(written from a Production point of view)
The Enterprise is hurled back in time to the year 1969, where the US Air Force sights it as a UFO. The crew must find a way to erase evidence of their visit before trying to get back to their future home.
At an Air Force base in 1969, an airman by the name of Webb detects something on his RADAR. At first, his commanding officer believes it to be an enemy aircraft. The signal is over Offutt AFB near Omaha, Nebraska, but the strange part is that it just appeared. It is as if it simply dropped out of the sky.
Interested by the strange appearance of this aircraft, Webb's commanding officer orders someone to go up there and take a look. He believes they may have a real UFO on their hands. Outside, a military F-104 fighter is launched. In the sky, the starship USS Enterprise is gliding through the clouds.
- "Captain's Log, Stardate 3113.2, subjective time: We were en route to Starbase 9 for resupply when a black star of high gravitational attraction began to drag us toward it. It required all warp power in reverse to pull us away from the star but like snapping a rubber band, the breakaway sent us plunging through space, out of control to stop here, wherever we are."
Except for secondary systems, everything is operational and they are heading on impulse power. Chief Engineer Montgomery Scott brings on auxiliary power from engineering, and Captain James T. Kirk asks to report damage and casualties to First Officer Spock. Kirk asks Uhura to contact Starfleet Control, to advise them of the black star's close proximity to Starbase 9. Casualty reports show nothing more than minor injuries. Scott reports that warp engines are offline, and he is holding them at impulse in orbit over Earth. The breakaway from the star threw the ship to Earth. They are, however, in a low orbit, and Kirk orders Sulu to use impulse to rise to a higher orbit. Sulu reports that the helm is answering but is a little sluggish.
Uhura reports that there is no response on any standard Starfleet channels; however, she is getting something on another frequency. A radio broadcast states that the first manned moon shot is to take place on Wednesday. Kirk recalls that the first manned moon shot took place in the late 1960s. Spock concludes that the Enterprise is also in the 1960s, having been thrown backward in time by the black star's whiplash.
Uhura reports that she is picking up ground-to-air transmissions. A military craft is approaching the Enterprise, fast. The craft, designated Bluejay 4, is gaining on the UFO (Enterprise). Kirk orders Sulu to gain altitude faster. Bluejay 4 states that the UFO is climbing, and he will go in closer. As he raises altitude, Blackjack (the Omaha base) states that Bluejay 4 should be close enough for visual contact. Bluejay 4 spots the Enterprise, which is climbing in the sky, amazed at its size. He starts to describe the UFO, and tries to determine what purpose the cylindrical projections might serve. Blackjack states that backup forces should rendezvous in about two minutes, but Bluejay 4 remarks that the UFO is not going to be there by then. Blackjack gives order to shoot down the UFO, or at least disable it. Spock concludes that the aircraft may be armed with nuclear warheads, which in the Enterprise's severe condition, could possibly cause serious damage to the hull. Kirk orders Scott to lock on with a tractor beam, but Spock advises against it. Scott locks on, regardless, and the aircraft begins to break up. Kirk orders the pilot beamed aboard. He goes to the transporter room to meet the pilot, and welcomes him aboard. The pilot is surprised to learn that Kirk speaks English, and gives his identification as Captain John Christopher of the United States Air Force, service number 4857932. Kirk remarks that the captain is among friends, and introduces himself. Captain Christopher asks Kirk who they are, and what happened. Kirk states that all will be revealed in good time, but Captain Christopher is understandably impatient.
On the bridge, Spock reports that the aircraft has broken up. They turn off the tractor beam, and Kirk takes Christopher to the bridge. Christopher seems surprised to see a woman in the halls. Christopher admires the size and complexity of the ship, and as Kirk explains that the ship is one of twelve like it in service of the United Earth Space Probe Agency. He freely admits that he is from the future. On the bridge, Christopher (after joking about "little green men") is taken aback by Spock's skin tone. As Kirk allows Christopher to look around the bridge, Spock expresses his concerns about their guest to Kirk privately.
As Christopher looks around, Spock reports that most main systems have been restored, including the main deflector, which will prevent them from being detected again. Spock also expresses concern for Christopher's presence. He states that Christopher cannot return to Earth, as this could alter the course of history. Kirk states that this is an annoying conclusion, but accepts the truth. He asks Spock to get Captain Christopher some more comfortable clothes, and to bring Christopher to his ready room.
