This is one of those weird things where our perception is dictated by our cultural biases.
If you were an intelligent alien coming to earth for the first time from a planet with no rainbows, you’d see one and think “Oh, what an interesting phenomenon! A circular refraction partially obscured by the ground!” - because of course there’s no way that kind of optical phenomenon could be anything other than completely symmetrical. It’s obvious if you think about it.
But as a human, right from being a child every single portrayal of a rainbow has them as an arc, and we were never given reason to think about it from an analytical perspective. So we never did.
This is one of those weird things where our perception is dictated by our cultural biases.
If you were an intelligent alien coming to earth for the first time from a planet with no rainbows, you’d see one and think “Oh, what an interesting phenomenon! A circular refraction partially obscured by the ground!” - because of course there’s no way that kind of optical phenomenon could be anything other than completely symmetrical. It’s obvious if you think about it.
But as a human, right from being a child every single portrayal of a rainbow has them as an arc, and we were never given reason to think about it from an analytical perspective. So we never did.