Figure 7-16 RIVUXG Triton Several high-resolution Voyager 2 images were combined to create this mosaic. The pinkish material surrounding Triton’s south polar region is probably nitrogen frost. Some of this presumably evaporates when summer comes to the south pole; the northward flow of the evaporated gas may cause the dark surface markings. Farther north is a brown area of “cantaloupe terrain” that resembles the skin of a melon.