Why are sunsets red? © Getty Images

Why are sunsets red?

The colour of the sky when the sun setting is all down to Rayleigh scattering.

Asked by: Anonymous


Tiny suspended particles in the atmosphere – and the gas molecules themselves – cause the light from the Sun to be split into its constituent wavelengths (this is called Rayleigh scattering). The shorter, blue wavelengths are scattered more, so the sky appears bluer the further from the Sun you look. At sunset, the sky at the horizon looks red because the light there is scattered least.


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