Why is the sky Blue?

The Earth’s atmosphere contains tiny

molecules of gas and dust particles. Sunlight

entering the atmosphere hits these molecules

and dust particles. Colours with longer

wavelengths, like red and yellow, can pass

through the atmosphere without being

scattered by these molecules of gas and dust

particles. But the colour blue, with its shorter

wavelength, is scattered by the gas molecules

and the dust in the upper atmosphere.

This is why the sky appears blue.