How Do Star Trek Stardates Actually Work?

There are few handier delivery mechanisms for "Star Trek" exposition than a Captain's log entry, crucial Starfleet records that mark time with "stardates" — an enigmatic calendar system integrating decimals into each date. Although based on a real-world astronomical dating system, the Starfleet version doesn't make a ton of sense because it was never meant to, which is why the "Star Trek" timeline can seem confusing the deeper you dig into it.

As outlined in a 1967 "Star Trek" writer and director's guide, "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." Still, understanding the Julian date system can be a good starting point for those who care to try.

Speaking with The Space Review in 2019, "Star Trek: The Original Series" technical advisor Kellam de Forest explained that the futuristic calendar system was inspired by the Julian day — the solar day measurement used in the 365-day Julian solar dating system that predated the Gregorian calendar. Because the Julian day system creates a continued count of dates from the beginning of the Julian period, the ease of calculation between two dates without breaks has made it the preferred calendar for many scientific applications, including astronomical software. Julian dates are calculated by adding the Julian day — that is, the solar day since the beginning of the Julian calendar — and then adding a decimal point to indicate the fraction of the day that has passed since noon in Universal Time Code (UTC). Although the Julian date calculates days running into the millions, only the final five digits are commonly used by astronomers — and just four are used in "Star Trek."

According to the "Star Trek" writer's guide, the Starfleet calendar system was invented to deemphasize the in-universe date. As the guide puts it, "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."

Speaking on the 1988 documentary "Inside Star Trek: The Real Story," de Forest emphasized that this almost wasn't the case since the original script contained dates from the Gregorian calendar. Upon reviewing the script, de Forest felt this didn't feel right for the future spacefaring society. As a solution, he pitched the Julian-inspired concept, which the tech advisor felt had a futuristic vibe thanks to its use of decimals.

While "Star Trek" creator Gene Roddenberry liked the concept as a jumping-off point, his version was always meant to be a little esoteric, as Samuel A. Peeples, who wrote the second pilot for "Star Trek: The Original Series," recounted in "Gene Roddenberry: The Myth and Man Behind Star Trek." According to Peeples, "We tried to set up a system that would be unidentifiable unless you knew how we did it." Conceptualizing the revised stardate system over drinks, Roddenberry and Peeples took into account the weirdness of space and relative time, ultimately concluding that any date-related continuity errors in "Star Trek" could be chalked up to these issues. Or as the "Star Trek" writer's guide put it, "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." In other words, don't think too hard about it.