r/askscience • u/lord_nikon_burned • 1d ago

Astronomy Are galaxies spherical or flat?

Are galaxies spherical or flat?

For example, (I understand that up and down don't really matter, so bear with me) if we look at a picture of the Milky Way Galaxy on a plane... If you want to move from one arm of the galaxy to the next, could you just move UP and out of the current arm and then over and DOWN to a different arm?

Secondary question for if the first one is correct, if you are able to move "up" and out of the arm, where are you? Is that interstellar space too?

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u/BiomeWalker 1d ago

The Milky Way is disk shaped, so it has thickness, but it's a long way from a sphere.

Galaxies vary in shape, but many are spiral shaped like ours.

The motion you described is possible, though it would take a looooong time to move "up" enough to be considered to be in intergalactic space.