Data collected by NASA's New Horizons probe during its Pluto fly-by last year has revealed just how geologically active Pluto is, and that its moon Charon was once active but is now dead.

Jeffrey Moore at the NASA Ames Research Center in Moffett Field, California, and his team report a huge 870,000-km2 basin on Pluto's surface that contains moving ice layers. It is about 10 million years old at most, and is probably still active. Ancient craters elsewhere on Pluto seem to be up to 4 billion years old and show evidence of tectonics and glacial flow. By contrast, Charon is not active, although it seems to have experienced heavy volcanic activity around 4 billion years ago.

In another paper, William Grundy at the Lowell Observatory in Flagstaff, Arizona, and his team report that methane, carbon monoxide and nitrogen ices are sublimating, condensing and flowing on the surface of Pluto.

Science http://doi.org/bdg8; http://doi.org/bdg9 (2016)