Across the Arctic, people have revered—and sometimes feared—eerie, shifting lights that arrived without warning in the night sky and never appeared the same way twice. Ancient explanations for the lights vary widely among the Saami, Tlingit, Vikings, and other northern cultures, changing from one fjord to the next and over centuries. The aurora borealis, or northern lights, have been described as the spirits of women who never married or of the stillborn; as restless, lonely souls of those who died from suicide or murder; as reflections glinting off the armor…