1 minute read
WHY IS THE SKY BLUE?
from National Trust: Out and About Sky Explorer: A children’s guide to clouds, constellations and other a
by Nosy Crow
The gases that make up our atmosphere are colourless, but on a clear day the sky is a beautiful blue. You may have heard some people say this is caused by the way light reflects off the ocean, or by water droplets in the atmosphere, but the truth is it’s all down to the sunlight!
The white light that human eyes can see is made up of seven different colours – red, orange, yellow, green, blue, indigo and violet – even though normally we don’t see them all separately.
Light moves in waves. The longer waves make light that is more red, and the shorter waves make light that is more blue. Together, all these waves make up white light.
VIOLET INDIGO BLUE GREEN YELLOW ORANGE RED
When rays of white light from the sun reach the Earth, they hit the tiny particles of gas and dust in the atmosphere, which scatter (or split) the light into its different colours. The shorter blue waves of light are scattered much more than the longer red ones.
This means that when we look up, our eyes see a lot more of the blue light than red light, making the sky a bright blue.
This is called ‘Rayleigh scattering’, named after the scientist Lord Rayleigh who discovered it.
