This is a sort of a technical post. Some have speculated on the time frame, so I am going to point out some possibilities.
The first stardate in "The Conscience of the King" is in Kirk's first log entry:
Captain's log, star date 2817.6. Starship Enterprise diverted from scheduled course. Purpose, to confirm discover by Doctor Thomas Leighton of an extraordinary new synthetic food which would totally end the threat of famine on Cygnia Minor, a nearby Earth colony.
Soon after, Kirk returns to the
Enterprise and asks the computer some questions:
COMPUTER: Working. Kodos the Executioner, summary. Governor of Tarsus Four twenty Earth years ago. Invoked martial law. Slaughtered fifty percent of population Earth colony, that planet. Burned body found when Earth forces arrived. No positive identification. Case closed. Detailed information follows. On stardate 2794.7,
Since the computer said 20 years, the famine on Tarsus Four should have been sometime between 20.0 and 20.999 years earlier. The computer didn't get to say what happened on stardate 2794.7. Possibly the Kodos case was closed on stardate 2794.7 which might have been the 20th anniversary of some important event on Tarsus Four.
But it is usually assumed that Kodos did something on Tarsus IV on stardate 2794.7, like declaring martial law, massacring colonists, etc. So if there are 20.0 to 21.0 years in a period of 22.9 stardate units (2817.6-2794.7), there would be 1.091 to 1.145 stardate units per year. Thus a thousand years would be 1,090.4761 to 1,145 Stardate units long.
Since there were over 4,000 stardate units during the five year mission, over 4,000 years would have passed on Earth and other planets while only 5 years passed on the
Enterprise! A good space opera story can be made where there is such a great time difference, but in
Star Trek time aboard a starship almost always passes at the same rate as time on a planet, or close enough that the audience never notices the difference.
Maybe there is no relation between stardates and the passage of time on planets. Or maybe there is a consistent ratio between stardates and time on planets, which requires new ideas.
In TNG a stardate unit was supposed to be one day long, thus making 365 or 366 stardate units in an Earth year according to the Julian and Gregorian calendars. And there were supposed to be 1,000 stardate units in a TNG year, so either a TNG year was about 2.7378 Earth years long and 1,000 Earth days long or there were about 2.7378 stardate units per Earth day. Or maybe there were no Earth units involved and a TNG year was 1,000 TNG days long.
If the TOS stardate system is similar, there might be between ten stardate units in an Earth day, or about 3,652.5 per Earth year, or ten Earth days per stardate units, or about 0.1 stardate units per day and about 36.525 stardate units per Earth year. Assuming that TOS years and days are Earth years and days, of course.
I once imagined that maybe whenever TOS stardate units reach 9999 they roll over or rest so that the next stardate is 0000. If someone was talking about a stardate 4444 during the same cycle it would be simply stardate 4444, but if talking about a stardate 4444 in a previous cycle it would be stardate 4444 in the 7th stardate cycle, for example, to identify it completely. And possibly
Star Trek characters sometimes identify the stardate cycle of a past stardate they mention, but the creators of the show leave out the mention of the cycle.
But I later decided that perhaps "real" stardates are at least 6 digits long before the c decimal point, and that
Star Trek characters always say the full six digits before the decimal point but the creators of TOS era episodes and movies only include the last four digits before the decimal point and the creators of TNG era episodes and movies only include the last five digits before the decimal point.
Assuming that the computer's stardate 2794.7 was actually stardate 112794.7 and there were 20.0 to 21.0 years between it and Stardate 112817.6. Then there would be only 22.9 stardate units between them and about 1.091 to 1.145 stardate units per year, which would be outside the range of 36.525 to 3,652.5 stardate units per year.
I find that there could be 10,000, 20,000, 30,000, 40,000, 50,000, 60,000, or 70,000 stardate units between XX2794.7 and XX2817.6 with the number of stardate units per year in the range of 36.525 to 3,652.5 stardate units per year. That does not narrow it down very much.
