All mysteries
Mystery #4Tier 2–3light

How does a rainbow form?

A rainbow appears out of thin air β€” no paint, no screen β€” a perfect arc of every colour, always when the Sun comes out during rain. Where do the colours come from, and why an arc?

A bright rainbow arcing across the sky
Photo: Divya Chinnasamy Β· CC0 Β· via Wikimedia Commons

Your guess

What do you reckon turns plain sunlight and falling rain into a band of colours?

Make a guess to unlock the hints and the answer.