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

It is constructed from measurements. As long as one observes many stars and can measure their distance and angle from (say) the earth’s viewpoint, it is a matter of geometry to place them on a 3D map. With software, this map can be rotated etc so we get a “constructed” view of the galaxy.