Researchers from the Southwest Research Institute in the USA have put forward an exciting theory in the journal Icarus. The scientists have tried to assemble a model for the formation of the dwarf planet Pluto. Here they have looked in particular at the nitrogen-rich Sputnik Planitia basin that is covered by a gigantic glacier made from frozen nitrogen. They combined this data with results from the Rosetta probe that studied the comet 67P. Their findings: the nitrogen content fits well with the theory that Pluto is a conglomeration of approximately one billion (!) comets or other similar Kuiper Belt…