Infrared Titan (from approx. 1,2 MKM)

Caption NASA originale:"Southeast of Xanadu (and above the center in this view) is a peculiar semi-circular feature informally referred to by imaging scientists as "The Smile". This surface feature is the brightest spot on Titan's surface, not only to the Imaging Science Subsystem Cameras, but also to the Visual and Infrared Mapping Spectrometer (VIMS), which sees the surface at even longer wavelengths. "The Smile" is about 560 Km (345 miles) wide.
At the landing site of the successful Huygens probe mission, brighter regions correspond to icy upland areas, while the darker regions are lowlands that possess a higher proportion of the organic byproducts of Titan's atmospheric photochemistry. Those results seem to confirm the long-standing hypothesis that Xanadu is a relatively high region of less contaminated ice. However, the cause of the even brighter Smile is a mystery that is still under study. Farther South, a field of bright clouds arcs around the Pole, moving at a few meters per second".