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Surface features

All detailed knowledge of the surface of Triton was acquired from a distance of 40,000 km by the Voyager 2 spacecraft during a single encounter in 1989. The 40% of Triton's surface imaged by Voyager 2 revealed blocky outcrops, ridges, troughs, furrows, hollows, plateaus, icy plains and a few craters. Triton is relatively flat; its observed topography never varies beyond a kilometer. The impact craters observed are concentrated almost entirely in Triton's leading hemisphere. Analysis of crater density and distribution has suggested that in geological terms, Triton's surface is extremely young, with regions varying from an estimated 50 million years old to just an estimated 6 million years old. Fifty-five percent of Triton's surface is covered with frozen nitrogen, with water ice comprising 15–35% and frozen CO forming the remaining 10–20%. The surface also has deposits of tholins, a dark, tarry slurry of various organic chemical compounds.