Showing papers by "Richard M. Goldstein published in 1965"
TL;DR: Radar studies of Mars indicate that certain areas are quite smooth, while Mars as a whole is significantly smoother to radiation of 12.5-centimeter wavelength than Venus.
Abstract: Radar studies of Mars indicate that certain areas are quite smooth. Rough, strongly reflecting regions have also been found, as well as poorly reflecting ones. Mars as a whole is significantly smoother to radiation of 12.5-centimeter wavelength than Venus.
22 citations
TL;DR: In this article, the rotational period of all the planets in the solar system, even the most distant planet Pluto, with the exception of the planet that comes nearest to us, has been determined by observing the relative Doppler shift of the lines in its optical spectrum.
Abstract: The determination of the axial rotational rate of Venus has long been an objective of planetary astronomers. It may be surprising to learn that we know the rotational period of all the planets in the solar system, even the most distant planet Pluto, with the exception of the planet that comes nearest to us, Venus! This anomaly fundamentally arose for two reasons: (1) Venus is shrouded with a thick, almost featureless cloud cover that prevents us from seeing its surface; and (2) Venus rotates very slowly. If the surface could be seen, we could track the motion of various markings and thus determine the rotation; or if Venus' rotation were faster, we could observe the relative Doppler shift of the lines in its optical spectrum resulting from the difference in velocity between its approaching and receding limbs. We could then compute the period from this velocity. Unfortunately, Venus appears to rotate so slowly that the errors in the classical velocity measurements have been as great as the velocity actually measured.
5 citations