Cassini's first radar image of Titan
is centered in the northern hemisphere of Titan, over a region that has not yet been imaged optically (50° N, 54° W). Mission scientists think brighter areas correspond to rougher terrain and that darker areas are smoother. The dark area in this view, The darker regions in this view, which the Cassini team nicknamed "Si-Si the Cat" when a team member's daughter pointed out its feline appearance, is consistent with a very smooth or highly absorbing solid, but could also be liquid.
NASA / JPL