In a recent update Nasa's New Horizons spacecraft has captured images of frozen nitrogen glaciers on Pluto carrying numerous 'floating' hills that may be fragments of water ice. These hills individually measure one to several kilometres across. The hills, which are in the vast ice plain informally named Sputnik Planum within Pluto's 'heart,' are likely miniature versions of the larger, jumbled mountains on Sputnik Planum's western border..