The icy region on Pluto, unofficially known as Sputnik Planum, is likely a large impact basin, say members of NASA’s New Horizons mission team in this abstract, presented at the 227th meeting of American Astronomical Society (AAS).

Sputnik Planum imaged by NASA’s New Horizon’s spacecraft. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute.

One of the most startling features seen on Pluto is a vast, nearly crater-free plain of oddly patterned nitrogen and methane ices. An eroded plateau to the northeast, and high peaks to the southwest with a different morphology suggest a massive irregularly shaped impact basin, similar to that of the Caloris Basin on Mercury.

Mercury’s Caloris Basin, One of the Largest Impact Basins in the Solar System. Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington.

After the impact on Pluto, the basin filled up with ices, eliminating any visual traces of former impact craters in the region. The lack of cratering, and evidence of glaciation show that Sputnik Planum is relatively young, and geologically active.