How many colors are there really in the rainbow???
(PhD physicist responds) The eye perceives six colors in the rainbow. Red, orange, yellow, green, blue and violet. (some people include the violet color of Indigo as a separate color.) But there are also colors in the infrared and ultraviolet present as well. The rainbow is caused by diffuse refraction of sunlight in water droplets. The source of the light is the sun’s photosphere. While each atom in the photosphere may emit light at one quantum frequency, the sun is so hot that doppler shifting of the light causes the lines to “fuzz out” so that you see essentially a continuous spectrum of light.