The stardates of TOS range from 1312.4 ("Where no Man Has Gone Before") to 5943.7 ("All Our Yesterdays") a difference of 4,631.3. If they all happen during the five year mission that should last between 4.0 and 6.0 years, that makes 771.883 to 1,157.825 stardate units per year., or more if the episodes don't fill up all the five year mission.
It is possible that "Where no Man Has Gone Before" happened before the start of the five year mission, making "Mudd's Women" stardate 1329.8 the earliest episode during the five year mission. Thus there would be 4,613.9 stardates in 4.0 to 6.0 years, or 768.983 to 1,079.225 stardate units per year.
The TAS epsiodes have stardates from 1254.2 ("The Magicks of Megas-Tu") to 7403.6 ("Bem"), or a difference of 6,149.4. If they all happen during the five year mission that should last between 4.0 and 6.0 years, that makes 1,1024.9 to 1537.35 stardate units per year., or more if the episodes don't fill up all the five year mission.
But what if there are one or more extra 10,000 stardate units during the five year mission. Putting in an extra 10,000 stardate units between two of the seasons, for example, would make 2,435.65 to 4,037.35 stardate units per year, that partially fits inside the range of 36.525 to 3,652.5 stardate units per year. Putting in an extra 20,000 stardate units between various season, for example, would make 4,102.316 to 6,537.35 stardate units per year, outside the range of 36.525 to 3,652.5 stardate units per year.
So going by the stardates in TOS, there should be 768.983 to 3,652.5 stardates per year. The movie TVH begins as Kirk makes a log:
Captain's log, stardate 8390. We are in the third month of our Vulcan exile. And it was Doctor McCoy with a fine sense of historical irony, who decided on a name for our captured Klingon vessel.
"In the third month" means between 2.0 and 3.0 months, or between 0.166 and 0.25 years, if Earth time is being used. The latest stardate in the previous movie, TSFS, is 8210.3, and some events happen after that and the beginning of hte Vulcan exile of Kirk & Co. Thus there might be 2.0 to 4.0 months, or 0.166 to 0.333 years, between stardates 8210.3 and 8390. if 179.7 stardate units equal 0.1666 to 0.3333 years, there are 539.153 to 1,078.243 stardate units per year.
Combining the 768.983 to 3,652.5 stars per year from analyzing the TOS episodes with the 539.153 to 1,078.243 star date units per year from the stardates between TSFS and TBVH produces a possible range of 768.983 to 1,078.243 stardates per year.
And thus we see there would be an extra 20,000 stardates between stardate 112794.7 during the famine on Tarsus IV and stardate 132817.6 during "Conscience of the King".
Then there would be 20,022.9 stardate units in 20.0 to 21.0 years, or 963.471 to 1,001.145 stardate units per year, inside the range of 36.525 to 3,652.5 stardate units per year.
So this pretty much establishes that there are between 963.471 and 1,011.145 stardate units per year, if the assumptions are correct, of course.
112794.7. A stardate during the events on Tarsus IV.
113000.0 Beginning of new set of 1,000 stardate units.
120000.0 Beginning of new set of 10,000 stardate units.
128786.6 Calculated earliest possible date for Kirk to become Enterprise captain.
130000.0 Beginning of new set of 10,000 stardate units.
130557.7 Calculated latest possible date for Kirk to become Enterprise captain.
131254.4 "Magicks of Megas-Tu"
131277.1 Possible stardate Kirk takes command of Enterprise - from tombstone.
131312.4 "Where No Man Has Gone Before". Last stardate 131313.8
McCoy becomes chief surgeon of Enterprise.
131329.8 "Mudd's Women".
131709.2 "Balance of Terror". Latest stardate 1709.6.
Romulans might sign Nimbus III Treaty after "Balance of Terror"
132817.6 "Conscience of the King".
133141.9 "Space Seed". Khan & followers left on Ceti Alpha soon afterward. Chekov might already be on Enterprise.
133198.4 "Errand of Mercy".Organian peace treaty signed soon after.
133468.1 "Who Mourns for Adonais?" Ensign Chekov, in Enterprise crew, is 22.
