As the first Star Trek episode where the Enterprise visits the 20th century (and, in some ways, a template for Star Trek IV: The Voyage Home), this is one of Star Trek's more popular episodes. Unfortunately, the premise is stronger than the overall story, with missed opportunities and a confusing ending leaving plenty of room for future episodes to do better (which they do).
The center of the drama is Captain Christopher (Roger Perry) of the . Air Force, a 1960s man who accidentally ends up on the Enterprise. He wants to go home to his wife and kids, but Kirk is wary about letting him return to Earth with knowledge of the future. It's a killer premise from associate producer Bob Justman, theoretically giving fans the next best thing to visiting the Enterprise themselves. But Christopher proves to be a poor audience surrogate, reacting with detached amusement and seeming more interested in women than the wonders of the future. (Most people today would probably identify more with Sisko's reaction in "Trials and Tribulations", where he responds to a trip to the Enterprise like a kid in a candy store). Nonetheless, as the episode progresses, it becomes a delight to see Kirk, Spock and company visit 1960s Earth and attempt to cover their tracks. Seeing these characters deal with 20th century people and technology is a fun juxtaposition, one that never gets old. (Shatner has a great moment where he taps a bulletin board, amused by the archaic use of paper). And as Kirk and company keep digging a deeper hole for themselves, the tension becomes almost tangible, with so many problems it seems impossible to solve them all. Fortunately for Kirk, the scriptwriter seems to think that since this is the first time travel episode (aside from "The Naked Time"), she's able to make up whatever rules she wants to conveniently tie up all the issues at once. The sad truth, however, is that her logic, filled with temporal paradoxes, makes no sense even in a fictional universe, and the ending seems a cheat as a result.
Interestingly, while we now look at the episode as taking place in the past, when it first aired it represented the future (hence the title, which lost its meaning after the 1960s). With three men about to go the Moon for the first time, it either takes place in 1968 (when Apollo 8 orbited the Moon) or 1969 (when Apollo 11 landed on the Moon). Either way, Kirk's assertion that this happened in the late 1960s was a bold but savvy prognostication by the . Fontana when she wrote the line in 1966. At the time, the Apollo program was still in its infancy and had yet to attempt a manned launch. (Put it this way: if you think of the Earth as a basketball, before the Apollo Moon missions, mankind had never been more than an inch from the surface. To get to the Moon, about the size of a softball, it was a distance of 17 In fact, even in 1967 when the "Tomorrow is Yesterday" aired, it was still uncertain that the Americans would beat the Russians to the Moon as the episode indicates. The Russians weren't capable of landing on it, because that took more complex software than they had. But using the Moon's gravity to slingshot a rocket around it is more about hardware, an area they excelled at. Fearing the Russians would do just such and declare victory in the space race was one of the reasons NASA rushed Apollo 8, going to the Moon before the Lunar Module was even ready to be tested. (Even so, NASA had to sweat out the preceding months, because Russia's geographical location gave it an earlier window to launch spacecraft, and the . never announced when its launches would But unknown to NASA and the American public (including Fontana), the Russians were running into some problems with their space agency in the mid 1960s and had, without announcing it, given up by 1967.
Remastered: While an Earth-based episode wouldn't seem a forum for a lot of fancy effects, the story actually requires quite a number; and getting the Earth right is harder than any other planet, because we know it so well. Truth be told, the original effects are pretty bad, using the same sorry Earth from Miri and having a cartoonish Enterprise in the Earth's atmosphere. (They artfully avoid showing the Sun, having the Enterprise get caught in place by its gravitational pull before breaking free). The upgrades are fabulous, with an Earth that looks like the real thing (because it is), gorgeous shots of the Enterprise, a new jet for Captain Christopher (with an improved cockpit view), a new chronometer (to match the other remastered episodes), and a slingshot around the sun (with Mercury making a cameo) just as the ship does in Star Trek IV. (The Sun, it should be mentioned, is depicted as a yellow fireball, just as it's commonly thought to be in the popular culture. But actually, scientists finally learned in the 20th century that it only appears that way because of our atmosphere and that in space it can be seen as the plain white ball it is. CBS Digital probably took artistic license to make it recognizable and keep it consistent with Star Trek IV).