is now or Latin was back in the old days. The key to all this is that Siberia is the center of this Russian civilization of the future; Americans, particularly Russian-Americans, immigrating there en masse and being a formative influence could easily drive the culture to adopt some American characteristics. Siberia becomes the new America. It would be far from the strangest thing that’s happened in history.

Anyway, as the name suggests the American calendar’s epoch is the year of American independence, 1776. This isn’t as far-fetched as it might seem; the American Constitution denotes its year in both Anno Domini and the years since American independence, and a surprisingly large number of inscriptions in public buildings from the 18th and 19th century use that notation.

What seals the deal in my view is the vast majority of the Industrial Revolution and afterward, including the vast majority of the Liberal Revolution and the entirety of the French Revolution, being denoted with positive year numbers. It’s a more convenient epoch than the first nuclear test or the first Moon landing.

Personally I think this elevates 1776 above the 1792 epoch of the French Republican calendar, which by the way was an excellent and much-improved calendar that shouldn’t have been tossed onto the ash heap of history. Yes, I just like it and wish we adopted it or something very similar to it in real life, and that’s the real reason I bring it back in my space opera universe: because I like it.

Months in the Revolutionary Calendar

One of the calendar’s virtues is that months start in sync with the solstices and equinoxes, instead of having awkward ten day or so periods of time between them and the start of a new month. The new year in my version would start on the winter solstice; much more elegant than the status quo.

The month names are perfectly fine in French, but other nations should call them by analogous names in their own language or revive traditional names used before Christianity. In English we helpfully have a complete list of Anglo-Saxon month names. J.R.R. Tolkien used them in the (suspiciously French-Republican-like) calendar for the Hobbits of the Shire, appropriately updated to modern English.

January becomes Afteryule, February Solmath, March Rethe, April Astron, May Thrimidge, June Forelithe, July Afterlithe, August Wedmath, September Halimath, October Winterfilth, November Blotmath, December Foreyule.

So if we slot these names into the French Republican months and use 1776 as the epoch then today, August 4, 2021, would be Wedmath 17, 245 (in the original French version it would be Thermidor 17, CCXIX (229)). Cool, isn’t it? Why couldn’t the English-speaking countries have done something like that? Oh well. The future is yet to be written!

Obviously the “standard” versions of these months in my future is whatever names the Russian language would develop, but if I ever were to feature the calendar in my stories “translation convention”, rendering them as their English equivalents, would apply.

The new Week: unchanged and still in Parallel?

The fate of the week in the new calendar is a bit more nebulous, but unlike the French version I imagine the week system would continue in parallel to the main calendar as it is today, rather than being reformed. Pagan sensibilities come back to the fore, which lessens the importance of Christian worship as an objection to changing the week, but at least in English the week day names (not to mention the month names…) are all pagan anyway, so the current week would suit this future’s culture just fine.

Intraday Timekeeping in a new Calendar

Timekeeping within the day is also nebulous. In my head the characters in my far-future stories use the same clock we do, hence hours, minutes, and seconds still being things and meaning the same lengths of time, and all these time units are referred to in-text, though I could also chalk this up to translation convention. The French Republican Calendar used decimal time, with each day divided into 10 hours, each hour into 100 minutes, and each minute into 100 seconds.

Interestingly decimal time in the French Revolutionary era never caught on nearly as much as the annual calendar did; even at the height of the calendar’s usage 24-hour time remained the most prevalent form. On the other hand, China traditionally used decimal time, and cultures descended from there may well return to it in my future, possibly being the seed of a more general adoption of decimal time by the human mainstream.

The French version divided the day into 10 hours, which in our system amounts to 2 hours and 24 minutes, which seems almost like a step backwards in terms of convenience; we’d have to use a lot more fractional hours. A slicker take on decimal time is to divide the day into 100 parts, which each amount to 14.4 of our minutes, enabling whole numbers to be dominant for everyday scheduling. Some, perhaps most notably Joseph Charles Fran├žois de Rey-Pailhade in the 1890s, have proposed this approach, but it’s gained little traction.

For instance, twelve o’clock (12 PM) in our time would be five o’clock in 10-hour notation or fifty o’clock in 100-hour notation, eighteen o’clock (6 PM) becomes half past seven o’clock or seventy-five o’clock, and so on. Constructions like “ninety o’clock” might sound weird to us but I think it’s the kind of thing most people would like once they got used to it; 10-hour notation makes the hour less convenient, so if any such system is adopted in the future I’d bet on the 100-hour notation.

