The zodiacal light from 1.0 to 0.3 A.U. as observed by the HELIOS space probes

The average properties of zodiacal light are summarized as obtained from several years of observations from the Helios 1 and 2 space probes. Consistent results on intensity, color and polarization of the zodiacal light between 1.0 and 0.3 AU are obtained, and the intensity increase towards the sun as a function of heliocentric distance is found to be -2.3 + or - 0.05, where the upper and lower limits give the deviations observed at small and large elongations, respectively, from the sun. The polarization is higher than that found from ground-based observations, while decreasing towards 0.3 to about two-thirds of its value near the earth. Results are interpreted in terms of a spatial distribution of interplanetary dust, and the observed colors do not support a dominating abundance of submicron-sized particles.