The sky is an unobstructed view upward from the surface of the Earth.The colors we see in the sky come from sunlight that is scattered by molecules in the atmosohere.This process is called Rayleigh scattering. Nitrogen and oxygen make up most of the molecules in our atmosphere, but any gas or aerosol suspended in the air will scatter rays of sunlight into separate wavelengths of light.The different combinations of red,yellow and orange light rays emitting from the sun cause the different colours of the sky.