Dan Copeland, left, and Alex Morneau of Biddeford, Maine, former high school cheerleaders, perform back flips while enjoying the record breaking heat, Thursday, May 18, 2017, at Old Orchard Beach, Maine. The temperature climbed well into the 90s in many locations throughout the state. (Photo by Robert F. Bukaty/AP Photo)

A Raramuris indigenous woman takes part in the “Ultra maraton de los Canones 2017” (Ultra marathon of the Canyons), at La Sinforosa Canyon, in Guachochi, Chihuahua state, Mexico on July 15, 2017. More than 600 participants from different countries take part in the 63 and 100 kilometers races, along the Tarahumara mountain range. (Photo by Herika Martinez/AFP Photo)

The northern lights, or aurora borealis, appear in the sky over the Bamburgh lighthouse at Stag Rock in Northumberland, England on September 28, 2016. (Photo by Owen Humphreys/PA Wire via ZUMA Press)

Students walk to school on the first day of their new school year in Giza, south of Cairo, Egypt September 25, 2016. (Photo by Mohamed Abd El Ghany/Reuters)

Mel Harris shouts whilst a pick up truck belches smoke on the final night of the Deni Ute Muster in Deniliquin, New South Wales, Australia, October 1, 2016. In the small rural town of Deniliquin, on the edge of Australia's vast outback, around 20,000 “ute” lovers gathered in the mud to champion a national treasure deemed surplus to requirements by the big car manufacturers. (Photo by Jason Reed/Reuters)

A Lebanese man is reflected in a pool of dirty water as he casts his fishing pole from a rocky coastal area along the Beirut coastline, Lebanon, Monday, October 3, 2016. (Photo by Hassan Ammar/AP Photo)

A police officer detains a woman on suspicion of collaborating with the 18th street gang during a "Safe House" operation at the Concepcion neighbourhood in San Salvador, July 2, 2015. Salvadoran police make “Safe House” operations at dangerous neighbourhoods of the capital to prevent murders, according to local media. (Photo by Jose Cabezas/Reuters)

Boys play with water as they celebrate Myanmar's New Year Water Festival of Thingyan in Yangon, April 13, 2016. (Photo by Soe Zeya Tun/Reuters)