Studies in Astronomical Polarimetry: III. The Wavelength Dependence of the Polarization of Light Reflected by the Moon and Mars

Previous polarization measurements of the light reflected by the Moon have been collected and discussed. Some new observations have been made by the author including measurements of the wavelength dependence of the polarization. There is evidence that about two days before full moon, the direction of the vibration of the polarization rotates through 90°. This rotation is apparent first in the red and progresses through the spectrum to the blue. A similar rotation effect occurs with Mars and this has been studied more closely because of the slower rate of change of phase angle with time. This effect had not previously been observed for Mars and only observed in white light for the Moon. A method of using the wavelength dependence of polarization to obtain values of lunar albedo at different wavelengths is also discussed. When the lunar polarization is high, its wavelength dependence could lead to the detection of lunar luminescence bands.