Scientists have long debated whether a massive impact caused an Ice Age climate swing. Recently researchers discovered a crater buried beneath Greenland that may be the smoking gun for the theory. This image shows the topography under the site at Hiawatha glacier, mapped with airborne radar data (1997 to 2014, NASA; 2016 Alfred Wegener Institute). Black triangles and purple circles are elevated peaks around the rim and center. Dotted red lines and black circles show locations of additional sampling.