Source: Voyager 2

Information: Voyager 2 obtained this high-resolution color image of Neptune's large satellite Triton during its close flyby on August 25, 1989. Approximately a dozen individual images were combined to produce this comprehensive view of the Neptune-facing hemisphere of Triton. Fine detail is provided by high-resolution, clear filter images, with color information added from lower-resolution frames. The large south polar cap at the bottom of the image is highly reflective and slightly pink in color; it may consist of a slowly evaporating layer of nitrogen ice deposited during the previous winter. From the ragged edge of the polar cap northward the satellite's face is generally darker and redder in color. This coloring may be produced by the action of ultraviolet light and magnetospheric radiation upon methane in the atmosphere and surface. Running across this darker region, approximately parallel to the edge of the polar cap, is a band of brighter white material that is almost bluish in color. The underlying topography in this bright band is similar, however to that in the darker, redder regions surrounding it.