Why does the Milky Way look curved?

Let me pose the following question to you:

How is it possible to get two points in the sky — 180 degrees apart — into the same image?

It’s not possible, not unless you distorted something along the way! In this case, we had to distort the composite, stitched-together image in order to display the entire path with a flat horizon! This is a complicated task, similar to the reason why it’s impossible to make a flat map of a sphere that simultaneously has all the properties you’d desire!