The Northern Lights glow green in a spectacular light show above a field of trees frozen solid with snow. (Photo by Jaak Sarv/Solent News & Photo Agency)

A man wearing a mask and dressed in a clown costume rides an electric tricycle while carrying a container in the shape of a rubber duck amid heavy smog in Beijing, China, December 29, 2015. (Photo by Jason Lee/Reuters)

A demonstrator is carried during a rally in support of a identity check draft law and against delinquency, in Santiago, Chile April 30, 2016. (Photo by Carlos Vera/Reuters)

A kite flying contest is held in Nantong, east China's Jiangsu featuring various kites of different shapes on December 20, 2017. (Photo by SIPA Asia/Pacific Press/Barcroft Images)

A Palestinian woman takes a picture of a member of the Israeli security forces as he takes her picture in a street in Jerusalem on December 16, 2017, as demonstrations continue to flare in the Middle East and elsewhere over the US president' s declaration of Jerusalem as Israel' s capital. (Photo by Ahmad Gharabli/AFP Photo)

The New World porcupine, family Erethizontidae, 1280 Gram born at 11 April 2015 Inventory in Zoo. Counting trade Fairs Weighing the Zoo is at 7 May 2015 too the 108 Birthday Zoo Hagenbeck Hamburg, Germany. (Photo by Imago/ZUMA Wire)

U.S. players push head coach Adam Krikorian into the pool after they defeated the Netherlands in their women's water polo gold medal match during the Aquatics World Championships in Kazan, Russia, August 7, 2015. (Photo by Michael Dalder/Reuters)

A remote-controlled plane in the form of a witch flies over a neighborhood as the sun sets during Halloween in Encinitas, California, U.S. October 31, 2016. (Photo by Mike Blake/Reuters)