Accession Number:

AD0617037

Title:

POLARIZATION OF THERMAL EMISSION FROM VENUS.

Descriptive Note:

Revised ed.,

Corporate Author:

HARVARD COLL OBSERVATORY CAMBRIDGE MASS

Personal Author(s):

Report Date:

1964-11-07

Pagination or Media Count:

23.0

Abstract:

Thermal emission from a specific locale on a planetary surface is, in general, polarized, because the emissivities parallel 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, epsilon. Illustrative calculations indicate that the integrated polarization of the 3-cm radiation from Venus is probably between 0.35 and 2 per cent, which is 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 epsilon 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 approximately 400 K. An analysis is made of the incomplete set of interferometric observations of Venus obtained at Owens Valley Radio Observatory by Clark and Spencer. These observations are shown to be consistent with the radar reflectivity and microwave phase effect of Venus if the surface temperature varies markedly approximately 500 K between the subsolar point and the pole. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE