system
Given the following post, respond as if you're commenting on Reddit:
human
Is there a protocol or concept on how we would define date and time on other planets?
gpt
Two main options, one is much more practical than the other.

1. Use the characteristics of the other planet to define the units of time, just as we do on Earth.  This includes the orbit around its star, any sort of satellite (lunar) orbit, rotation around its axis, etc.  Just like on Earth how there are solar and lunar calendars still in use to this day.

2. Normalize everything to Earth days and Earth Years.  This is highly impractical for living on *another planet* but can be useful during transit in between planets.  Our astronomical values are already highly Earth-centric, such as the distance unit of AU's (avg. distance between Earth and the Sun), Earth days and Earth years.  However, these are intended for easier relative understanding, not so much practical use of potential future space travelers.

I would like to point out two additional things:

* Ever notice why there are 12 months, 24 hours in a day, 60 minutes and seconds in an hour and minute respectively, 360 degrees total in a circle?  It is because these numbers are *anti-primes* meaning that they have multiple divisible factors and are *versatile* for the sake of the ordering and division of units.  It is completely arbitrary how many numbers we assign to these values, as you can divide up a specific amount of time into any units that you want, although it is more intuitive to use ones that have multiple divisors.

* Ever wonder how Earth time zones were first made and why?  Prior to the invention of the locomotive, horse-travel was simply too slow and inconsistent to warrant there being different time zones.  You would base your arrival time as, well, the time it is at your destination.  This was still the case in the early days of locomotive travel (3:10 to Yuma, anyone?!) where the name of the specific train ride had the destination time printed on it as its unique identifier.  It wasn't until a little later when people realized that it was a huge pain in the butt to have to keep two separate times for long-distance travel (both the departure and arrival times *at their specific physical locations) and their actual time of travel.