III.8. REFERENCE POINTS: THE NEXT GENERATION
Throughout ST:TNG stardates have increased at approximately 1000 units per year. (In fact, during ST:TNG, the second digit of the stardate indicated the season.) From these facts, the Chronology has conjectured that ST:TNG stardates increase at exactly 1000 units per year. Numerous references within the series supports this conjecture. Of course, they support it because the shows were written with that system in mind. It would be difficult to contradict this.
However, there are a few inconsistencies in this respect within the series. In "Eye of the Beholder" (ST:TNG, SD 47622.1; incidentally, this is the second of (so far) three very near title clashes in Star Trek -- there was an animated Star Trek episode called "The Eye of the Beholder") an incident at Utopia Planitia is referred to both as stardate 40987 and as eight years ago; allowing for rounding, this gives a year length of between 704.4 and 954.4 units. In "The Pegasus" (ST:TNG, SD 47457.1), the disappearance of the Pegasus was stardate 36764 and twelve years ago; this gives a range of 807.8 to 974.4 units per year. In "Second Sight" (ST: DS9, 47329.4), the battle of Wolf 359 (SD approximately 44002) was exactly four years ago, giving a year length of 832 to 834.75 units.
There are some other references consistent with an 833 unit year, but most are not so clearly referring to Terran years. In any case, the vast majority of references support 1000 units per year, leaving these other references as isolated mistakes.
In "The Neutral Zone" (SD 41986.0), Data stated that the year was 2364. This almost solves the problem of year calculations. The only problem is that Data did not go on to say exactly what day of the year it was, so there is an uncertainty of one year when calculating dates from this.
III.9. FIFTH PERIOD OF STARDATES: THE NEXT GENERATION
Note that ST:TNG stardates have five digits before the decimal point, where ST:TOS stardates have four. This would seem to suggest a change of outlook on the part of the Federation, from short-term to long-term. This coincides with the change from stardate units being convenient fractions of Terran days to being a convenient fraction of a year. Also, the length of stardates in ST:TOS could allow for up to about 5.4 years before needing to be reset to zero, whereas the ST:TNG stardates only need to be reset once a century. (Presumably one often needed to specify which period of 5.4 years one meant by a particular stardate.)
The Chronology proceeds under the assumption that all first season stardates were in the year 2364, and then all second season in 2365, and so on. There isn't really any evidence to support this, but it makes things neat. The production crew have occasionally calculated exact dates on this basis. In order to keep things simple, it will be assumed that this is how the stardates actually work. This makes stardate 00000.0 midnight at the beginning of 2323-01-01.
Stardate 99999.9 should be about 50 minutes before midnight on 2422-12-31, after which the stardates get reset to zero again. However, it is not possible to state this as being exact, because not all centuries are the same length. Every fourth century contains 25 leap years; the rest have 24 each. The difference in the lengths of individual years creates a more immediate problem: the 1000s of units can't match up exactly with calendar years.
Obviously, one solution would be for the stardate rate to vary from year to year, making each year 1000 units whether it is 365 or 366 days long. This is not acceptable as a universal time system, however. The rate changing every fourth Terran year makes things difficult for the Vulcans, and the Andorains, and in fact almost every member of the Federation.
So the rate must make 1000 units fit a mean solar year of 365.2425 days exactly. (Actually that's not quite exact, but that is the exact mean length of a year by the Gregorian calendar. This is more appropriate, because the Gregorian calendar is being used to specify dates.) 400 years is exactly 146097 days, no matter which 400 years one counts. By a happy coincidence, this is exactly 20871 weeks. (This fact is of no practical use, except in the construction of perpetual calendars.)
For convenience, it can be conjectured that starships on extended voyages -- and maybe some civilians too -- use a standard year of length 365.2425 days. This doesn't mean they add on an extra 5.82 hours at the end of the year, but that they distribute it evenly throughout the year. This makes each day about 57.4 seconds longer than 24 hours. In fact, to make chronometers visually indistinguishable from those previously in use, the second would get longer.
This standard year is exactly 31556952 SI seconds long, but is internally divided into the usual 31536000 seconds. This makes the `chronological second' approximately 1.00066 SI seconds, and even Data would have difficulty distinguishing the two.
The two calendar styles could coexist quite easily, because they would rarely be more than a few hours different. In order for them to coexist over a long period of time, they must agree on what day of the week any particular date falls on. (A consequence of this is that existing perpetual calendars will still be applicable to the new calendar.) Where there would be a leap day in the old-style Gregorian calendar, there is merely a jump in the day of the week. For example, Wednesday 2396-02-28 would be followed by Friday 2396-03-01, missing out Thursday 2396-02-29 which would appear in the Gregorian calendar.
This new calendar will hereafter be called the "quad-cent calendar". It comes exactly into line with the old-style calendar every 400 years. Since the origin for ST:TNG stardates is 2323-01-01, that must be when the two calendars match up. (The next time will be 2723-01-01.) Hereafter, quad-cent calendar dates will be written like 2323*01*01, instead of 2323-01-01.
III.10. FOURTH PERIOD OF STARDATES: INTERMEDIATE, TCFS TO ST:TNG
SD 9521.5 corresponds to the date 2292-12-19. The digits run out and are reset to zero on 2295-08-03. This starts a special `issue' of stardates, whose sole purpose is to bridge the gap to 2323-01-01, when the new-style stardates take over. In this new issue, SD 5000.0 is 2322-12-20, almost exactly 30 years after STVI:TUC. This makes 2323-01-01 SD 5006.0. So stardate 5006.0 in that issue became stardate 00000.0, and the date, 2323-01-01, became 2323*01*01 for the purposes of stardates.
If Thanksgiving were twelve days later, these numbers would be unbelievably neat. So neat, in fact, that one might well reach the conclusion that this system was actually designed to work this way.