How's a rainbow made in the sky?

The reason that you get a rainbow, is that sunlight shines into a raindrop. Raindrops are very tiny and the surface of it is like a mirror. As the light waves go into a raindrop, they hit the mirror like surface and reflect. The light bounces off the back inside surface of the raindrop and comes back out of the front. Now if you've ever seen a prism, what that does is split white light into all the colours of the rainbow. White light is actually a mixture of lots of different colours. When the light comes back out of the front of the raindrop, it splits up into all the different colours of white light, and that's how you get a rainbow.