Why do galaxies look like they spread out in a single plane (ie, why do they look more like frisbees than spheres)?
In: Physics
The reason many galaxies are flat is because of the conservation of angular momentum. When objects revolve around the center of gravity, they have angular momentum. Given enough time, a rotating body of stars may flatten into an overall disk shape.
This band of stars can be seen with the naked eye in places with dark night skies. That band comes from seeing the disk of stars that forms the Milky Way from inside the disk, and tells us that our galaxy is basically flat.
[https://www.reddit.com/r/explainlikeimfive/comments/9wnvfb/eli5_why_are_galaxies_flat_i_would_imagine_that_a/](https://www.reddit.com/r/explainlikeimfive/comments/9wnvfb/eli5_why_are_galaxies_flat_i_would_imagine_that_a/) – 2 years ago
[https://www.reddit.com/r/space/comments/2zd52d/why_are_galaxies_flat/](https://www.reddit.com/r/space/comments/2zd52d/why_are_galaxies_flat/) – 6 years ago
[https://www.reddit.com/r/askscience/comments/gv6rj9/why_galaxies_are_flat_why_there_are_no_spherical/](https://www.reddit.com/r/askscience/comments/gv6rj9/why_galaxies_are_flat_why_there_are_no_spherical/) – last year
[https://www.reddit.com/r/askscience/comments/awaqky/why_are_galaxies_a_flat_disk_and_not_a_sphere/](https://www.reddit.com/r/askscience/comments/awaqky/why_are_galaxies_a_flat_disk_and_not_a_sphere/) – 2 years ago
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