Reorientation and faulting of Pluto due to volatile loading within Sputnik Planitia.

Pluto is an astoundingly diverse, geologically dynamic world. The dominant feature is Sputnik Planitia-a tear-drop-shaped topographic depression approximately 1,000 kilometres in diameter possibly representing an ancient impact basin. The interior of Sputnik Planitia is characterized by a smooth, craterless plain three to four kilometres beneath the surrounding rugged uplands, and represents the surface of a massive unit of actively convecting volatile ices (N, CH and CO) several kilometres thick.