James Webb Space Telescope reveals that most galaxies rotate clockwise

Posted by instagraham 3/31/2025

James Webb Space Telescope reveals that most galaxies rotate clockwise(www.smithsonianmag.com)

356 points | 310 commentspage 2

zurfer 3/31/2025|

Complete layman's question: If we would indeed be inside a black hole wouldn't we be able to observe new energy and matter entering?

Related question: the horizon of a black hole is expanding when the mass increases. Could this map to the expansion of our universe, which seems to expand faster and faster?

floxy 3/31/2025||

>If we would indeed be inside a black hole wouldn't we be able to observe new energy and matter entering?

https://en.wikipedia.org/wiki/Dark_energy

jagged-chisel 3/31/2025|||

I don’t think we know enough about relative time from outside our universe. Our 15 billion years could be the parent universe’s one second.

thro1 3/31/2025||

What about black hole new mass/energy converting into orthogonal space ??? ( ..is it part of Principia Unitas ??).

snitty 3/31/2025||

If we were on the other side of those galaxies, wouldn't they look like they were spinning counter-clockwise? Or are they measuring spin some other way?

scribu 3/31/2025||

The point is that you’d expect a roughly even distribution of clockwise and counterclockwise spins, not all of them to rotate in the same direction.

throwawaymaths 3/31/2025|||

wouldn't it be the case that you would see almost exactly 50/50 if all galaxies had parallel axes and rotated in the same absolute direction?

1oooqooq 3/31/2025|||

why? if you subscribe to big bang then all matter got the same "initial kick". would be easier to assume same spin?

mnky9800n 3/31/2025|||

From my understanding, the big bang requires that the proto-universe was in a completely homogenous state that was then pushed out of that equilibrium for some reason. But that reason doesn't require non-zero angular momentum. It only requires that a the proto-universe was homogenous and now the universe isn't. And that is what separates pre and post big bang. I could be wrong, I am not a cosmologist. Would be happy to hear from one though.

aurareturn 3/31/2025|||

So what caused the "initial kick" to favor one side?

Aardwolf 3/31/2025|||

What causes a perfectly symmetric ball on top of a perfectly symmetric hill to roll down via one side? (Probably quantum randomness if everything else is perfectly symmetric)

pixl97 3/31/2025|||

What caused this universe to favor matter over anti-matter?

So many unanswered questions.

iainmerrick 3/31/2025|||

I was wondering the same thing -- "direction of spin" is ambiguous on its own, you also need to pick which direction is up.

But if objective spin directions are roughly evenly split because the universe is isotropic, the spins from our viewpoint ought to be evenly split as well.

If they're not evenly split, the universe must have a preferred axis, which would be an amazing discovery. I guess if the preferred axis just happens to align with our own galaxy, that would support the alternative theory that it's due to an observation effect such as doppler shift.

Either way, it's incredibly cool to have such a simple but totally unexpected observation pop up out of nowhere.

RotationPedant 3/31/2025|||

That is correct, "clockwise" only makes sense relative to a single observer: on Earth we set up out coordinate system so that the Milky Way's directed axis of rotation points one way, and most galaxies have it pointing the other way. "Clockwise / counterclockwise" makes sense for images coming from telescopes but it's not cosmologically meaningful.

Note that this is not that easy to determine:

  When done manually, the determination of the direction of rotation of a galaxy can be a subjective task, as different annotators might have different opinions regarding the direction towards a galaxy rotates. A simple example is the crowdsourcing annotation through Galaxy Zoo 1 (Land et al. 2008), where in the vast majority of the galaxies different annotators provided conflicting annotations. Therefore, the annotations shown in Fig. 1 were made by a computer analysis that followed a defined symmetric model (Shamir 2024e).

The point is that we would typically assume a 50-50 ratio regardless of where you are in the universe.

