Fig. 4. At high noon, sunlight (a collection of all the colors) strikes the atmosphere in a perpendicular fashion. Note: blue is scattered to a far greater extent than green, which is scattered more than red. At sunset (left), the sun's rays travel a longer distance through the atmosphere. The sun's rays encounter more atmospheric particles; thus, after much of the blue has been scattered away, more of the green gets scattered. The result is a redder sun at sunset.