Etude Theorique de la Repartition de Luminance Sur le Disque de Venus

Abstract

The analysis of the sunlight scattered by Venus gives some insight upon its clouds. The measurements of polarized light are probably more sensitive to the nature of their constituents, and some recent studies seem to be able to give a satisfactory interpretation of this part of the scattered light. But the polarized light concerns the upper part of the clouds, and it is interesting to compare these results with intensity measurements. The phase curves, for the integrated light, leave some indeterminations, so we have studied if the intensity distribution on the Venus disk could give more accurate informations. This work, based on some plates kindly communicated by A. Dollfus, and analysed at Meudon Observatory, is more a preliminary investigation of the sensitivity of the method than an interpretation of the partial results presented. A simple model, of homogeneous plane parallel cloud, has been used, and the influence of various parameters has been tested (single scattering albedo, refractive index of particles and size distribution, optical depth of the cloud).