this post was submitted on 04 Sep 2026
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Worldbuilding

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If humans one day conquer all of our solar system we might have settlements not just on Mars and Earth, but also in orbit of Venus or Mercury, and on the moons of the gas planets, like Jupiter's Europa. Each of those has a different length of day and year.

How would an interplanetary civilization find a common date and time system?

I assume each planet gets it's own local time, but I think a common date-time system would be usefull.

Also I don't like to just say, earth is human kinds origin, so it's time is the standard. Feels lazy.

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[–] HobbitFoot@thelemmy.club 1 points 3 weeks ago

If we are going to present Unix Epoch in a reasonable manner, do the following:

YYY/MM/DD HH:SSS

SSS is seconds from 000 to A23 (only use of alphanumeric). This gives you an amount where the next unit of "hours" is 2^10^ seconds, or ~0.28 hours.

HH is "hours" from 0 to 63. This gives you an amount where the next unit of "days" is 2^16^ seconds, or ~0.76 days.

DD is "days" from 1 to 32. This gives you an amount where the next unit of "months" is 2^21^ seconds, or ~0.81 months.

MM is "months" from 1 to 16. This gives you an amount where the next unit of "years" is 2^25^ seconds, or ~1.06 years.

YYY is "years" starting from Year 0 in Unix Epoch Time.

Expect that few people actually keep time this way unless they are forced to. Likely, the only people doing so are militaries that routinely have to coordinate with other militaries where a dominant time can't be agreed upon.

There could be an adjustment with the binary hours and binary days to get binary days close to terran days since a binary day is only ~18.2 hours long and that could be an issue with running a ship.