Why are sunsets red?

Asks Lucas Browning

Sunlight is a mixture of colours: red, orange, yellow, green, blue, indigo and violet. Each colour has a different wavelength. When the sun is setting over the horizon, it still lights up the sky. But from such a low angle, its lightwaves have to travel through a lot more of the Earth’s atmosphere. It’s a bumpy ride. Specks of dust and molecules of gas get in the way. They bounce away the shorter wavelengths of violet, indigo, blue and yellow light. Only the longer wavelengths of red and orange can get through to colour the sunset.