Personally if I were to include this in my new calendar I’d revive the archaic word “stound” to describe this unit. It was the original English word for “hour” before the Norman era, which makes it ideal for distinguishing a different system of hours. In my view it sounds better than “hour” in English to boot.

The curious History of Minutes and Seconds

Minutes and seconds have an interesting history. “Minute” comes from the Latin phrase “pars minuta prima”, meaning “first small part” (a different pronounciation of “minute” is a current English word meaning “small”). This system, apparently introduced by al-Bruni, subdivides each hour into sixty such “first small parts”. Each minute in turn is divided into sixty “pars minuta secunda”, “second small parts”, which is where the word “second” comes from.

Al-Bruni also divided each second into sixty “third small parts” and each third into sixty “fourth small parts”, but the second is the lowest such sexagesimal fraction still in use. In modern usage seconds are divided decimally, with the millisecond (a thousandth of a second) being the only subunit in common use outside scientific applications.

Ticks, Trices, and Beyond

Obviously in my new system each stound could be divided into 10 units that are each 1.44 minutes long, the decimal minute from the French calendar. Alternatively, and in keeping with the hundredths theme, each stound could be divided into a hundred units each 8.64 seconds long. A good name for such a unit might be a “tick”, as in the tick of a clock.

“Trice” is another older English term for a short moment in time. Alternatively, the name “first”, by analogy with “second”, might be employed, which arguably makes more sense than our current system. “Fifty firsts” might sound weird to us, but is it any weirder than “fifty seconds”? Still, I think “fifty ticks” sounds better, so I think I’ll go with that if I ever bring my new calendar into my space opera setting.

It’s well possible that the tick is the shortest unit of time in this system; at eight times longer than one of our seconds it’s a bit more unwieldy but not by much. Decimal subdivisions could be employed from there; a decitick is 0.864 seconds, a millitick is 0.00864 seconds, and so on.

If a shorter whole unit is desired, I think I would revive the term “trice” and make it a hundredth of a tick, going with the hundredths theme some more, with each trice amounting to 0.0864 seconds. In this case decimal divisions would go decitrice, millitrice, and so forth.

In this case, though, unless science switches to using ticks or trices as the base unit instead of the second there would be a whole parallel system of timekeeping used for scientific and historical purposes. Oh well, can’t win them all.

So in this calendar instead of Wednesday, August 4, 2021, 11:05:33 AM it would be Wednesday, Wedmath 17, 245, 46:21:87. Cool, isn’t it? That’s some stuff fit for a space opera universe.

Standard and not-so-exotic local Calendars

This will be more or less the standard human calendar, used to communicate dates and times across space and used as an everyday calendar for space habitat and starship dwellers. Planetary colonists will for their own purposes basically all have their own calendars in my setting, synchronized to local planetary and celestial movements instead of mother Earth.

What might that look like? On some planets the same units used on Earth work well enough with relatively minor adjustments. On Mars, for example, the local day isn’t much different from Earth’s, and the year is 669 days long instead of 365 days. The months of the standard calendar could simply be stretched from 30 days to 55 days and still describe the same seasons.

Exotic Calendars

More major adjustments are needed on other worlds, though. Take Neptune for example. A year that’s 165 Earth years long and a month that is 5,015 days long doesn’t seem all that practical, though they might just count them up for all I know. More likely, however, is subdividing these months, perhaps into tenths (501 days) or hundredths (50 days), for greater convenience.

Tidally locked worlds don’t have a solar day, but on their dark sides the movements of the stars will still be visible, in this case synchronized with the local year; these day-years tend to be short, especially on such worlds that orbit smaller stars, and they might be more or less arbitrarily grouped for convenience, or just counted up like Earth years are.

Lunar, planetary, and celestial cycles observable in the sky might be a big factor on some worlds. Planets with multiple large moons might be stimulated to use a lunisolar calendar with wondrously complex month systems. Planets in systems with a second sun that orbits closer in then further out would make these bright and dark seasons an integral part of their calendars.


That’s a really fantastic possibility! And there are so many more out there that I haven’t thought of for this post, undoubtedly all used in my space-opera setting. Maybe that’ll be my next project, writing a whole (short) book just about that, the standard calendar in my far-future space opera setting and examples of planetary calendars on these exotic worlds. That’s a thought!

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