Science
How do rainbows form?
A rainbow forms when sunlight passes through raindrops, which bend and split the light into its colors. Each drop acts like a tiny prism, and together they spread sunlight into the familiar arc of red through violet.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how rainbows works.
Step by step
- 1Sunlight enters raindrops and bends (refracts).
- 2Different colors bend by slightly different amounts.
- 3The light reflects inside the drop and exits, split into colors.
- 4You see a rainbow with the sun behind you and rain ahead.
Frequently asked questions
- What causes a rainbow?
- Sunlight bending and splitting into colors as it passes through raindrops acting like tiny prisms.
- Why is a rainbow curved?
- Light reflects from drops at a specific angle all around, forming a circular arc centered opposite the sun.
- Why do you need the sun behind you to see a rainbow?
- The light must reflect back toward you from raindrops ahead, which only happens with the sun behind you.