In his quarters, Kirk makes a computer recording.
- "Captains log, supplemental. Engineering officer Scott reports warp engines damaged, but can be made operational and re-energized."
Kirk also gets annoyed by the computer's frequent references to him as "dear". Kirk asks Spock to fix the computer's affection. Spock explains that the computer had recently been overhauled on the female-dominated planet Cygnet XIV (who thought the computer needed a personality). Christopher finds the computer system amusing, and would love to see how the dilemma works out. It is at this point, that Kirk breaks the news to Christopher that he cannot be sent back with information he now knows from the future. Christopher asks about his disappearance, but Spock says that Captain Christopher made no relevant contribution to history. Christopher says that this is an outrage, having a wife and children back on Earth, something which seems to catch Spock's attention. He says it is his duty to report what he has seen, but Kirk says that the risk is impossible. Kirk offers his heartfelt apology.
Scott calls to tell Kirk that the engines will be operational in about four hours, but they have nowhere to go in this time. Kirk understands. Christopher finds some comfort in the fact that Kirk and his crew cannot go home themselves.
- "Captain's log, Stardate 3113.7, subjective time: Our engines are being repaired, but we are still locked in time, and we have aboard a passenger whom we do not want, and we cannot return."
Finally getting fed up with the computer, Kirk asks it to record that it either be repaired, or scrapped, which seems to take care of the computer problem. Spock calls Kirk, stating that he has new information regarding Christopher. Kirk orders Spock to report to his quarters, and that he will call Captain Christopher. However, Christopher does not respond to Kirk's hails. Kirk orders a security alert, noting that Captain Christopher is not in his assigned quarters. Kirk hypothesizes that he may be trying to escape, and goes to find him.
Christopher is indeed trying to escape, but runs into security officer Bobby on his way to the transporter room. He takes out the security officer, and acquires his phaser. Entering the transporter room and pointing his phaser at Kyle, Christopher tells Kyle that he wants to be transported to the surface immediately, but before he can complete his escape, Kirk comes, disarms Christopher, and knocks him out. In sickbay, Dr. McCoy reports that the injuries are superficial, and Kirk sympathizes about Christopher's want to escape. It is at this time that Dr. McCoy says that they too are just as stuck as Christopher. They can't beam down the entire crew, as it would be too great a disturbance in the timeline. Kirk however, says that Enterprise is not at that situation yet, but even if they do get back to their time, Christopher would be useless, archaic. McCoy says that he may be able to be retrained, but Christopher says that he cannot forget his family. He remarks that he is feeling fine, and Spock comes to sickbay. They cannot keep Christopher aboard, because his son, Colonel Shaun Geoffrey Christopher, did make an historic contribution, heading the first Earth-Saturn Mission. Christopher remarks that he has no son, to which McCoy responds, "yet". Kirk realizes that they must find a way to return Captain Christopher, and Christopher himself muses of the fact that he someday will have a son.
In orbit of Earth, Spock states that the biggest problem they must deal with is that Christopher's plane wreckage landed in open land ("an open section of Southern Nebraska"), so search parties will know that he wasn't on the plane. Also, Captain Christopher informs them that his radio conversation was recorded, and that his wing cameras were recording the Enterprise. Kirk remarks that these UFO sightings were usually taken for explainable things, but Spock remarks that their tractor beam destroyed the plane, making them nothing else but a genuine UFO. Kirk then asks about returning them to their own time. Spock has a theory, albeit complicated, which may work. Kirk then makes a plan; they need to destroy the hard evidence of their presence, so that if Christopher reports, there is nothing to support his claims, and he simply joins the ranks of one of thousands who has seen a UFO. Christopher then offers his help, and he sketches out a layout of the base on a PADD.
At the base, Kirk and Sulu beam down, Sulu with a bag for the tapes. They are a bit disoriented at first, but soon find the correct room. They force the door open with little difficulty using their technology. Upon entry, Kirk starts to look for what they need, and soon finds the audio tapes. On the Enterprise in the transporter room, Dr. McCoy is getting nervous, but Spock reassures him, noting that stealth missions are much more complicated than others. McCoy starts to get annoyed, and asks Spock whether he should be working on his time warp calculations, to which he calmly responds, "I am." Back at the base, Kirk and Sulu finish getting the tapes, when a Security Police staff sergeant enters. He orders them to give him the belts and the bag, with the tapes inside. On the ship, Spock now agrees with McCoy and starts to think it has been too long, so he calls the captain. The security officer opens one of the communicators, transmitting an emergency signal. Spock orders an immediate beam-up, only to find that they beamed up the wrong man. They now have two undesired passengers aboard, and the sergeant is frozen out of both surprise and fear. Kirk calls Spock, reporting that they now clearly have another problem.
