Sputnik Planum
A vast, icy plain on Pluto's surface, informally named after Earth's first artificial satellite, Sputnik. Characterized by its smooth, craterless terrain, it is believed to be composed primarily of nitrogen ice and exhibits signs of recent geological activity.
Source: nasa.gov
APODs including "Sputnik Planum"
A Plutonian Landscape
15/05/2025
This shadowy landscape of majestic mountains and icy plains stretches toward the horizon on a small, distant world. It was captured from a range of about 18,000 kilometers when New Horizons looked back toward Pluto, 15 minutes after the spacecraft's closest approach on July 14, 2015. The dramatic, low-angle, near-twilight scene follows rugged mountains formally known as Norgay Montes from foreground left, and Hillary Montes along the horizon, giving way to smooth Sputnik Planum at right. Layers of Pluto's tenuous atmosphere are also revealed in the backlit view. With a strangely familiar appearance, the frigid terrain likely includes ices of nitrogen and carbon monoxide with water-ice mountains rising up to 3,500 meters (11,000 feet). That's comparable in height to the majestic mountains of planet Earth. The Plutonian landscape is 380 kilometers (230 miles) across.