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BBC: Among the features on Pluto’s surface is a large, 900 000 km2 basin that is filled with nitrogen ice mixed with small amounts of methane and carbon monoxide. The basin's surface is divided into irregular, domed polygons some 20–30 km in diameter and separated by troughs as deep as 100 m. Called Sputnik Planum, the spectacular icy plain was discovered by the New Horizons spacecraft when it flew past Pluto in 2015. According to two recent studies, the feature is geologically young—just 1 million years old—and active: Heat from the dwarf planet’s interior drives thermal convection in the nitrogen ice, whose churning and roiling cause the surface to shift horizontally a few centimeters per year. Its size and high albedo make Sputnik Planum one of Pluto’s most prominent features.
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Expansive, icy plain on Pluto exhibits unusual geologic activity Free
2 June 2016