- "Captain's log, Stardate 3113.9, subjective time: First Officer Spock recording. Due to an unfortunate accident, we have taken aboard another unwanted passenger."
Kirk informs Enterprise about their "surprise package", and asks them to keep him in the transporter room. After finishing up in the audio tape section, both Kirk and Sulu go to retrieve the video tapes of Enterprise. They find them in the dark room, but set off a silent alarm. They finish collecting the video, but after a small brawl with some security officers, Kirk gets caught. Sulu however, seems to have disappeared. He managed to beam up, with the tapes, and Kirk calmly explains to the curious guard that it was only he who was prowling about.
On the Enterprise, Scott reports that warp engines are ready for re-firing. Spock orders them to be, so that they can have full power. Down on the surface, Kirk is being interrogated by the guards who caught him. Kirk jokingly references that he got in to the base by popping in out of thin air. Lieutenant Colonel Fellini picks up Kirk's phaser, mistaking it for a radio transmitter. Then he wonders about Kirk's uniform and he starts to list Kirk's offenses, threatening to lock him up for 200 years. Kirk ruefully comments that that ought to be just about right (to return him to his own era).
Back in orbit, Spock and Christopher hypothesize in the Enterprise's briefing room as to the captain's most probable situation, as they are planning a rescue operation. However, Christopher insists on coming down with them, to which Spock reluctantly agrees. He issues phasers only to himself and Sulu, set on maximum stun. They beam down, as the security policeman who beamed up earlier is amazed. Kyle offers the guard some chicken soup from a food synthesizer to satisfy his hunger, which only amazes him more. On the surface, Spock takes out the two guards holding Kirk, and frees him. However, while Kirk and Sulu talk, Christopher gets one of the security guard's guns. He holds it to Kirk, refusing to be beamed back up.
Kirk tries to talk Christopher out of it, but he doesn't listen. He asks Spock to come out of Colonel Fellini's office, but as he moves towards Kirk, Spock comes up from behind, and administers a nerve pinch. He had suspected Christopher's actions, and had beamed into location for incapacitating Christopher. Sulu then beams up all four officers.
- "Captain's log, Stardate 3114.1, subjective time: We must make an attempt to break free of this time or we and our reluctant passengers will remain its prisoners. All we have is a theory and a few facts."
Mr. Spock says that the best possible course of advantage is to use a slingshot effect like the one they used to arrive in the first place. Theoretically, the whiplash from the sun's gravity would send them into another time warp. At this point, Christopher asks what they will be doing about him and the guard. Spock states that for a moment, they will go into the relative past, and transport both the captain and the guard to points before they were beamed up. The events, though still in their minds, will not have occurred, so there would be nothing for them to report. Scott now brings up one problem. The Enterprise may not have enough braking control to stop in their own time. They may overshoot their century, or be torn apart. In other words, it won't be an easy ride.
Everyone assumes stations, as the Enterprise prepares for the time-warp. They leave Earth, and head towards the sun at warp factor 3. Christopher, at this point, tells Kirk how he always wanted to make it into space, and Kirk tells him that he made it farther than anyone in his century. As Enterprise heads towards the sun, their warp factor increases, and the chronometers have started to move backwards. Christopher goes to put on his flight gear, and reports to the transporter room. As they approach the breakaway point, Sulu engages engines, and the ship is severely thrown. All power is just barely enough, but they do break free of the pull. As they head away from the sun, they gain speed, and the chronometers begin to move forward. Christopher prepares to beam back to Earth, and thanks Kirk for the look ahead. As they approach Earth, they energize, beaming Christopher back into the plane cockpit. However, there is no longer any Enterprise in the sky. Christopher reports to Black Jack, marking down Enterprise as another UFO. They then beam down the guard, but he too finds no unusual activity at the base.
As they approach their century, they have to begin braking, despite some risks. Kirk, being annoyed by Spock's countdown, asks him to just never mind. They begin braking, but the ship is thrown violently. Scott reports from engineering that the engines are buckling, but they manage to make a safe and complete stop. They hear the friendly voice of Starfleet control, and Kirk reports that the Enterprise is home.
