Well, I was always told that the sky wasn't blue, and that it was just the sun reflecting off of the ocean, making the sky seem blue, but others have told me that it is not the ocean that is reflecting off of the sky, but something called blue light. Basically, blue light is strewn in all directions by the extremely small molecules of air in the Earth's atmosphere, making the sky seem blue. When the sky is not blue, like, if its violet or something, it is because of the violet lights that reflect from the sun. ~Hope I helped!~
The sky is blue because when light from the sun enters our atmosphere, mostly blue light is refracted towards where we can see it, while most other colors are not. It's reflected by the atmosphere more because blue has a shorter wavelength, so it will collide with particles more often.
