Paint a ceiling a beautiful shade of pale blue, and you may just feel as though you’re gazing up at a pure, tranquil sky. But what colour is the sky really?

Well, it’s not strictly blue. Sunlight actually consists of all colours of the rainbow (even red, orange and purple). As it passes through our atmosphere, the light is absorbed by gases and particles in the air and then radiated out in different directions. The short, blue wavelengths are scattered more widely, which is why the sky appears blue.

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