Explain · analogy · Serious version
How a rainbow works in terms of a disco ball
A rainbow is the process of sunlight refracting, reflecting and dispersing through raindrops to create a visible spectrum of light.
Think of a rainbow as a disco ball suspended in the sky, where individual raindrops act as the tiny mirrored facets reflecting light back to the dancefloor. Sunlight enters each spherical droplet and slows down, bending as it moves from air into water. Just as a beam hitting a mirror bounces off at an angle, the light reflects off the back of the drop. Because different colours of light have different wavelengths, they bend at slightly different angles, causing the white light to spread out into a fan of distinct colours.
The sky essentially becomes a giant Saturday night at a village hall, with every raindrop playing the role of a glittery tile spinning in the dark. As the light exits the droplet, it undergoes a final refraction, widening the separation between red and violet. Millions of drops work in perfect synchronisation, casting that familiar arc of colour across the horizon. You are only ever seeing the reflection from the drops positioned at a specific forty-two degree angle from your eyes, meaning every spectator is dancing under their own private light show.
The display remains tethered to your perspective, shifting as you move, much like how the light patterns from a disco ball change if you stumble across the floor. Once the sun drops too low or the rain clears, the music stops, the mirror ball is packed away, and the sky returns to its mundane, monochrome state.
Where the analogy breaks downA rainbow is a projection caused by light travelling through water, whereas a disco ball is an opaque object that simply reflects light off its surface.