Also known as tholins
thumb|Neverland Regio, a dark region on Charon's north pole. The region is stained a dark brown by deposits of tholins Tholins (after the Greek ('''') "hazy" or "muddy"; from the ancient Greek word meaning "sepia ink") are a wide variety of organic compounds formed by solar ultraviolet or cosmic ray irradiation of simple carbon-containing compounds such as carbon dioxide (), methane () or ethane (), often in combination with nitrogen () or water (). Tholins are disordered polymer-like materials made of repeating chains of linked subunits and complex combinations of functional groups, typically