Theory on why the sky is Blue

Well, I have a theory which could result as an answer to as why the sky is Blue. What I think is that the sky is Blue because the Earths water, reflects of the light given by the sun, which would also explain why the sky is Black at night since there is no sun. There is an experiment that you can try to prove this too. If you put a brightly colored tooth brush or some other brightly colored object into a cup which in the inside is White, and    pour some water in, the water will turn what ever the color of the object that you put in. It has the same principle as to why the sky is Blue but only on a smaller scale.

If you have your own theories on why the sky is Blue, feel free to post it in the comments.