[VIDEO] RAYLEIGH SCATTERING explained by Professor Emeritus Walter Lewin at MIT (and more) For The Love Of Physics. I recommend watching the whole lecture from beginning, the part on color starts at about 28:00 http://youtu.be/SRh75B5iotI?t=27m56s
Blue Sky and Rayleigh Scattering
Rayleigh Scattering in the atmosphere - why the sky is blue
This is a deep image of the Sword of Orion - the three stars that make up the weapon hanging off the belt of this famous celestial hunter. The image showcases the amazing mix of physical and optical processes including atomic emission, Rayleigh scattering, reflection and absorbtion of light, that go on in this star forming region to create this kaleidescope of colours and details.