133478.2 "The Deadly Years" Kirk is 34.
133842.3 "Journey to Babel" Sarek is 102.437 Earth years old between stardates 133842.3 and 133842.4.
The Making of Star Trek says that Chekov is 22, thus making it less than one year after "Who Mourns for Adonais?" and that Sarek is 102, thus making it less than 0.563 years after "Journey to Babel". With between 963.471 and 1,011.145 stardate units per year, The Making of Star Trek must be before stardate 134489.34 and also before stardate 134411.67. The Making of Star Trek, Part II, Chapter 4, page 216 (1968 edition) says that 'Kirk has been in command of the Enterprise for more than four years". 4.0 to 5.0 years with 963.471 to 1,011.145 stardates per year equals 3,853.884 to 5055.725 stardates subtracted from stardate 133842.4 to 134411.67 gives stardates 128786.68 to 130557.79 as the range when Kirk may have taken command of the Enterprise.
135943.7 "All Our Yesterdays". Stardate 135943.9 is the latest stardate in TOS.
Kang says Klingons have kept the treaty for three years in "Day of the Dove". If that is 3.0 to 4.0 years with 963.471 to 1,011.145 stardate units per year after stardate 133198.4, the stardate of "Day of the Dove" should be between 136088.81 and 137242.98, giving "Day of the Dove" the latest stardate in TOS.
137403.6 "Bem". Stardate 137403.6 is the latest stardate in TAS.
137410.2 The first star date in TMP is 7410.2. That is only 6.6 stardate units after "Bem" and 1,466.3 after "All Our Yesterdays". Neither are sufficient.
140000.0 Beginning of new set of 10,000 stardate units.
144629.6 Kirk becomes Chief of Starfleet operations and logs his last star hour between stardates 144629.6 and 145242.4.
147410.2 Star Trek: The Motion Picture. (TMP) "Two and a half years" since Kirk became Chief of Starfleet Operations and since Kirk last logged a star hour. If two and a half years" is 2.25 to 2.75 years and there are between 963.471 and 1,011.145 stardate units per year, that was 2,167.809 to 2,780.648 stardates earlier.
Kirk and khan both say that WOK is 15 years since "Space Seed". If "fifteen years" is 14.0 to 17.0 years, with 963.471 to 1,011.145 stardate units per year, WOK should be sometime between stardates 146630.49 and 150331.36.
148130.4 Star Trek: The Wrath of khan (WOK). Only 720.2 Stardates, less than a year, after TMP.
148210.3 Star Trek III: The Search for Spock (TSFS) . Only 79.9 stardates since beginning of WOK.
148390.0 Star Trek IV: The Voyage Home (TVH). Only 179.7 stardates since beginning of TSFS.
148450.0 Star Trek V: The Final Frontier (TFF). Stardate is given between 8450.0 and 8459.9, 60 to 69.9 stardates since beginning of TVH.
In Star Trek V: The Final Frontier Caitlin Dar says Nimbus III Treaty signed 20 years before. If she loosely means between 19.0 and 22.0 years, and there are between 963.471 and 1,011.145 stardate units per year, there should be 18,305.949 to 22,245.19 stardate units in the interval. If the treaty was signed immediately after stardate 131709.6, TFF h should between 150015.54 and 153954.79. So either Dar is very loose with her numbers or she is using a different type of year.
150000.0 Beginning of new set of 10,000 stardate units.
158130.3. The possible fictional date of Saavik's Kubayashi Maru simulation in WOK, dated to a time when she might expect to be a starship captain.
In TUC, McCoy says he has been surgeon of the Enterprise for 27 years, probably meaning on and off. McCoy's twenty seven years may be loosely between 26.0 and 29.0 years. If there are between 963.471 and 1,011.145 stardate units per year, there should be 25,050.246 to 29,323.205 stardates in the interval. McCoy should become surgeon of the Enterprise between stardates 131313.8 and 131329.8, thus making the stardate of his statement between 156364.04 and 16065.0.
