<p>I remember in either the Pioneer or the Voyager flyby, they discovered that Saturn's rings have spokes. The radial features turned out to be dust and static electricity, but seeing the apparently impossible in front of you is disconcerting. I remember feeling quite distressed about the bars in in galaxies when I was in 8th grade.</p>
<p><a href="https://i.sstatic.net/AJaz5T68.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/AJaz5T68.png" alt="" /></a></p>
<p>Did astronomers say, &quot;There's something happening in galaxies that's definitely impossible and we have no explanation?&quot;</p>
<p>Or what?</p>

CC BY-SA 4.0
2024-09-05T03:43:24.647Z
Why do you think bars are impossible without dark matter? What evidence do you have that any astronomers thought that?
Peter Erwin
CC BY-SA 4.0
2024-09-05T12:46:51.167Z
@PeterErwin is there another mechanism? That's my question.
Miss Understands
CC BY-SA 4.0
2024-09-05T15:28:35.123Z
Theoretical arguments and $N$-body simulations suggested that rotating galaxy disks were intrinsically gravitationally unstable and naturally formed perturbations like spiral arms and (often) bars. One of the persistent questions is actually "why don't *all* galaxy disks have bars?" In the 1980s it was suggested that sufficiently massive round halos (e.g., dark-matter halos) would *prevent* bar formation. More detailed simulations in the early 2000s showed this wasn't necessarily true.
Peter Erwin
<galaxy><spiral-arms>
Before they hypothesized dark matter, what did astronomers attribute the bars in barred spiral galaxies to?
Miss Understands
# Before they hypothesized dark matter, what did astronomers attribute the bars in barred spiral galaxies to?

(Asked by: username_0 on 2024-09-04)

I remember in either the Pioneer or the Voyager flyby, they discovered that Saturn's rings have spokes. The radial features turned out to be dust and static electricity, but seeing the apparently impossible in front of you is disconcerting. I remember feeling quite distressed about the bars in in galaxies when I was in 8th grade.

[![](https://i.sstatic.net/AJaz5T68.png)](https://i.sstatic.net/AJaz5T68.png)

Did astronomers say, "There's something happening in galaxies that's definitely impossible and we have no explanation?"

Or what?

**Tags:** galaxy, spiral-arms
> **Comments:**
> **username_1**: Why do you think bars are impossible without dark matter? What evidence do you have that any astronomers thought that?  
> **username_0**: @PeterErwin is there another mechanism? That's my question.  
> **username_1**: Theoretical arguments and $N$-body simulations suggested that rotating galaxy disks were intrinsically gravitationally unstable and naturally formed perturbations like spiral arms and (often) bars. One of the persistent questions is actually "why don't *all* galaxy disks have bars?" In the 1980s it was suggested that sufficiently massive round halos (e.g., dark-matter halos) would *prevent* bar formation. More detailed simulations in the early 2000s showed this wasn't necessarily true.  

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## 0 answers

