Polarization of Thermal Emission from Venus.

Abstract

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Polarization of Thermal Emission from Venus. Pollack, J. B. ; Sagan, C. Abstract Thermal emission from a specific locale on a planetary surface is, in general, polarized, because the emissivities parallel to and perpendicular to the plane of incidence are unequal. A radio telescope unable to resolve the planet will observe a net polarization in the thermal emission for appropriate asymmetries in the surface distribution of temperature T or dielectric constant ~. Illustrative calculations indicate that the integrated polarization of the 3-cm radiation from Venus is probably between 0.35% and 2%, which s close to or slightly below the capability of existing radio telescopes. A possibly more promising method of determining the polarization of Venus radio emission is provided by interferometry. Under certain, probably valid, approximations, a complete set of observations with one-dimensional resolution across the planetary disk can obtain the two-dimensional distribution of E and T across the disk, and the obliquity of the axis of rotation. The observed integrated brightness temperature phase effect requires a surface temperature difference between subsolar and antisolar point 400 K0. An analysis is made of the incomplete set of interferometric observations of Venus obtained at Owens Valley Radio Observatory by Clark and Spencer (1963). These observations are shown to be consistent with the radar reflectivity and microwave phase effect of Venus if the surface temperature varies markedly (=500 K0) between the subsolar point and the pole. Publication: The Astronomical Journal Pub Date: 1965 DOI: 10.1086/109586 Bibcode: 1965AJ.....70R.146P full text sources ADS |