76667
A couple of posts back buuut.
"Sunlight travels through the solar system in straight, invisible waves. This "white" light is a mixture of all the colours -- red, orange, yellow, green, blue indigo and violet -- in the visible portion of the electromagnetic radiation spectrum. Each colour of the visible spectrum travels at a different wavelength: red and orange have the longest wavelengths, while indigo and violet have the shortest. When the sunlight hits the atmosphere, the light waves are scattered in different directions by dust particles and air molecules. The shorter violet and blue waves are scattered more effectively than the longer orange and red ones. The effect is similar to what happens when ripples in water encounter a swimmer: small ripples are deflected while large waves continue past the obstacle undisturbed. A mixture of violet, blue, green and tiny amounts of the other colours are scattered across the sky. The combination of these colours are blue. The exact shade of blue will vary according to the amount of dust and water vapour in the air. Water droplets and dust particles enhance scattering, increasing the amount of green and yellow and turning the sky a paler blue."
THAT IS WHY THE SKY IS BLUE.