Science
What is Rainbow?
A rainbow is an arc of colours that appears in the sky when sunlight passes through raindrops. Each droplet acts like a tiny prism, bending and splitting white sunlight into its separate colours — red, orange, yellow, green, blue, indigo, and violet.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains rainbow.
Key things to understand
- 1Sunlight looks white but is actually a mix of all the colours.
- 2When sunlight enters a raindrop it bends (refracts), reflects off the back, and bends again as it exits — splitting into its colours.
- 3Each colour bends by a slightly different amount, so they fan out into the familiar band.
- 4You see a rainbow when the Sun is behind you and rain or mist is in front of you.
- 5A rainbow is really a full circle of colour; we usually see only the arc above the horizon.
Frequently asked questions
- How is a rainbow formed?
- Sunlight enters raindrops, bends and reflects inside them, and splits into its separate colours on the way out. Millions of droplets doing this together form the arc of a rainbow.
- Why is a rainbow curved?
- Rainbows form at a fixed angle (about 42°) from the line between the Sun and your eyes. That set of angles traces out a circle, so the rainbow appears as an arc.
- Why does a rainbow have its colours in that order?
- Each colour of light bends by a different amount in water — red bends least, violet most — so they always separate into the same order, red on the outside to violet on the inside.