The white light that is produced by the sun is a blend on all the colors on the rainbow. This was shown by Isaac Newton who made use of a prism to distinguish different colors and thus result in a spectrum. The light colors are separated using the differing wave lengths. The part of the spectrum that can be seen ranges from light which is red in color that has a wavelength of approximately 720nm to violet light that has a wavelength of approximately 380nm having indigo, blue, green, yellow and orange in the middle. The three distinguishing kinds of color receptors found in the human eye retina respond with much strength to blue, green and red wavelengths providing us with the color vision.When transmitted light such as sunlight enters our atmosphere it collides with the oxygen and nitrogen atoms. The color with the shorter wavelength is scattered more by this collision. Because violet and blue are the shortest wavelengths the sky appears to be violet / blue. But because our eyes are more sensitive to blue light than they are violet light, we perceive the sky as blue. Our eyes contain thousand of rods and cones, which are the receptors for light. Whenever one of the 3 Stooges pokes you in the eye you see a giant blue spot.