Explain · analogy · Like I'm five version
How a rainbow works in terms of a disco ball
Why does the sky turn into a giant, colourful disco ball when it rains?
A rainbow is like a disco ball because both use light and little shapes to make magic. When a bright, white sunbeam hits a raindrop, the drop acts exactly like a tiny glass mirror on a dancing ball. The light goes inside, bends to say hello to the water, and then hops back out. Just as a disco ball takes one light and splits it into many sparkles, a raindrop splits the sun into all the pretty colours we see.
The raindrop is like a smart little prism that knows how to sort colours. It sends the red light out at one angle and the violet light at another, just like how a mirror on a ball sends a dot of light to the rug, the wall, or the cat. If the sun is at your back and the rain is in front of you, you get your own private light show. You are the only person who can see your special rainbow, just like you are the only one who can catch a specific twinkle from a spinning ball.
You cannot actually touch a rainbow because it is just a trick of the light playing in the sky. If you run towards it, it will keep moving further away to stay in the right spot for your eyes. It is a big, beautiful puzzle that disappears once the rain stops and the clouds pack up their glitter. It is the best party trick the sky knows how to do without needing a plug socket or a grumpy DJ.
Where the analogy breaks downA rainbow is caused by refraction and reflection inside water drops, but a disco ball uses flat mirrors to bounce light without changing its colour.