The constellations appeared upside-down in Cuba, why?

May 10, 2014 7:21 PM

A friend of mine from Montreal just spent a week in Cuba, Cayo Coco. She says that when she was outdoors at night the constellations she's familiar with appeared to be upside down. Cassiopeia, for instance, looked like an M instead of a W. No, she wasn't stoned, drunk, tripping. Does anyone have an explanation for this?
posted by mareli to Science & Nature (19 answers total)

Uh... she was facing a different way from the way she usually faces?
posted by Behemoth at 7:27 PM on May 10, 2014 [8 favorites]

Yeah, that's sort of the entire point of that group of stars being called Cassiopia, in terms of mythology. She was so boastful that the gods punished her by throwing her up in the sky, where she has to spend half the time clinging to her chaise so she doesn't fall off.
posted by BlahLaLa at 7:37 PM on May 10, 2014 [1 favorite]

Presumably some constellations moved from one side to the other of the celestial equator with moving that far south? Just as all the constellations look inverted (and flipped) in the Southern Hemisphere as compared with the Northern.
posted by yoink at 7:38 PM on May 10, 2014

Cassiopeia rotates around Polaris and as long as you're in a place where it doesn't dip below the horizon for part of the year, at some times it will be a M and at some it will be a W.

Presumably some constellations moved from one side to the other of the celestial equator with moving that far south? Just as all the constellations look inverted (and flipped) in the Southern Hemisphere as compared with the Northern.

I can't make sense of this comment. The celestial equator and constellations don't change their locations in relation to each other. There are other constellations that we can't see in the northern hemisphere that you can start seeing the farther south you go, such as the Southern Cross. As you go south, northern constellations would disappear from your view. I don't know how they'd appear flipped or inverted.
posted by LionIndex at 7:48 PM on May 10, 2014

As you go south, northern constellations would disappear from your view. I don't know how they'd appear flipped or inverted.

Google "constellations upside down" or "constellations inverted Southern Hemisphere" and you'll find a zillion explanations. As someone who regularly travels between the hemispheres, I can assure you it happens.
posted by yoink at 7:54 PM on May 10, 2014

You could visualize this yourself in Free software like stellarium. It looks like in Cuba at this time of year, Cassiopeia spends much of the night below the horizon. not rising until after 1AM, while in Montreal it's visible all night. I wonder whether your friend, not knowing that Cassiopeia wasn't visible, misidentified other stars as that constellation.
posted by jepler at 7:56 PM on May 10, 2014 [1 favorite]

Or, accustomed to seeing it in the northwest sky early in the evening, saw it in a different orientation in the northeast sky late in the night. Looking north over the course of a night, it can change from looking like an E or Σ to looking like a 3 as the earth rotates.
posted by jepler at 8:00 PM on May 10, 2014

Google "constellations upside down" or "constellations inverted Southern Hemisphere" and you'll find a zillion explanations.

All that brings up is constellations that are rotated, not inverted. It seems pretty apparent that it's basically that people are used to looking south to view certain constellations, but then when they're in the southern hemisphere, they're facing north to see them. Therefore the constellations are upside-down. You can experience the same thing in the northern hemisphere by facing north, and then bending over backwards to view constellations near the celestial equator. Voila, they're upside down.

I don't think Montreal is far enough north that someone there would be looking south to view Cassiopeia, so that phenomenon is unlikely to be at play here.
posted by LionIndex at 8:42 PM on May 10, 2014

cuba is in the northern hemisphere, same as montreal. my best guess would be either that your friend was upside-down, or that many things appear upside-down in a communist workers' paradise; orion is doing a headstand and the big dipper pours its contents down upon you.
posted by bruce at 10:03 PM on May 10, 2014 [6 favorites]

From the Southern Hemisphere, any object or constellation that lies near the celestial equator (the imaginary line that divides the northern and southern halves of the sky) would appear both upside down and reversed left to right compared to a northern perspective.
posted by yoink at 10:09 PM on May 10, 2014

This is not a northern/southern hemisphere thing. This is a when-did-you-look thing. The entire night sky rotates 360 degrees through the course of any terrestrial day. This is because the Earth rotates. The point around which the sky appears to rotate is the North Star. At some point the Big Dipper or Cassiopeia will be on one side of the North Star, and 12 hours later on the other side. This is 100% normal and can be viewed even in the course of any clear night if you stay up all night watching the sky. The "M" or "W" are wholly dependent on the rotational position of the Earth, not your latitude. They will still demonstrate this equivalent apparent rotation even if the constellation spends 90% of its time below your local horizon, or never leaves the sky at all. The Earth's pole, after all, is defined as such because it is always pointing in the same direction, which happens due to the accident of human civilization being now to also point at Polaris. But the apparent rotation would still happen if we pointed at a different star, or if there were no visible star near the place where the pole points. Again, it is the rotation of the Earth itself that causes this illusion of motion.

