Rainbow

A rainbow is a curved band of colours that appears in the sky when sunlight is bent and reflected by water droplets, usually after rain.

How it forms

When light enters a raindrop, it bends (refracts), reflects off the back of the drop, and bends again as it leaves. This splits white light into its colours — red, orange, yellow, green, blue, indigo and violet.

Appearance

Rainbows appear opposite the Sun, so they are often seen when the Sun is low and rain is falling in the distance.

Frequently asked questions

What causes a rainbow?

Sunlight bending and reflecting inside water droplets.

How many colours are in a rainbow?

Traditionally seven.