eli5 How do we know what other milky ways look like?

Question

So I’ve been watching a lot of video’s about how small we are compared to the universe. ( like [this](https://www.youtube.com/watch?v=9rrG5Nppaew&ab_channel=DANIELKAMARUZAMAN) ). And I don’t understand one thing. How do we know what our milky way looks like? And how do we know what the other millky ways look like?

In: Earth Science

Answer 1

If you spill milk it looks like a circle from the top.

But if you look at it from the side of the table, it looks long like a line.

Same thing with our galaxy. We see all the other stars near the middle as a bright line in the sky. And stars are more clumped together in the center or our galaxy, like milk chunks.