Sichuan Opera performer Wu Yonghong, 26 years, of the Jinyuan Opera Company performs for villagers at the Dongyue Temple on May 2, 2016 in Cangshan, Sichuan province, China. Sichuan opera is a vibrant, centuries-old tradition that showcases the joys and challenges of daily life in rural China with tales of love, tradition, and family honor. Photo by Kevin Frayer/Getty Images)

An Army Sikorsky R-5 helicopter, undergoing record trials, demonstrates its lifting power by carrying 17 persons and pilot aloft as female onlookers wave in Bridgeport, Conn., January 10, 1946. During the tests records were claimed for altitude speed and both altitude and speed with payload. (Photo by Anthony Camerano/AP Photo)

A bunker at aformer Swiss artillery fortress called Heldsberg stands near the town of St. Margareten, Switzerland March 22, 2015. Heldsberg fortress, located on the Swiss-Austrian border near the River Rhine and Lake Constance was built from 1938 to 1940 and remained in military use until 1992. Since 1993 it is open to the public as Fortress Museum Heldsberg. (Photo by Arnd Wiegmann/Reuters)

“People of the River”. This is a Karo tribe family; father, mother, two sisters and two brothers. The tribe, who live along the Omo River in east Africa, incorporate rich symbolism into their rituals by using ornate body art, headdresses and body scarification to express beauty and significance. (Photo by Jatenipat Ketpradit/International Portrait Photographer of the Year)

Underwater photographer of the year – winner. Dancing Octopus by Gabriel Barathieu (France). Location: Island of Mayotte, off the coast of south-east Africa. “Balletic and malevolent”, one judge said of this octopus, hunting in a lagoon. Barathieu waited until spring tides when there was just 30cm of water on the flats and plenty of light in the shallows. (Photo by Gabriel Barathieu/UPY2017)

Bao Bao, the Giant Panda cub is seen by the media for the first time January 6, 2014 inside his glass enclosure at the Smithsonian's National Zoo in Washington, DC, a few days before going on display to the general public. Bao Bao was born at the Smithsonian's National Zoo August 2, 2013. (Photo by Paul J. Richards/AFP Photo)

Lance Corpral Johnnie Miller of the Household Cavalry rehearses at Floors Castle in preparation for massed Pipe Band day on August 26, 2011 in Kelso, Scotland. The event, being held on August 28, will feature the first Scottish performance of the Household Cavalry's Musical ride in over 10 years. (Photo by Jeff J Mitchell/Getty Images)

Wrecked tanks are seen close to the road that leads to the village of Imber on December 31, 2011 on Salisbury Plain, England. (Photo by Matt Cardy/Getty Images)