Photoelectric Observations of the Zodiacal Light

Abstract

IT has been generally accepted that the zodiacal light comes from the scattering of solar light by dust-particles in the planetary system, which are concentrated towards the earth's orbital plane. On the other hand, it is known that the sun emits continuously a variable number of charged particles, principally protons and electrons. The possibility that the free electrons give some part of the luminosity of the zodiacal light has been discussed by F. L. Whipple aud J. L. Gossner¹, who derived maximum values of the possible electron densities in the space between sun and earth. For the following discussion of the density of electrons and dust particles in the planetary system we use the results of photoelectric registrations of brightness and polarization in the zodiacal light with a 1 P 21-multiplier. These were obtained during February/March and October 1952 and in the recent winter at the Hochalpine Forschungsstation Jungfraujoch (altitude 3,600 m.). Details of the apparatus and the observing and reduction methods are given in a paper by A. Behr and H. Siedentopf².