Here are 5 of the weirdest auroras, including the newly spotted ‘dunes’
Sky watchers have spotted a new jewel in the crown of northern lights that shimmer over the top of the world. The new kind of spectacle is a rare, faint phenomenon dubbed the “dunes.” Unlike other auroras that hang in the sky like luminous curtains, the dunes appear as green bands running parallel to the ground and pointing toward the equator, researchers report online January 28 in AGU Advances. Using photographs snapped from different locations across Finland in October 2018, researchers triangulated the position of a set of the dunes stretching from western Sweden to western Finland, and hovering about 100 kilometers above the ground. “Aurorae are like fingerprints in the sky,” says study coauthor Minna Palmroth, a space physicist at the University of Helsinki. Broadly speaking, auroras — often called northern lights or southern lights — appear when electrons from the magnetic bubble, or magnetosphere, surrounding Earth rain into the atmosphere and set oxygen and nitrogen gas aglow (SN: 7/25/14). But the particulars of those particle interactions...