In the history of the world I am building, there is a big time spam, divided by some important events that changed the course of human history many times.


At first, we have these two ships that parted from a lunar base to a planet hundreds of lightyears away, using speeds that could almost hit the speed of light. Both ships had planned they course and had determined the exact date of arrival in Julian Days and Universal Time. The first would start the colonization and the second would come with the rest of the remaining population.

The problem was that the first ship passed through a space anomaly that strongly bent space-time and made it go directly to its system destination, but at an speed so incredible that not even light could compare to it, making it go back in time.

To be more precise, it arrived in its destination before the humans even existed in Earth, something like 3.0 million years ago.

They settled, build the colonies and time passed.

The problem is: What can I use as calendar for the period before the second ship arrives if Julian Days start in 4714 BC? The humans on the new planet need a new way to count time, something not relative to Earth or the Solar System. After the second ship arrives(in the determied date) the calendar will be based on Julian Days as it is the standard calendar used for space exploration.

Thousands of years after the second ship arrival, the calendar is readjusted to reflect a new type of time unit based on a pulsar located somewhere near the system.

Sorry for any typos, english is not my mother language.

  • 3
    Perhaps a little simple, but what about Since Settlement? So 4500 years since they landed would be 4500 SS. On a random note, considering that our perception of time and our calendar is based on Earth years, will your new planet have the same orbit time?
    – CLockeWork
    Mar 26, 2014 at 13:26
  • Related; not quite a duplicate but probably useful: writers.stackexchange.com/questions/7394/… Mar 26, 2014 at 16:54

1 Answer 1


As we've seen on earth, communities count time in reference to key events -- the creation of the world, the birth of a new religious figure, the beginning of a king's reign (these ones have less staying power), and so on. When calendar systems encounter each other (I say the year is 5774; you say it's 2014; now what?), some sort of reconciliation happens.

If your colonists have the notion of a 24-hour day regardless of the solar events they're now experiencing, and if they know they went through a time-warping anomaly, then it's not unreasonable for them to start counting in those days from that event. So they arrive in, say, year 1, month 10, day 3 AA (after anomaly), and go from there.

If they don't know they went through an anomaly, then nothing changes for them -- they count time as they always did. That they're wrong isn't known to them, only to the reader.

Either way, if they went millions of years into the past and there's no relevant tech magic, they'll live the rest of their lives never having to reconcile their calendar. The reader, on the other hand, will be tracking a story with two timelines and two dating systems, but this probably isn't a burden because those timelines don't interact. Plus, we've all read stories told partially in the present and partially in flashbacks without getting confused about time; this is similar.

  • Interesting, very interesting. I understand and like your point. Well, as they, after some research, realize that the space-time travel happened and they are somewhere in the past, I think I will have to use your idea of an AA (after anomaly). People wouldn't use any already know human calendar system as they're completely cut off of their timeline and location. We could guess they started a convention and introduced a new calendar system, based on the planets astronomy and geography, and their arrival. Mar 26, 2014 at 14:15

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