This image of a sand dune field in a Southern highlands crater was acquired when the Sun was just 5 degrees above the horizon. As a result, the image is mostly shadows, with sharply-delineated dune crests sticking up into the sunlight.
The especially bright patches— bluish in enhanced color —are due to seasonal frost that is accumulating as this hemisphere approaches winter.
Written by: Alfred McEwen (audio: Tre Gibbs) (12 March 2014)
More info and image formats at http://hirise.lpl.arizona.edu/ESP_035143_1325
Image: NASA/JPL/University of Arizona