Pluto's heart is erasing its own history, its nitrogen plains so geologically restless that they shed impact scars faster than they accumulate them.
The bright plain on the image-left side of Pluto’s heart is Sputnik Planitia, a basin roughly 1,000 kilometres across filled mainly with nitrogen ice. Across all of the terrain New Horizons could inspect, no impact crater has been confirmed within it... [5800 chars]