Ever wonder why the sky is blue? The answer links the air we breath and the rainbow created by a prism splitting sunlight. The atmosphere is largely made up of two colorless gases: oxygen and nitrogen. Sunlight appears white but is made up of a rainbow of colors created by light with different wavelengths. Because the wavelength of blue light is roughly the size of an atom of oxygen, blue light interacts with the oxygen in the atmosphere and is scattered by it. If the Earth had no atmosphere, the sun’s light would travel directly from the Sun in a straight line towards our eyes and we would see the Sun as a very bright star in sea of blackness. Because the blue light waves in sunlight are scattered by the oxygen in the atmosphere, blue light from the Sun enters our eyes from all sorts of different angles and we see the entire sky as blue.