Observations of the Polarization of the Night Sky and a Model of the Zodiacal Cloud Normal to the Eliptical Plane

From observations of the surface brightness and polarization of the night sky in high ecliptic latitudes the brightness of the polarized component of the zodiacal light is deduced on the assumption that the airglow and the integrated starlight are both unpolarized. A model of the zodiacal cloud in which the relative particle density normal to the ecliptic plane is given by ρ = exp (− tan γ), where γ is the heliocentric latitude, is found to fit the brightness measurements of Smith, Roach & Owen (14) for values of $\lambda-\lambda_\odot\geqslant90^\circ$ and to be in general accord with the present observations. Recent measurements of the brightness and degree of polarization of the zodiacal light at the North Ecliptic Pole are discussed critically.