159521.6 Star Trek VI: The Undiscovered Country (TUC). Stardates 9521.6, 9522.6, and 9529.1. Kirk is due to retire and Enteprise-A be decommissioned in 3 months, probably between stardates 159762.46 and 159781.88.
160000.0 Beginning of new set of 10,000 stardate units.
168130.3. The possible fictional date of Saavik's Kubayashi Maru simulation in WOK, dated to a time when she might expect to be a starship captain.
In Generations a reporter says that the launch of Enterprise-B is the first time in 30 years there has been an Enterprise without Kirk as captain (ignoring the times that Willard Decker and Spock were captains of the Enterprise in between Kirk). The reporter might speak loosely of 30 years when the interval is somewhere between 29.0 and 32.0 years. With between 963.471 and 1,011.145 stardate units per year, there should be between 27,940.659 and 32,356.64 stardates in 29.0 to 32.0 years. If Kirk became captain of Enterprise sometime between stardates 128786.6 and 131312.4, the stardate of the launch of Enteprise-B in Generations would be between 156727.25 and 163669.04. That range includes the stardates of TUC, indicating that that the launch of the Enteprise-D could be shortly after Kirk retires 3 months after TUC.
So according to this chronology based on stardates, Kirk and the Enterprise apparently finished the five year mission and returned to the center of the Federation, where the Enterprise may have been a ceremonial ship with Kirk in command for several years. Then Kirk may have been promoted to commodore and put in charge of a large region of space. But Kirk may have put his office aboard the Enterprise, commanded by Commander Spock or by someone else, instead of on a starbase, and traveled around his sector a lot even if he no longer explored on the distant frontier. After some years the Enterprise may have been put in mothballs.
About 2.25 to 2.75 years before TMP. Kirk came to Earth and became Chief of Starfleet Operations. About 1.5 years before TMP, The Enterprise began to be rebuilt. Willard Decker became captain of the Enterprise.
Then came TMP.
WOK began 720.2 stardates, about 0.712 to 0.747 years, after TMP, not enough time for another five year mission. The Enterprsie became a training ship under Captain Spock almost immediately after TMP.
WOK, TSFS, TVH, and TFF apparently lasted for a total of a little over 320 stardate units or about 0.316 to 0.332 years.
At the end of TVH, Kirk was demoted from admiral to captain and given command of the Enterprise A. This was sometime between stardates 148390.0 and 148450.0. After TUC, Kirk probably ceased commanding the Enterprise A about stardates 159762.46 and 159781.88. If Kirk commanded the Enterprise-A for about 11,312.46 to 11,391.88 stardate units, with between 963.471 and 1,011.145 stardate units per year, Kirk would have commanded the Enterprise-A for 11.187 to 11.823 years.
Many fans would want Kirk to command the Enterprise for one or more five year missions between TMP and WOK. To arrange that WOK would have to begin on stardate 158130.4, 10,000 stardates later than given above. If "fifteen years" is 14.0 to 17.0 years, with 963.471 to 1,011.145 stardate units per year, or 13,488.594 to 17,189.465 stardates, the last time that Kirk and Khan saw each other would have been sometime between stardates 140940.94 and 144641.81, years after "Space Seed" and the five year mission. Thus Kirk would have checked up on Khan years after leaving him on Ceti Alpha V.
Putting WOK in stardate 158130.4 instead of 148130.4 would make it 10,720.2 stardates after TMP, or about 10.602 to 11.126 years. Kirk could have commanded the first Enterprise for most of that period before it became a training vessel under Captain Spock. Then Kirk could have commanded the Enterprise-A for 1,312.46 to 1,391.88 stardate units, or 1.297 to 1.444 years, giving him a possibly slightly longer total period in command of the Enterprises than in the previous chronology.
Another possibility would be for Kirk to take command of the Enteprise for another five year mission almost immediately after TMP. But almost immediately, the ship would enter a space/time warp and be flung into a distant place and time. After many years of adventures, the Enterprise could return though the space/time warp to almost the exact time and space it left from. The crew would be years older, the ship battered and fit only to be a training vessel. Then WOK could happen abut 0.75 years after TMP.