How can I convey dates (with ordering) for events happening under different dating systems, e.g. a Sci-Fi story spread over the galaxy?

Question

So I want to write a Sci-Fi where humans have spread across the solar system and into the galaxy. There are multiple stories going across at several different times. E.g.:

1. Aliens attack Pluto
2. 3 weeks later, aliens arrive at Mars
3. Flashback scene to a few years ago, when Earthlings missed sign of invasion, leading to destruction of Earth.

Currently, I'm using Earth dates, something like: July 28 (Earth date), aliens attack Pluto, August 20 move to Mars etc. But people on Pluto wouldn't use the Earth calendar; they would use their own system. When those people talk about dates, what should they say? How can I convey to my readers the dates of these various events (and the relationships among them) when the calendar systems used by the characters would be different?

PS: I don't want something confusing like the Stardate system. I don't want to be explaining to my reader how my calendar works.

Answer 1

I can think of a few ways:

1) Cheat. This was how Tolkien did it, so you'd be in good company. He just listed somewhere in the appendices that "Year 5798 by Gondor's calendar = 144 Shire Reckoning" and let the readers do the math.

2) Make the characters work out a solution. If you have characters on Terra and characters on Pluto who meet, they're going to have to work out some way of synching their calendars.

3) Meta. At the beginning of a chapter, just announce as part of the header what the date is:

July 20, 2056 Terran Time
12 Fizzbinth of Shar, Plutonian Time

If you equate them at the beginning of the chapter, it will be clear that the two dates are the same, and then you can advance them separately (or together) as needed.

4) Reset the calendars. Call it 1 A.I., Year one after invasion.

At some point, unless all your characters are using a calendar which your reader understands, you are going to have to do some amount of explaining.

Answer 2

If you are just using dates in narration, as opposed to in dialog, you could just use Gregorian dates. When an American or European writes a history book today, they routinely use the Gregorian calendar even if that's not the calendar used by the people they're talking about. This only matters if the date itself is significant to the subjects.

If the people on the other planets are colonists from Earth and not aliens native to that planet, it's quite possible that they WOULD use an Earth-based calendar. Especially if they're in regular contact with Earth people. Sure, the Gregorian calendar does not match the orbital period of Mars or Pluto, but the convenience of using the same calendar on all the planets in the solar system would likely outweigh any advantage of having the calendar match the orbital period. I think this is what most science fiction stories do: They just have the characters express time in "standard Earth years" and leave it at that. It's not implausible, because the same reasons that make it simpler for the reader would make it simpler for the people involved.

Of course if you're talking about aliens, I wouldn't expect aliens to use the Gregorian calendar. That would be a rather jarring disconnect.

So failing that, if for one reason or another you must have these people have their own calendar, I don't see how there is any way out of explaining it, at least to some extent. You can't just say that one event took place on the Third of Foo and another took place on the Lesser Mordac of Hegenev and expect the reader to somehow know which came first and how far apart they are.

Unless you want the workings of the calendar to be a major element of the story, even a simple calendar would be a pain to the reader. Like if you say that the Martian calendar has 20 months and here are their names, and the months are 33 days each except for the 2nd, 4th, 7th, 9th, 11th, 13th, 16th, and 17th, and the 19th on leap years, and leap occur two out of every five years, etc. (I believe that adds up to the right number of days, if I made a mistake, not really the point), that's about as simple as you're going to get, and it's an awful lot for a reader to understand and remember just so he can grasp when things are happening.

I think the easiest way out is just to translate the dates. As I said, if it's in narration, you can simply say, "this happened on August 3". What the date is on somebody else's calendar doesn't matter. If it's necessary for a character to say the date, you could translate. Like:

"We must do this by the High Mordac of Hegenev," Franslac said.

George did a quick translation in his head: That would be August 3.

Of course if you're doing this all the time, that could get tedious for the reader. That's why, I think, most writers avoid the problem.

Answer 3

From the point of view of practicality it's pretty hard for human beings from earth to adjust to other solar cycles etc. We're not built to operate in days much outside of our current 24 hour clock. People working in locations where the days are unusually long or short (or practically non-existent e.g. the South Pole) experience bizarre physiological and psychological effects.

For this reason most SF writers fudge the issue by referring to "Standard Cycles" or "Solar Days" or "Median Orbits". The nomenclature is alien enough to be exotic whilst clear enough to imply that time passes at the same rate. Star Trek is the exception not the rule. I think the "Stardate" thing was just a device to make the voyage of the USS Enterprise appear to be timeless and epic.

Answer 4

Focus on your storytelling and how you structure your narrative. This will bring clarity to the timeline more than the syntax of the calendar you end up choosing. Recall your favorite science fiction authors - the vivid world they created and character arcs were probably primarily what drew you in, more than the delight of the alien language or non-earthly systems presented.

Storytelling and structure are your "cake". The solar-system terminology you ultimately settle on will be the "icing" on that cake.