Why are galaxies round as a pizza instead of round like a sphere?

Question

Why are galaxies round as a pizza instead of round like a sphere?

In: Physics

Answer 1

Because spinning.

The same thing is happening within our solar system. All of the planets are spinning around the Sun in “pizza” formation, not as a sphere.

Fun fact: It’s the same reason that the Earth technically isn’t a sphere. It’s an oblate sphereoid. That means it’s round… but a little bit wider in the middle than top-to-bottom.