Vulcan Calendar

A Brief Summary

Day: 26 hours, 43 minutes and 7 seconds; 1.113 Earth days.
Year: 0.584 Earth years; 213.44 Earth days; 191.722 Vulcan days.
r’tas: 2 Vulcan years; 383.444 Vulcan days; 1.169 Earth years; 426.88 Earth days.
Month Vulcan Days Long
Z’at 32
D’ruh 32
K’riBrax 32
re’T’Khutai 32
T’keKhuti 32
Khuti 32
ta’Krat 31 (32 in “long” r’tas)
K’ri’lior 32
et’khior 32
T’lakht 32
T’ke’Tas 32
Tasmeen 32

There are four “long” r’tas in every nine r’tas; the second, fourth, sixth and eighth years in each cycle.

What Do We Know?

Vulcans live their lives by a seven-year mating cycle. Over the years, we’ve heard a lot about it. So much, in fact, that I’ve set up a separate page Pon farr to explain why I’ve used it to inform rather than dictate my calendar decisions.

Beyond the mating cycle, we don’t know an awful lot. Although I’ve now decided it’s “apocryphal,” there is a specific Vulcan date in TAS “Yesteryear.” It seems over-keen to ignore it, since it’s the only one there is. Spock is saved by his “cousin” on 20th Tasmeen, 8877. Although it’s often stated to be 30 Vulcan years ago, a close study of the dialogue permits some hair-splitting. It’s definitely 30 years ago, but that appears to be a reference to Earth years. All we know in Vulcan terms is that it’s 25 to 30 Vulcan years before the story.

“Star Trek Beyond” established that Spock was born on S.D. 2230.06. This matches the date in a deleted scene from the 2009 film.


There’s a lot of deliberately confusing information about Mister Tuvok on “Star Trek: Voyager”. Taking things in chronological order:

Tuvok was 29 years old at the time of “Star Trek VI: The Undiscovered Country”, according to VOY “Flashback.” My calculations place the film in 2293, putting his birth sometime in 2263 or 2264. Unhelpfully, Tuvok gives his date of birth in VOY “Unimatrix Zero, Part I” as S.D. 38774. According to VOY “Flashback,” the assignment on Excelsior was Tuvok’s first deep-space assignment, and he resigned from Starfleet shortly after the events of “Star Trek VI: The Undiscovered Country”. He explains that he resigned because he disagreed with Spock about an alliance with the Klingons, in VOY “Alliances”.

Again according to VOY “Flashback,” Tuvok then returned to Vulcan to devote himself to Vulcan mental disciplines. Six years into his meditations, Tuvok was overwhelmed by pon farr, and married T’Pel. Tom Paris’s researches in VOY “Alice” places this event in 2304, and also says that Tuvok’s daughter was born after his eleventh pon farr. It’s stated several times around the internet that Tuvok’s only daughter is his youngest child. I haven’t been able to confirm that. Tuvok’s listing of his children in VOY “Elogium” as “three sons and a daughter” doesn’t establish the order of birth, to my mind. That still places the start of Tuvok’s meditations around 2298, though. VOY “Ex Post Facto” establishes that Tuvok has only married once, and that it’s been for 67 years at the time of the story. I have set VOY “Ex Post Facto” in January 2372, placing Tuvok’s marriage in 2304 or 2305. VOY “Fury” establishes that Tuvok’s daughter is old enough to have undergone kolinahr. His daughter’s name is given as Asil in VOY “Unimatrix Zero.”

After over fifty years, Tuvok rejoined Starfleet. VOY “Alice” implies that it was only very slightly over fifty years, since Paris says that he’s been in Starfleet for 33 years. I’ve set the story in September 2376, so that would be 2343. Even if Paris is hopelessly wrong, Tuvok has to have been an Academy instructor for 16 years before “Star Trek: Voyager”. That means he cannot have re-joined any later than 2355.

The next date is impossible to fix with any certainty, although it may be the 2240s. Anyway, VOY “Hunters” establishes that Tuvok’s “first” (eldest?) son Sek had his first pon farr sometime between mid-2371 and December 2374. If he’s around 30 at the time, then Sek would be born around 2341 to 2344, although it could be that he’s older than that, or maybe even younger.

Tuvok says he has known Janeway for “approximately 20 years” in VOY “Fury”, which I have in March 2377. This suggests that they first met in the late 2050s.

In VOY “Revulsion” Tuvok is promoted to lieutenant commander. Kathryn Janeway has been relying on his judgement for the past nine years. I’ve placed the promotion in August 2374, so she seems to be referring to 2365.

Tuvok says in VOY “Phage” that he’s been observing Janeway for the past four years. Since I have the story in December 2371, I suggest he began his observations in 2368 (or very late 2367).

Sometime between 2371 and 2374, Tuvok becomes a grandfather for the first time, when his son Sek has a daughter called T’Meni, as explained in VOY “Hunters.”

Tuvok celebrates his birthday in VOY “Fury”. Janeway says he’s “nearly at the big three digits.” I’ve placed the story in 2377, so Tuvok ought to be about 114 Earth years old based on the evidence so far. If he’s 99 in Vulcan years, then they each must last at least 1.15 Earth years.

Tuvok has to tackle pon farr in VOY “Flesh and Blood,” which I’ve also set in 2377 (in October). If there is a strict seven Earth years mating cycle, then maybe:
Pon farr Earth year
15th 2377
14th 2370
13th 2363
12th 2356
11th 2349
10th 2342
9th 2335
8th 2328
7th 2321
6th 2314
5th 2307
4th 2300
3rd 2293
2nd 2286
1st 2279

These dates don’t fit very well with any of the other information, even assuming that Paris and Kim are completely wrong in their speculations about Tuvok’s age at the beginning of VOY “Alice”.

Other Suggestions

ENT “Home” establishes that Vulcan is 16 light years from Earth. If you look at a list of the nearest stars to our own, there are a number of stars at about that distance, including 40 Eridani. Although it has never been definitively stated that Vulcan orbits this star, I would draw your attention to a letter published in the July 1991 issue of Sky & Telescope, signed by Gene Roddenberry himself. Although it only considers 40 Eridani and Epsilon Eridani as candidates for Vulcan’s sun: “We prefer the identification of 40 Eridani as Vulcan’s sun…” seems a pretty clear endorsement. 40 Eridani has also been identified in a number of other “unofficial” publications. Placing Vulcan somewhere else (and the distance requirement makes a couple of very unlikely red dwarf stars, or Groombridge 1618, or maybe 70 Ophiuchi the only other practical options) would require some extremely convincing arguments.

Constructing a Calendar

To save scrolling about, I’ve started a new page, My Vulcan Calendar.

The end result is featured in the calendars page spreadsheet.

My Vulcan Calendar

by StrauchiusStrauchius on 09 Feb 2011 13:19, last updated on 06 Jul 2017 14:21