According to the researchers behind the detection, the liquid nitrogen evidence captured by NASA’s New Horizons Spacecraft is the first evidence of any liquid flowing on Pluto. The researchers focused on the Greenland Ice Sheet, since similar surface features caused by liquid water separating ice and snow have been previously observed. As a result, the dark, thin surface features must have formed during that short window of time. According to the study authors, the models “show that nitrogen ice at the base of Pluto’s kilometers-deep Sputnik glacier can melt, forming liquid nitrogen.” “In addition to suggesting that liquids have recently expressed themselves on Pluto’s surface, it also suggests a new kind of time-variable feature on Pluto.”