Star Wars Time Measurement and Dating Systems

Question

I seem to remember several dating systems mainly in the Star Wars Expanded Universe. Furthermore, I was wondering if periods of time such as seconds, days, or months represent the same amount of time as they do in the real world.

So these are the main points of this question:

1. Which are the different dating systems (if there is indeed more than one) in the Star Wars galaxy? How are they related in regard to time offsets and such? (e.g. One system's year 5000 is another's year 268) An explanatory timeline graphic - perhaps including some important events - would be especially appreciated!

2. Do amounts of time in the dating system(s) such as minutes or hours represent the same amount as in the real world? If more than one system exists, do the amounts of time carry over between them? (e.g. 1 minute is the same amount of time in all systems.)

3. If the times carry over (or there is, in fact, only one system), what planet are the units of time based on? Coruscant?

Sorry if it seems I have asked too much in one question - splitting this question up into multiple questions did not appear to be a good idea as much of its content is very related.

Thanks for your time!

Answer 1

1. Almost everything about Star Wars is based on the Galactic Standard Calendar which uses the Battle of Yavin as its epoch (year 0). There are various other epochs, for instance, the formation of the Galactic Empire. There is a comprehensive text timeline here
   
   • BBY stands for Before the Battle of Yavin, and ABY stands for After the Battle of Yavin. (The Battle of Yavin ended with the destruction of the first Death Star, or if you prefer, the end of Star Wars Episode IV: A New Hope).
2. As for the time, there's nothing to indicate how it's related to earth's time, it just said that it's 24 hours = 1 day, 60 minutes = 1 hour, and 60 seconds = 1 minute.
   As for the calendar, it's slightly different from ours:
   • A standard week is 5 standard days
   • Each month is exactly seven weeks. (Making 35 standard days each month.)
   • A standard year was 368 days, and was composed of:
     • Ten months (350 days)
     • Three festival weeks (15 days)
     • Three holidays
3. Yes, Coruscant Solar cycle

The Galactic Standard Calendar was the standard measurement of time in the galaxy. It centered around the Coruscant Solar cycle, which was 368 days long (one day consisting of 24 standard hours). Numerous epochs were used to determine calendar eras. The most recent of these calendar eras used the Battle of Yavin as its epoch, or "year zero." BBY stands for Before the Battle of Yavin, and ABY stands for After the Battle of Yavin

Answer 2

Dates

In the new Disney canon, there are many dating systems, only two of which have been described:

1. Leland Chee, a creative executive with Lucasfilm, noted on Twitter in late 2016 that one such calendar, used exclusively by Rebels, is the ABY/BBY system from Legends, which takes the climax of A New Hope as year 0:

   

   @c_gibbs1000: Does the BBY and ABY year designations apply in 'Canon' as it did in 'Legends'? Much appreciated.

   @HolocronKeeper: It is one of many in-universe calendars. Out-of-universe, it makes more sense to use those years with the BSW4/ASW4 acronym.

   @HolocronKeeper: As to who would use it in-universe, it wouldn't be any non-Rebel and it couldn't be used before BY.

   He was asked the question again a few days later, and remarked that it wasn't a commonly-used system:

   

   @JediSAS: Does/will official canon have a dating system the way Legends canon did (BBY/ABY)? [...] Crap, I forgot to specify that I'm wondering about an in-universe dating system. Oops.

   @HolocronKeeper: ABY/BBY is one of many. Few would actually use and accept that one as standard.

2. The canon reference book Star Wars: Absolutely Everything You Need To Know reveals that the planet Lothal had its own calendar system. The only thing known about it is that the Empire was founded in 3258 LY:

   

   This calendar is presumably based on the length of Lothal's orbit around its star; it's unknown how that relates to Coruscant's orbital period, so equating the two calendars is impossible.

   It's unknown whether Lothal retained this calendar throughout its Imperial history.

Times

In an episode of Rebels Recon, a behind-the-scenes show for Star Wars Rebels, Pablo Hidalgo revealed that planets synchronize their timekeeping with Coruscant:

Andi Gutierrez: Nolan Jiminez asks: "How is time measured in the galaxy if each planet has a different time of rotation and translation?

Hidalgo: We kind of assume that there is a standard hour, a standard day, a standard month; a unit of measurement that everyone understands how long that is; and, in our storytelling, we say that all that measurement comes from Coruscant. So, not only is it the galactic capital, it's sort of the yardstick through which all time is measured in the galaxy.

^{Rebels Recon #2.09: Inside "The Future of the Force"}

Per the canon reference book Star Wars: Absolutely Everything You Need To Know, a standard day is 24 standard hours, and a standard year is 365 standard days:

It's unknown how, or if, this would have changed after the collapse of the Empire, when Coruscant ceased to be the capital of the galaxy; it seems unlikely that something like this would change, but you never know.