Caption: 
NASA's New Horizons spacecraft captured this image of Sputnik Planitia — a glacial expanse rich in nitrogen, carbon monoxide and methane ices — that forms the left lobe of a heart-shaped feature on Pluto’s surface. SwRI scientists studied the dwarf planet’s nitrogen and carbon monoxide composition to develop a new theory for its formation. 

Credit: 
Image Courtesy of NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute