Excerpts from an article by Wilfried Heller ^[1]

In 1870 and 1871 the Franco-Prussian war was raging on the continent of Europe and many Englishmen were deeply concerned about the effect of the outcome on the continental balance of power. One Englishman, J.W. Strutt, however, was concerned about an entirely different matter. He was wondering why the sky is blue during the day since in absence of any reflecting matter in the atmosphere one would have expected it to be pitch black. While Wilhelm I and Napoleon III tried to make politcal history, Mr. Strutt made real history by developing a theory intended to solve the mystery of the sky's coloration. Now, more than 120 years later, one realizes how tremendously a breakthrough Strutt's theory represented. It is to the credit of Queen Victoria that, here again, she proved to be very farsighted because Mr. Strutt was soon to be knighted, i.e., he was allowed, in 1873, to assume the title of his father, Lord Rayleigh.

Rayleigh had postulated a new phenomenon in order to account for the blue of the sky: light scattering. He assumed that the individual molecules in the atmosphere on being illuminated by the sun, scatter in all directions a minute fraction of the radiation received. Assuming that each molecule behaves, under the influence of incident radiation, like a single induced dipole, he calculated the nature of the effect to be expected and found it to be essentially in agreement with the facts. According to his...