"I never have believed in little green men."
"Neither have I."
- - Christopher and Spock, in their first encounter
"Don't touch anything, but I think you'll find it interesting."
"Interesting is a word and a half for it, captain."
- - Kirk and Christopher, on the bridge
"Maybe I can't go home, but neither can you. You're as much a prisoner in time as I am."
- - Christopher to Kirk, in the captain's quarters
"Now you're sounding like Spock."
"If you're going to get nasty, I'm going to leave."
- - Kirk and McCoy, on retraining and re-educating Christopher for the future
"I made an error in my computations."
"Oh? This could be an historic occasion."
- - Spock and McCoy, in sickbay
"Wait a minute. I don't have a son."
"You mean yet."
- - Christopher and McCoy
"It is a fact, Doctor, that prowling by stealth is more time-consuming than a direct approach."
- - Spock to McCoy, in the transporter room
"How did you get in?"
"I popped in out of thin air."
- - Fellini and Kirk, during Kirk's interrogation
"I am going to lock you up for two hundred years."
"That ought to be just about right."
- - Fellini and Kirk
"Blast your theories and observations, Mr. Spock! What about Jim? He's down there alone, probably under arrest! He doesn't have a communicator and we can't locate him or beam him back aboard without one!"
"I am aware of that, doctor."
- - McCoy and Spock, about Kirk
"Anyway we do it, it's a mighty rough ride."
- - Scott, on the slingshot effect
- This episode was originally going to be the second part of a two part story that would have begun in "The Naked Time". In an earlier draft of the script, when Kirk ordered a hyperbolic course, he wanted the direction to be "Doesn't matter... the way we came... toward Earth." 
- The episode originated from a one-page story synopsis associate producer Robert Justman submitted to Gene Roddenberry on 12 April 1966, for possible consideration. Although almost beat for beat, Justman's proposed story is the same as this episode, Roddenberry never acknowledged Justman as the source or paid any royalties to him for the idea. (Inside Star Trek: The Real Story, pp. 133-137)
- The music played as Christopher observes the ears on Spock, heard in its entirety in "The City on the Edge of Forever", was written by composer Joseph Mullendore during his scoring for "The Conscience of the King", but it went unused at that time. It is an uptempo version of the closing theme for the show. Mullendore had also arranged the "lounge" version of the theme for the same episode, also heard in "Court Martial".
- Kirk's assertion that there are only 12 starships like the Enterprise in the fleet is contradicted in The Making of Star Trek by Gene Roddenberry and Stephen E. Whitfield, which lists the names of fourteen starships.
- Kirk tells Captain Christopher that the Enterprise operates under the authority of the "United Earth Space Probe Agency," which Kirk describes as a "combined service" when Christopher presumes that the Enterprise is operated by the navy. Along with Kirk's log entry reference to "UESPA" in "Charlie X", this is the only time in the original series that this authority is mentioned. In the Star Trek Concordance, author Bjo Trimble suggests that it is a fictional name, designed to keep Capt. Christopher in the dark about the true nature of the Federation. The name would be established canonically as being the agency under whose authority the United Earth Starfleet operated under in Star Trek: Enterprise.
- This episode is the first of two episodes to have a food synthesizer in the transporter room. According to D.C. Fontana, budgetary restrictions precluded taking the security police sergeant to a dining facility or having another actor in the scene bring him food, so Kyle was employed to provide the sergeant's chicken soup from the dispenser. (The World of Star Trek, 3rd ed., p. 40)
- This episode is unique in that it is the only episode to end on a close up of George Takei, who does not have the final line in the episode.
- This episode (or more accurately its stardate of 3113) was used as the basis for the "origin" of material that was published as the Star Fleet Technical Manual. The first pages of this manual explain how this occurred.
- Footage of the Earth (going closer and further, inside the atmosphere) on the Enterprise viewscreen is reused from "Miri".
Props and CostumesEdit
- Matt Jefferies designed the trophy with the soaring jet aircraft, seen in the case on the air base.(citation needed • edit)
- The small scanning device that Kirk uses to unlock the Omaha base computer-room door appears to be the same one used by Scott and Joe Tormolen in "The Naked Time", and by Richard Daystrom in "The Ultimate Computer".