If you or your friend wants a good, basic, plain language introduction to astronomy, I cannot recommend a better one than The Stars: A New Way to See Them by H.A. Rey (better known for the Curious George books).
posted by dhartung at 11:34 PM on May 10, 2014 [8 favorites]

appear both upside down and reversed left to right

I.e. rotated.
posted by effbot at 3:27 AM on May 11, 2014

I.e. rotated.

i.e., "inverted (and flipped)." Rotate a W, what do you get? An M. Invert and flip a W, what do you get? An M. And the point is that this doesn't happen in some kind of instantaneous "hey, presto chango" moment as you move from the Northern Hemisphere to the Southern Hemisphere--it happens steadily as you move around the great big spherical ball which is the Earth. I don't know enough about the place of Cassiopeia in the night sky relative to Montreal and to Cuba to know if that would account for the difference OP's friend saw, but it certainly could.

Think of it this way: imagine a very high East/West running wall. In the top of the wall is a weathervane in the form of an arrow, and it's pointing due north. So, if I stand on the North side of the wall and look up at the weathervane, what do I see. I see the pointy tip of the arrow pointing "up" and the feathered shaft of the arrow pointing "down." Now I walk through a door in the wall to the South side and someone says "hey, look up at the weathervane!" Now, by a miracle, it's upside down ("rotated" or "inverted and flipped"--take your pick): the pointy end points "down" (relative to my perspective) and the feathered shaft points "up." Of course, I could face away from the wall (south) and crane my head backward until I can see the arrow the same way I'd see it from the North side of the wall, but that, of course, would not be the natural response to someone saying "hey, look at the weathervane." The act of "looking at the weathervane" feels simply like "looking upward" (it's a tall wall, remember), but because of where I am relative to a line drawn perpendicularly down from the vane (or the constellation) to the sphere of the Earth, I'm automatically oriented to its image in such a way that when I'm north of that line (which in this case is marked by the wall) I see the arrow as pointing up, and when I'm South of that line I see it pointing down.
posted by yoink at 6:40 AM on May 11, 2014

In Cuba she would see the M lower in the sky. In the context of the horizon it would look much more M-like. From Montreal, Cassiopeia is nearly overhead when it's an M so it's kind of ambiguous - how do you distinguish M from W without a horizon? At the north pole, Polaris is overhead and Cassiopeia is always a W.

Also, I know we're not supposed to argue on AskMe but Yoink's "inverted and flipped" is really not a helpful way to think about how the constellations change as you cross the equator. What's happening there is that the observer has turned 180 degrees to look northward at constellations they usually see when looking southward. It's confusing enough without bringing imaginary mirrors into it.
posted by nixt at 10:05 AM on May 11, 2014 [1 favorite]

As dhartung pointed out, this is not a northern/southern hemisphere thing. Cuba is in the northern hemisphere. The equator runs through South America (hence Ecuador!)

Cuba is less than 250 miles from Florida.

Florida is over 1700 miles from the equator.
posted by ananci at 1:11 PM on May 11, 2014

i.e., "inverted (and flipped)." Rotate a W, what do you get? An M. Invert and flip a W, what do you get? An M. And the point is that this doesn't happen in some kind of instantaneous "hey, presto chango" moment as you move from the Northern Hemisphere to the Southern Hemisphere--it happens steadily as you move around the great big spherical ball which is the Earth.

Cassiopeia's a bad example. Most of the sites showing the effect show Orion (with the major stars labeled), which, in its "inverted and flipped" state is quite obviously just rotated, because the observer is turned around. They use Orion as an example because it's a familiar constellation near the celestial equator, so it's visible from both hemispheres. The orientation of the constellation depends on which way the observer is facing.

Otherwise, if there's no presto chango moment when you turn around, you're saying that the stars rearrange themselves as you move south even if you're facing the same direction the whole time, so that at some point, Orion looks like a cluster of stars instead of a constellation. So, if you're in say, San Diego (where I'm at) Cassiopeia is a W/M depending on the time of year, and I'm always looking north (more or less) to view it. If I walk backwards towards the equator, always keeping Cassiopeia in sight, at some point it'll start morphing to reverse itself? Just because I'm walking backwards? Based on what?
posted by LionIndex at 3:10 PM on May 11, 2014 [1 favorite]

I'm no expert, but this has nothing to do with N v S hemisphere. Montreal & Cuba are in the same one. Nor flipping, rotating, inverting, etc.
posted by LonnieK at 6:23 PM on May 11, 2014

Nor angle of view. Interplanetary angles of view are essentially the same from anywhere on earth. Or from Mars or Venus, for that matter.
posted by LonnieK at 6:30 PM on May 11, 2014

Best answer: Montreal and Cuba are both in the northern hemisphere, so it has nothing to do with crossing the equator.

Cassiopeia is a circumpolar constellation, which is visible all year. If you go out every night at midnight and find it, it'll be a W in May, a 3 in August, an M in November, and a Σ in February.

However, Cuba is so far to the south that Cassiopeia is not visible all night. This time of year Cassiopeia doesn't rise in Cuba until about 2AM, and is to the right of Polaris (and shaped like a 3) at dawn.
posted by fantabulous timewaster at 11:48 AM on May 12, 2014