There are several problems that arise by keeping time across galactic distances, arising from relativity, FTL travel and lack of a unified referential.

How does the "Stardate" in Star Trek work then? Is it the same on Earth and Vulcan, for example? How does the federation keep its value the same across these distances?

  • Cross-site Related - scifi.stackexchange.com/questions/14130/how-do-stardates-work
    – Paulie_D
    Oct 18, 2016 at 19:28
  • There isn't a delay in "sub-space" communications, if I recall -- you can talk with another starship several light-minutes away and have no delays in your conversation. That could be used to explain it. (Though I bet it's just handwavium.) Oct 18, 2016 at 20:49
  • Subspace communication allows real time conversation at intergalactic distances. And warp and limited use of impulse prevent relativistic time differences.
    – cde
    Oct 18, 2016 at 21:26
  • 1
    @cde Interstellar, not intergalactic. A major plot point of Voyager was the inability to tell anybody back home what happened.
    – T.J.L.
    Oct 18, 2016 at 23:16
  • I'll comment instead of answer, since I can't be bothered check the techinical manual - but as I understand it there are relays all over the Federation which facilitate not only communications, but provide a constant "ping" which tells a starship what the common Federation date/time is. Each ship, colony, etc., regularly checks the ping to stay up to date. This means that a colony has two times - the local time, and the standard Federation time.
    – Tim
    Oct 19, 2016 at 2:05

3 Answers 3


According to the Original Series Writer's Guide:

We invented "Stardate" to avoid continually mentioning Star Trek's century (actually, about two hundred years from now), and getting into arguments about whether this or that would have developed by then. Pick any combination of four numbers plus a percentage point, use it as your story's stardate. For example, 1313.5 is twelve o'clock noon of one day and 1314.5 would be noon of the next day. Each percentage point is roughly equivalent to one-tenth of one day. The progression of stardates in your script should remain constant but don't worry about whether or not there is a progression from other scripts. Stardates are a mathematical formula which varies depending on location in the galaxy, velocity of travel, and other factors, can vary widely from episode to episode.

The Writer's Guide for The Next Generation stated:

A stardate is a five-digit number followed by a decimal point and one more digit. Example: "41254.7." The first two digits of the stardate are always "41." The 4 stands for 24th century, the 1 indicates first season. The additional three leading digits will progress unevenly during the course of the season from 000 to 999. The digit following the decimal point is generally regarded as a day counter.

Deep Space Nine began with 46379.1, corresponding to the sixth season of Star Trek:

Star Trek: Voyager began with stardate 48315.6 (2371), one season after TNG had finished its seventh and final season. As in TNG, the second digit would increase by one every season, while the initial two digits eventually rolled over from 49 to 50, despite the year 2373 still being in the 24th century.

Star Trek: Nemesis was set around stardate 56844.9, which is so far the highest stardate to have been mentioned in the Star Trek canon.

To answer the original question, there was never any rule devised by writers to explain what date was used, so one can only assume they used some sort of GMT (Greenwich Mean Time) across the galaxies, based on a focal point (which may or may not have been the Federation headquarters).


A universal standard of time is not possible.

The only reason a time standard on Earth works in our experience is because we are traveling at speeds too slow and distances too small for the lack of a "true time" to matter. But in the Star Trek universe, this is not the case. The "true time" differential would be significant. And, as a result, it would be impossible to implement.

Your question presupposes what scientists call the Netwon's Stage model of the universe. Essentially, that the universe exists as a static, passive stage upon which all the events of the universe play out with the backdrop of the synchronous passage of time. This model would be necessary in order to have a "consistent" stardate time standard.

However, Einsteins Special Theory of Relativity proved that Newton's Stage model is wrong across large distances — such as the galactic scale distances at play in Star Trek.

To picture how this works, one must first accept the principle that the speed of light is a universal constant. And it doesn't matter where an observer is located in the universe (or how "fast" that observer is traveling) the speed of light remains the same. In order for that to be true, then space and time must be "flexible" and allowed to distort relative to the perceptions of any given observer.

What that means for your question is that if two observers are traveling at different speeds, then the events of the universe play out at different times relative to each observer. In other words, there is no universally consistent concept of a "now" moment. All observers across the universe do not share the same "clock." And, therefore, there can be no universal time "clock" that all observers can agree to. Everyone's clock will be different depending on their history of relative speeds.

You can learn more by watching this video.

  • 2
    But there could still be a coordinated, universal time that everyone syncs with. If I'm traveling at 0.5c, my clock will just run slower, so I sync up once I decelerate. I could even estimate and update my "universal" time while traveling and just double check with the official servers once per day (or per week depending on how far I am from a rely station). Just like with GMT, we simply pick an arbitrary frame of reference (probably just Earth for lack of imagination) and sync to that. Apr 4, 2020 at 18:29
  • @jdk. I agree. This would be the most practical way of solving the problem. And similar to resetting your clock in the spring and fall for daylight savings time. However, the gain-an-hour-to-lose-an-hour (zero-sum) algorithm would be replaced by something non-zero sum.
    – Mowzer
    Apr 4, 2020 at 19:25
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    Seems to me this answer merely expands the question. Jan 2 at 1:38
  • This is all very scientific but the question asks about the show (where they do have it), not in reality.
    – Luciano
    May 21 at 8:44

The Federation keeps both Local and Universal times for it's operations.

In Deep Space 9, Bajor has 26 hours per sideral day, and maintains it on the station under it's administration. However starfleet maintains it's own clocks

TNG episode Cause and Effect, Federation maintains a network of Time/Space beacons with strictly isolated chronometers to keep time to incredibly precise degree. So precise it's presumably even ill affected temporal/time augmentation phenomena. Also in TNG episode "Timescape", Off the shelf federation subspace technology, allows for isolated pockets standardized time. enter image description here

As for casual measured time, whatever planetary time/clock system of the native species is widely adopted is what the civilian population goes by. It makes little sense to keep a universal time on planets with differing timescales. But it does make sense for a Naval/military service to maintain strict time to launch all subsequent deployments, experiments/science involving more than one starship across distances.

Effects of time dilation don't matter in Trek

  1. Sublight speeds are managed low (one-quarter or 0.25c as Full impulse) enough to avoid massive time discrepancies
  2. Laws of general/special relativity don't apply to subspace physics and warp.

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