Mercury's Perihelion Progress

Abstract

IF Mercury sweeps up solar matter in its course round the sun—such matter as yields the Zodiacal light, for example—there will be no effect on its transverse or centripetal acceleration, but it will experience, tangential retardation. This, if uniform, so that m= a + bθ, would give a spiral character to the orbit; but if the sweeping up were periodic, with the planet's period, the orbit would suffer cumulative perturbations of the ordinary de and edω type.