- Actor Roger Perry liked his Starfleet uniform so much, he asked DeForest Kelley if he could take the shirt home. Kelley replied, "Well, they frown upon that. But you could possibly just stick it into your bag, and nobody's going to say anything." Perry decided not to do that, but after seeing the eventual success and legacy of Star Trek, he regretted he didn't take the shirt home. (These Are the Voyages: TOS Season One, p. 428)
- This is the first episode where we see the Enterprise during its Five-year mission visiting Earth.
- The events of this episode, which take place in 1969, occurred over a year before those of "Assignment: Earth", which take place in 1968.
- This is the last episode in which Spock's rank is stated as lieutenant commander.
- This episode establishes the presence of a quartermaster on board the Enterprise. Kirk said to Spock (referring to Captain Christopher), "Why don't you have the quartermaster issue him something more suitable?"
- One-page synopsis by Robert Justman: 12 April 1966
- Story outline by D.C. Fontana: 3 October 1966
- Revised story outline: 13 October 1966
- First draft teleplay by Fontana: 31 October 1966
- Second draft teleplay: 9 November 1966
- Final draft teleplay by Gene L. Coon: 21 November 1966
- Additional revisions: 22 November 1966, 1 December 1966
- Filmed: 28 November 1966 – 5 December 1966
- Original airdate: 26 January 1967
- Rerun airdate: 13 July 1967
- First UK airdate: 16 August 1969
The remastered version of "Tomorrow is Yesterday" aired in many North American markets during the weekend of 5 May 2007. The episode was heavy in new effects, with revamped CG shots of Earth from orbit – based on NASA space shuttle photographs – as well as new CGI shots of Captain Christopher's jet fighter, the Enterprise falling into Earth's atmosphere and an all-new sequence depicting the slingshot around the sun. 
Video and DVD releasesEdit
- Original US Betamax release: 1985
- UK VHS release (two-episode tapes, CIC Video): Volume 12, catalog number VHR 2305, release date unknown
- US VHS release: 15 April 1994
- UK re-release (three-episode tapes, CIC Video): Volume 1.8, 2 December 1996
- Original US DVD release (single-disc): Volume 11, 23 May 2000
- As part of the TOS Season 1 DVD collection
- As part of the Star Trek: Fan Collective - Time Travel DVD collection
- As part of the TOS Season 1 HD DVD collection
- As part of the TOS Season 1 Blu-ray collection
Links and referencesEdit
- DeForest Kelley as Dr. McCoy
- Hal Lynch as the Air Police sergeant
- Richard Merrifield as Webb (credited as "Technician")
- John Winston as Kyle (credited as "Transporter Chief")
- James Doohan as Scott
- George Takei as Sulu
- Nichelle Nichols as Uhura
- Mark Dempsey as the Air Force captain
- Jim Spencer as the Air policeman
- Sherri Townsend as a crew woman
- Majel Barrett as the computer voice
- William Blackburn as Hadley
- Frank da Vinci as Brent
- Eddie Paskey as Leslie
- Unknown actors as
1954; 1968; 1969; 2217; 498th Air Base; ADC Control; Air Defense Command; Alpha Centauri; Apollo 11; astronaut; B-52 Stratofortress; black hole; blackjack; blip; Bluejay 4; Cape Kennedy; chicken soup; Christopher, Shaun Geoffrey; cloud cover; Cygnet XIV; drawing; Earth; Earth-Saturn probe; F-104 Starfighter; horse; logic; Luna; March, M.; Mercury; mirage; NASA; Nebraska; nuclear warhead; Omaha; Pluto; quartermaster; RADAR; rubber band; Saturn; slingshot effect; Sol; Starbase 9; Starfleet Control; staff sergeant; Statistical Services Division; sun dog; time zone; tractor beam; truck; United Earth Space Probe Agency; UFO; USAF; US Navy; Vulcan neck pinch; weather balloon
- "Tomorrow is Yesterday" at StarTrek.com, the official Star Trek website
- "Tomorrow is Yesterday" at Memory Beta, the wiki for licensed Star Trek works
- "Tomorrow is Yesterday" at Wikipedia
- "Tomorrow is Yesterday" at MissionLogPodcast.com, a Roddenberry Star Trek podcast
| Previous episode produced:|
"The Alternative Factor"
| Star Trek: The Original Series|
| Next episode produced:|
"The Return of the Archons"
| Previous episode aired:|
| Next episode aired:|
| Previous remastered episode aired:|
"A Piece of the Action"
|TOS Remastered|| Next remastered episode aired:|
"Errand of Mercy"