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Last update: Feb 15 1997 Version 1.5
by Andrew Main <zefram@fysh.org>
1996-03-28, stardate [-31]7269.00



Originally, stardates were used so that Star Trek could be established as taking place a long way into the future without actually being pinned down to a particular time. The stardates were arbitrary, chosen without regard to consistency. The only thing that was consistent was that the stardates generally increased. However, because episodes got out of order in the production sequence, and were shown in a different order again, even this could not be relied upon from week to week.

Furthermore, even ignoring obvious verbal slips, the stardate ranges of episodes occasionally overlapped, and stardates sometimes even decreased within the confines of a single episode. When pressed for an explanation, Gene Roddenberry said:

This time system adjusts for shifts in relative time which occur due to the vessel's speed and space warp capability. It has little relationship to Earth's time as we know it. One hour aboard the U.S.S.Enterprise at different times may equal as little as three Earth hours. The stardates specified in the log entry must be computed against the speed of the vessel, the space warp, and its position within our galaxy, in order to give a meaningful reading.
Roddenberry went on to explain that stardates would be different in different parts of the galaxy at any one time. He admitted that he didn't really understand this, and would rather forget about the whole thing. And that was when there was only ST:TOS to consider.

Roddenberry's explanation does make some sense. It seems to suggest that stardates are completely subjective. This will be dealt with in the next section. Contradicting this, however, is the suggestion that position is relevant to the calculation. This part of his explanation, at least, must be discounted on the grounds of absurdity. His explanation is not canonical, so it may be treated like any other theory.


A common theory, picking up on part of Roddenberry's explanation, is that stardates are measured subjectively by each different starship. This means that relativistic time distortions, caused by travelling at impulse speeds, cause stardate rates to vary from an objective point of view.

Such a system would be useless across the Starfleet, because stardate X to the Enterprise would be stardate Y to the Potemkin, and stardate Z to the Sutherland. This situation is obviously not very helpful when arranging a rendezvous.

To be useful, stardates must be universal, and the computers will have to allow for time dilation. The computers available in the 20th century are capable of compensating for this effect, so it is certainly possible in the 23rd century. II.3. MISSION-BASED STARDATES

Another theory is that stardates refer only to the ship's current mission, but increase at an objectively constant rate. This is an improvement over the previous theory, because different ships' stardates would differ by constant values only. This theory has also been used to give some very plausible relative dates for ST:TOS.

However, it doesn't account for the Earthbound use of stardates, or the demonstrated universality of stardates in ST:TNG. Furthermore, if each ship has its own subjective epoch, it seems most odd that all stardates would increase at the same rate. The only type of stardates that would be of any use would be those referring to a single standard timebase (i.e. the Federation Timebase), and having the same origin for everyone.

The constraint of universality makes matters a little complicated, because it means that the rate of increase of stardates is not totally constant. For example, the duration of the ST:TNG series is confirmed within itself to have lasted about seven years, during which time the stardate has increased almost 7000 units. This is irreconcilable with the fact that SD 5943.7 to SD 7411.4 was more than two years (ST:TMP).


It has been suggested in numerous places that stardates are actually Julian dates, as used by 20th century astronomers, modulo 10000. This would make each stardate unit exactly 24 hours. This works well at some points in Trek history. Unfortunately, it makes the `five-year mission' some thirteen years long.


It has been suggested, in jest, that stardates are actually hexadecimal, and that it is merely coincidence that only decimal digits have been heard so far. This is worth mentioning, in order to point out that this FAQ proceeds on the basis that all stardates are specified in decimal.

It is interesting to note, however, that the distribution of digits is far from uniform. A canonical stardate ending in ".8" is a real rarity, though not totally unknown. The distribution of single decimal digit fractional parts, according to the most up-to-date episode list I can get at the time of writing, is thus:

      Digit  Occurrences  Proportion
          0            8       2.34%
          1           54      15.79%
          2           73      21.34%
          3           58      16.96%
          4           48      14.04%
          5           34       9.94%
          6           17       4.97%
          7           28       8.19%
          8            6       1.75%
          9           16       4.68%
      Total          342     100.00%

It used to be widely stated that the first digit of ST:TNG stardates was 4 because it was set in the 24th century. Obviously, this idea can have no place in a proper theory, because it would make each century ten years long. It is, however, the way this digit was decided initially for ST:TNG. The Voyager episode "Basics, Part II" finally canonically laid this bit of bunkum to rest, when it announced a stardate of 50032.7, while remaining firmly in the 24th century (2373 to be precise).


Many people have noted that between ST:TOS and ST:TNG, as well as the stardate system being revised, the warp factor scale changed. The warp scale had previously had no upper bound on warp factors, but the new scale has a maximum of warp 10, which is defined as infinite speed. (See the Warp Speeds FAQ for futher information.) It has been suggested that both changes happened a the same time, possibly as the result of the same new knowledge about the nature of time, warp drive, and the interaction of the two.

However, it actually appears that the warp scale changed sometime during the classic film series, well before TNG stardates were used. Consequently the two changes can not have occurred at the same time.

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