Photograph by Chris McGrath—Getty ImagesA boy tends to a candlelit paper lantern near the Atomic Bomb Dome in Hiroshima, Japan, on Aug. 6, to mark the 70th anniversary of the World War II--ending bombings of Hiroshima and Nagasaki. Pope Francis later called the blasts a  lasting warning to humanity  to ban nuclear weapons. (TIME issue August 24, 2015)