A sun bear reacts to triple-digit temperatures at the Henry Doorly Zoo in Omaha, Nebraska, where the temperature reached 103 degrees Fahrenheit on July 6, 2012. (Photo by Nati Harnik/Associated Press)

An Indian girl dressed in traditional attire reacts to camera as she watches a cultural performance during Lohri festival in Jammu, India, Monday, January 13, 2014. Lohri is a celebration of the winter solstice observed by Hindus and Sikhs in northern India. (Photo by Channi Anand/AP Photo)

Ireland's Philip Mulpeter, left, is kicked by Brazilian Vitor Nobrega during their welterweight mixed martial arts bout of International Pro Combat at the Estoril Casino in Estoril, near Lisbon, Portugal, Monday, January 26, 2015. Nobrega defeated Mulpeter. (Photo by Francisco Seco/AP Photo)

A vehicle leaves light trails in a long exposure photograph as it drives beneath the 500-metre Aperture Spherical Radio Telescope in Pingtang county, China. Construction on the device began in 2011 and is nearing completion. (Photo by Liu Xu/AP Photo)

A female sniper of the Syrian Democratic Forces (SDF) monitors the area during a celebration at the iconic Al- Naim square in Raqa on October 19, 2017, after retaking the city from Islamic State (IS) group fighters. The SDF fighters flushed jihadist holdouts from Raqa' s main hospital and municipal stadium, wrapping up a more than four- month offensive against what used to be the inner sanctum of IS' s self- proclaimed “caliphate”. (Photo by Bulent Kilic/AFP Photo)

Women jump into the water during a traditional New Year bath in the Adriatic sea in Portoroz, Slovenia on January 1, 2018. (Photo by Jure Makovec/AFP Photo)

Leslie Cliff and his wife Violet, English figure skating pair. Olympic games of Garmisch-Partenkirchen (Germany), 1936. (Photo by Roger Viollet Collection/Getty Images)