Rainbows seems more like magic than science. What else could explain the skies on the right turning into the scene on the left?

To repeat the words of artist Gilbert Baker:

We needed something to express our joy, our beauty, our power. And the rainbow did that. The rainbow is a part of nature, and you have to be in the right place to see it. It’s beautiful, all of the colors, even the colors you can’t see. That really fit us as a people because we are all of the colors. Our sexuality is all of the colors. We are all the genders, races, and ages.