Abstract

Observations of the clear sky’s polarization have a venerable history that includes such 19th-century figures as David Brewster, Jacques Babinet, and François Arago. In his pivotal 1871 paper on sky color and polarization, Lord Rayleigh provided a succinct theoretical explanation for skylight’s maximum polarization 90° from the sun. Rayleigh did not mention the neutral points (points of zero polarization) observed in the sun-zenith plane by Arago, Babinet, and Brewster. Although Rayleigh was confident that he had “disposed of the polarization” problem (Strutt 1871, p. 110), others did not view his silence on the neutral points as a proscription.

© 1997 Optical Society of America