eli5 How do we know how our galaxy looks like if we’re part of it ?

Question

We can only see ourselves if we look in the mirror or our photos or like we can see how our planet looks because of the satellites . But how can we see our galaxy

In: 10

Answer 1

Your mirror is a good analogy. Kick up a cloud of dust while looking in that mirror. You will still see yourself and a lot of dust particles. The density of the galaxy is so low that we can see a good percentage of it even though we are in it. We can calculate where these things are and where they are going accurately enough to build a model of it. It may be easier to grasp if you think about the solar system. We are also within that but have a very good idea of what it looks like.