I was going to answer your question about what makes the sky blue, but when I went online, I found an answer that was so much better than I could have written, I decided to just put the link here.

This is NASA’s explanation for why the sky is blue:

If you want a more in-depth explanation, I recommend you read this one:

In summary, the sky is blue because of light scattering. When light hits the molecules in the air, highenergy blue light is more likely to scatter (bounce off in all directions) while low-energy red light is more likely to continue going straight. When we look up, we see all the blue light that has been scattered. When we look to the horizon, the light we see had to travel further, so most every color of light gets scattered by the time it reaches our eyes, so the horizon appears white, the mixture of all colors.

The reason the sky is blue has to do with tiny particles that float in the air and the way that sunlight interacts with these particles. Our sunlight is made up of the whole rainbow of colors red, orange, yellow, green, blue, and violet. When all of these colors of light are combined, they make the white light that we see on earth.

But when you look up into the sky, you see blue. The reason is that light bounces around on particles suspended in the air (mostly water molecules and dust), but the blue and violet colors are scattered more than the other colors. The scattering of the light means that more of this light escapes down to you and your eyes as you are looking up. Because the sun emits a greater amount of blue light than violet light, blue is the dominant color you see.