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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.icarus.2009.05.034 Byline: M.G. Tomasko, L.R. Doose, L.E. Dafoe, C. See Keywords: Titan Abstract: The Descent Imager/Spectral Radiometer (DISR) instrument on the Huygens probe into the atmosphere of Titan yielded information on the size, shape, optical properties, and vertical distribution of haze aerosols in the atmosphere of Titan [Tomasko, M.G., Doose, L., Engel, S., Dafoe, L.E., West, R., Lemmon, M., Karkoschka, E., 2008. Planet. Space Sci. 56, 669-707] from photometric and spectroscopic measurements of sunlight in Titan's atmosphere. This instrument also made measurements of the degree of linear polarization of sunlight in two spectral bands centered at 491 and 934nm. Here we present the calibration and reduction of the polarization measurements and compare the polarization observations to models using fractal aggregate particles which have different sizes for the small dimension (monomer size) of which the aggregates are composed. We find that the Titan aerosols produce very large polarizations perpendicular to the scattering plane for scattering near 90[degrees] scattering angle. The size of the monomers is tightly constrained by the measurements to a radius of 0.04[+ or -]0.01[mu]m at altitudes from 150km to the surface. The decrease in polarization with decreasing altitude observed in red and blue light is as expected by increasing dilution due to multiple scattering at decreasing altitudes. There is no indication of particles that produce small amounts of linear polarization at low altitudes. Author Affiliation: Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092, USA Article History: Received 3 September 2008; Revised 1 May 2009; Accepted 5 May 2009

Observations of one of Saturn's moons from the two Voyager probes and the Hubble Space Telescope (HST) were compared. The observations were analyzed and it has been concluded that the variations in brightness may be explained by the seasonal model implying seasonal changes in the atmosphere of Titan. The images from the HST were subjected to the Fourier deconvolution technique and the Lucy iterative method of image deconvolution in order to clarify the images.