What causes a rainbow?

Rainbows happen when water droplets and sunlight play a game together.

Imagine you're splashing in a puddle on a sunny day, that's like what happens in the sky after it rains. The sunlight comes down, but instead of going straight through the water droplets, it bounces around inside them, kind of like how light reflects off a shiny ball.

When sunlight hits a water droplet, it slows down and bends, this is called refraction. Then, the light bounces off the back of the droplet and comes out again. As it leaves, it bends once more. This bending makes the white sunlight split into different colors, like how a prism separates light into a rainbow.

Each color takes a slightly different path, so when you look at the sky from just the right angle, you see them spread out in an arc, red on top, violet on the bottom, with all the pretty colors in between. It's like the droplets are little artists painting their own tiny rainbows for you to enjoy!