Patient0 3/31/2025||

The actual paper makes more sense: "the number of galaxies in that field that rotate in the opposite direction relative to the Milky Way galaxy is ∼50 per cent higher than the number of galaxies that rotate in the same direction relative to the Milky Way."

credit_guy 3/31/2025||

I wonder if it’s already April’s Fools Day in some parts of the world. The hands of a clock move clockwise if seen from the front, but counterclockwise if seen from the back.

coffeecantcode 3/31/2025||

Coming from a place of complete ignorance, are there indicators in galaxies that determine a top/bottom for lack of better words?

I can’t think of any that would make much sense as top/bottom would mean that there needs to be a relative universal point to reference and as far as I know, that doesn’t exist.

tiagod 3/31/2025||

The article states that the problem is that they looked at random galaxies, 1/3 were moving one way and 2/3 the other.

If the distribution was truly random, and the universe is isotropic, we should see roughly 50/50.

symmetricsaurus 3/31/2025||

The result is only significant to 3.39 sigma. Pretty good chance this is just a random fluctuation that will go away if you look at more galaxies.

BlackFly 3/31/2025|

This was also my thought, since selection bias seemed like a good explanation as well. The survey only covers 220 square arcminutes out of a total of about 148 million. Interesting data point though, definitely seems like something that one should measure!

CPLX 3/31/2025||

I was reading this and thinking, what if there’s no such thing as scale. Like, obviously there is in some sense, but what if there’s some kind of theory of relativity for scale as well, maybe scale is relative to gravity and gravity isn’t constant or something like that. So for example a universe as detailed as ours with sentient beings and all that could exist inside a quark, and we could in fact be living inside a proton or something, seen from someone else’s perspective. And it’s that level of detail, forever, in every direction.

Or maybe not, anyways back to work.

DonHopkins 3/31/2025||

Unless you're looking at them from the other side, in which case they rotate counter-clockwise!

Or maybe they're just billboard sprites, always facing the camera, with clockwise animations.

_kst_ 4/1/2025||

The study is based on 263 galaxies.

It should be fairly easy to determine the rotation direction of any (spiral) galaxy we can see, based on reasonable assumptions about the relationship between rotation and the configuration of the spiral arms. There should be thousands or millions of visible galaxies for which this could be determined (out of the estimated 2 trillion galaxies in the observable universe). Perhaps I'm missing something, but why bother reporting a result from such a tiny sample?

It should also be possible to derive more detailed information that just clockwise vs. counter-clockwise. The rotation of a galaxy defines a direction (the galaxy's rotational north pole) and a point on the surface of an imaginary sphere. This could be determined by the galaxy's apparent rotational direction, its orientation, and its position in the sky. It would be interesting to see a plot of those points. In principle, they should be random. (If the points spell out "Go stick your head in a pig", I'll be very sorry that Douglas Adams didn't live to see it.)

alenrozac 3/31/2025||

At this point I'm open to believing our Universe is in a black-hole-like structure.

belter 3/31/2025||

This study does not conclusively prove most galaxies rotate clockwise...Just has a somewhat strong observation of asymmetry. Other studies that the paper mentions, and criticizes, did not observe it.

Study is at around 3σ (like 62 heads in 100 flips). It is more likely that future studies disprove it, and this is an issue with the methods, if I am of the betting type... :-)

1970-01-01 3/31/2025|

Spin a coin on top of a glass table. Observe it from the top, and it spins either clockwise or anticlockwise. Observe it from the bottom and it's the opposite. There are no tables in space. Objects tumble while rotating. It seems we are measuring rotations using a fixed perspective when there is no reason to do so

https://www.comsol.com/blogs/why-do-tennis-rackets-tumble-th...

hnuser123456 3/31/2025||

If there were 10 pennies and 7 of them were spinning the same direction, you might say one direction appears to be favored.

Spiral galaxies spin, they do not tumble unless hit by another galaxy.

Elliptical galaxies are like gravitational convection and don't really have cohesive "rotation", however.

richwater 3/31/2025||

The paper measures rotation relative to the Milky Way galaxy.

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