Scienceville
Rainbow Magic
A rainbow is not a thing you can touch. It is a trick of sunlight, raindrops and your own eyes! Let's discover some of its secrets.
Did you know?
A rainbow is really a full circle! From the ground, the land hides the bottom part. From an aeroplane or a mountaintop, people can sometimes see the whole ring of colours.
Sometimes you can spot a double rainbow. The second bow is fainter, and its colours are in the opposite order. Red is on the inside instead of the outside!
Rainbows can appear at night too! A moonbow is made when moonlight shines through water drops. It usually looks white to us, because the light is too dim for our eyes to see colours.
Try this: CD Rainbow
Find an old CD or DVD. Hold it with the shiny side up in sunlight or under a torch. Tilt it slowly. Can you see bands of colour? Now tilt it so the light bounces onto a white wall. How many colours can you count? Which colour is easiest to see? Remember: never look straight at the Sun.
Go further: Newton's Seven Colours
Long ago, the scientist Isaac Newton studied how sunlight splits into colours. At first he named five colours. Later he added orange and indigo to make seven, to match the seven notes of a musical scale (like sa, re, ga, ma, pa, dha, ni!). A 'Newton disc' is a circle painted with all seven colours. When it spins very fast, it looks whitish-grey, because your eyes cannot keep up and the colours blend together.