In this timed-exposure night photo taken early on February 12, 2017, Mount Sinabung volcano spews reddish smoke and ash, as seen from the Karo district in North Sumatra province. Activity levels have increased in the past week, with Sinabung shooting hot ash clouds into the sky dozens of times, according to the local volcano monitoring agency. (Photo by AFP Photo/Stringer)

A giant Iron Man statue stands next to a replica Sphinx in Chuzhou, Anhui Province, China on February 21, 2017. (Photo by Sipa Asia/Rex Features/Shutterstock)

A woman holds an elderly woman on her back to cross a flooded street after a heavy rain in Shenyang, Liaoning province on July 14, 2017. (Photo by Fred Dufour/AFP Photo)

New York City policemen tangled with demonstrators at a subway station on the opening day of the New York World's Fair, April 22, 1964. Youths attempted to stall the train, which was headed from the city to the fairgrounds, as a form of protest on behalf of civil rights for blacks. (Photo by Charles Gorry/AP Photo)

Libya's leader Muammar Gaddafi attends a meeting with Italian President Giorgio Napolitano at the Quirinale Palace on June 10, 2009 in Rome, Italy. Colonel Gaddafi is in Rome to attend a meeting of G8 Development Ministers. (Photo by Franco Origlia/Getty Images). ROME – JUNE 10

Three workers demonstrating the different types of gas masks used in mine rescue work. (Photo by Fox Photos/Getty Images). December 1925

Film actress Audrey Hepburn (1929–1993) on a film set with her pet poodle, circa 1960. (Photo by Hulton Archive/Getty Images)