Children in Hiroshima, Japan, wearing masks to combat the odour of death after the city was destroyed by the first atom bomb. (Photo by Keystone/Getty Images). 1945

Brick-carving featuring Tang Dynasty (AD 618-907) maids performing musical instruments is seen at the Chinese Music History Museum in Xian University of Architecture and Technology on September 27, 2008 in Xian of Shaanxi Province, China. (Photo by China Photos/Getty Images)

U.S. Rep Steve Southerland grins after winning an auctioned possum during the Wausau Possum Festival on Saturday, August 2, 2014, in Wausau, Fla. What is usually a must-attend event for statewide candidates was notably lacking of them this year, perhaps because candidates who now raise tens of millions of dollars focus more on television ads than making personal contact. But not attending is a missed opportunity, said Susan MacManus, a University of South Florida political science professor who drove more than 350 miles for the festival. (Photo by Heather Leiphart/AP Photo/The News Herald)

A man pulls a cart with collapsed cardboard boxes past boutiques in the Sinchon district in Seoul, May 5, 2015. (Photo by Thomas Peter/Reuters)

Children of local herders gather at a reindeer camping ground, some 200 km (124 miles) northeast of Naryan-Mar, the administrative centre of Nenets Autonomous Area, far northern Russia, August 2, 2015. People, including local herders and members of their families, gathered at the site to mark Reindeer Day, a professional holiday of reindeer breeding workers, which is celebrated annually on August 2 in the region. (Photo by Sergei Karpukhin/Reuters)

A journalist operate a harness with multiple recording devices capable of recording and live streaming outside the Great Hall of the People where the opening session of the Chinese People's Political Consultative Conference (CPPCC) was held in Beijing, China, Friday, March 3, 2017. Thousands of delegates have gathered at the Chinese capital for the opening of the annual session of the Chinese People's Political Consultative Conference, which advises the rubberstamp parliament, whose annual session begins Sunday. (Photo by Ng Han Guan/AP Photo)

The possible surface of TRAPPIST-1f, one of seven newly discovered planets in the TRAPPIST-1 system that scientists using the Spitzer Space Telescope and ground based telescopes have discovered. (Photo by Reuters/NASA/JPL-Caltech)

South Korea's Lee Dae-ho is hit by a pitch off Taiwan's pitcher Pan Wei-lun during the second inning of their first round game of the World Baseball Classic at Gocheok Sky Dome in Seoul, South Korea, Thursday, March 9, 2017. (Photo by Ahn Young-joon/AP Photo)