Stardate

A stardate is a fictional system of time measurement developed for the television and film series Star Trek. In the series, use of this date system is commonly heard at the beginning of a voice-over log entry, such as "Captain's log, stardate 41153.7. Our destination is planet Deneb IV …". While the general idea resembles the Julian date currently used by astronomers, writers and producers have selected numbers using different methods over the years, some more arbitrary than others. This makes it impossible to convert all stardates into equivalent calendar dates, especially since stardates were originally intended to disguise the precise era of Star Trek.

The following excerpt from Star Trek Guide (April 17, 1967, p. 25) instructs writers for the original Star Trek TV series on how to select stardates for their scripts:

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 "percentage point" mentioned was, in practice, a single decimal. The official timeline places the original series between the years 2265 and 2269, with the second pilot beginning on stardate 1312.4 and the last-produced episode on stardate 5928.5; however, this timeline is based on references in Star Trek: The Next Generation, and had not been developed during the production of the original series. Despite the guideline to "pick any combination", the list of episodes shows stardates increasing with time in general, albeit with many instances of a number being lower than in the preceding episode.

Stardates were revised from the above description for Star Trek: The Next Generation and all the subsequent shows and movies set in the same era. They were described as follows in Star Trek: The Next Generation Writer's/Director's Guide of March 23, 1987 (p. 13):

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