Tethys' transition (false colors)

Caption NASA originale:"An extreme false-color view of Tethys reveals a surface detail not visible in a monochrome view taken at the same time. The false-color view shows a color transition from the moon's Saturn-facing side (left) to a region its trailing side (bottom).
Near the top of the images, the central-peaked crater Telemachus lies in the deeply grooved terrain that marks the northern reaches of Ithaca Chasma.

To create the false-color view, ultraviolet, green and infrared images were combined into a single picture that isolates and maps regional color differences. This "color map" was then superposed over a clear-filter image that preserves the relative brightness across the body.
The combination of color map and brightness image shows how colors vary across Tethys' surface. The origin of the color differences is not yet understood, but may be caused by subtle differences in the surface composition or the sizes of grains making up the icy surface material".