Inspired by this question:

The introduction to the Enterprise episode "In A Mirror Darkly" ends with an animation of the Terran Empire's sword-through-the-Earth logo. It shows the Earth spinning in the opposite direction that it spins in real life, so the Sun would rise in the west and set in the east. (I think I remember noticing that when I first watched the episode.)

Is this:

  1. An error by the production crew
  2. Just a cool little tidbit that they hoped the fans would notice, or
  3. An indication that the Earth really does spin in the opposite direction in the Mirror Universe?

(My personal bet is on #2, but I have nothing to back that up. #1 seems unlikely.)

EDIT : The most likely evidence for #3, if there is any, would be a scene showing Earth in the Mirror Universe actually rotating in the opposite direction.

  • You do realize that which way the Earth rotates depends on which way up you look at it? By convention, we usually put the north pole at the top, but that's not an objective truth - just a convention. Perhaps in the Mirror Universe the convention is to put the south pole at the top. Feb 19, 2018 at 8:12
  • 1
    @HarryJohnston: Yes, I'm aware. The intro clearly has north at the top. Feb 20, 2018 at 7:09
  • D'oh! You can see the geography. One might argue that it isn't spinning in the opposite direction, the geography is just backwards - so Europe is in the southern hemisphere - but that's a distinction without relevance. My bad. Feb 20, 2018 at 18:54
  • @HarryJohnston The video clearly shows north at "top" and the Earth rotating backwards. Looks like the mirror universe inhabitants followed the same convention as us.
    – RichS
    Nov 30, 2019 at 21:36

3 Answers 3


It wouldn't surprise me that much if the production crew either neglected to specify the direction of rotation (i.e. it wound up being chosen at random), or got it wrong, since for a lot of people it's not that hard to get your directions mixed up when figuring out which way the Earth rotates. However, I would agree that option #1 is considerably less likely than #2 or #3.

Now, unless someone shows up with a reference to some event in Star Trek canon which actually depicts the rotation of Earth in the mirror universe, or something that could be used to imply it (e.g. a scene occurring at a particular time of day in which the position of the sun can be established), I don't think you can make any sort of definitive claim about option #3. Certainly there is no physical reason that the Earth couldn't spin in the opposite direction (with respect to the orientation of its geography) in the mirror universe; in fact, there's no physical reason the Earth couldn't have been spinning in the opposite direction in our universe. As far as we know, the direction of Earth's rotation is probably derived from the angular momentum of the dust cloud that formed the solar system, and that has as much chance of being in one direction as any other.

Also, keep in mind that the mirror universe is meant to suggest what our universe would be like under a "morality reflection," not an actual physical reflection. Otherwise the writing on the mirror universe ships would be backwards, the characters would be mostly left-handed, and so on.

However, for a couple of reasons, I would guess that the mirror universe Earth does rotate the other way:

  • In-universe: the Terran Empire presumably would have patterned their animated logo after the rotation of their own planet. While I could potentially see one or two people on the production staff of Star Trek overlooking that little detail, there's no way it would have escaped from the billions (trillions?) of people in the actual Terran Empire. And even if the logo was designed by one person and imposed by fiat on the rest of the empire, it stands to reason that that one person would have taken care to get the details right, more care than would be justified for a brief clip in a TV show.
  • Out-of-universe: it's probably a little pun by the production staff. Despite the fact that the "morality reflection" is the main difference between our universe and the mirror universe, it still makes sense to make little things opposite between the two universes where it doesn't break internal consistency.
  • The first time we saw the Mirror Universe was in the TOS episode "Mirror, Mirror". We saw the USS Enterprise orbiting the Halkans' planet from left to right, switching to the ISS Enterprise orbiting from right to left. Did the planet's rotation reverse as well? Jan 9, 2012 at 23:25
  • I actually don't know, I haven't seen that episode in years. Someone else will have to address that.
    – David Z
    Jan 9, 2012 at 23:29
  • And that someone else is me, a couple of years later. I just watched the episode, but with the reworked special effects. The Enterprise changes the direction of its orbit, but the planet continues to rotate in the same direction. I still don't know what the planet did in the originally aired episode, though. Apr 14, 2014 at 2:15

If you reverse everything, then you can claim there shouldn't be first contact in first place (Boolean Reverse).
Script writers wanted a different way to tell story, so they introduced it.
I'll go for #2 too..

  • I don't know what you mean by "Boolean Reverse". I'm just talking about the rotation of the planet. Jan 8, 2012 at 23:48
  • 2
    He is telling that only story should be mirrored..
    – user931
    Jan 8, 2012 at 23:50
  • Yup. There's no base to tell laws of universe & natural happenings were reverse too.
    – user11147
    Jan 8, 2012 at 23:53
  • @SachinShekhar: What? Jan 9, 2012 at 3:14
  • Do you have evidence for #2 or is that just a guess?
    – RichS
    Nov 30, 2019 at 21:37

Let's make it easy and say everything in our universe is "normal" and the mirror ones are prime. The Enterprise is in our universe and the Enterprise Prime is in the mirror one.

It's a nod and wink to viewers and a little extra effort to say, "It's a mirror universe, it's backward."

Mike Okuda was Scenic Art Supervisor for Enterprise and in charge of the remastering of the FX for the original Star Trek. (For reference, he and Rick Sternbach wrote the technical guides for the newer shows and the actual writers' tech guides, so he not only knows Trek canon, his job for over two decades was to define it.) He was responsible for much of the look of Trek for his time working on the different shows.

With this level of expertise working on the show, it makes it almost impossible to have a mistake like having the Earth rotate in the wrong direction. In addition, any FX studio that does space shots will have a stock set of commonly used models, and Earth would be one of those. It's as much their job to know how Earth rotates as it is for a Doctor to know how to use a stethoscope. So if it's rotating backwards, someone, somewhere along the line, would have to specify that. It is not an accident.

As for it being intended to say that Earth Prime rotates backwards, we can check that by looking at footage from the mirror universe that was created before and after that episode to see what the "rule" for planet rotation in the mirror universe was before and after this episode was made.

In the sequence in the original Star Trek episode Mirror, Mirror, during the sequence when the landing party beams from one universe to the other, the Enterprise orbits left to right and the Enterprise Prime orbits right to left. However, bot the Halkan Homeworld and the Halkan Homeworld Prime orbit in the same direction.

We can check after that episode by looking at the remastered version of Mirror, Mirror. In the remastered version, we see the same change in direction for the Enterprise and the Enterprise Prime. There is no change in direction between the rotation of the Halkan Homeworld and the Halkan Homeworld Prime.

It's worth noting, though, that in the original version, both planets rotated right to left and in the remastered version, they both rotate left to right. Perhaps this is a bit of a nod, as well, to the symmetry of the universes.

This shows they not only intended to keep the different orbital direction matched, but that they could have changed the rotation if they wanted, from one universe to the other but they did not!

It also shows the rule for planetary rotation is the same for both universes.

  • Ah, but the Halkans themselves are the same principled pacifists in both universes. Jan 11, 2012 at 1:28

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