Londoners sleep on the platform and on the train tracks at Aldwych Underground station,London, during heavy all night Nazi bombing raids, October 8, 1940. (Photo by AP Photo)

A zoo employee carries three-month-old female giant panda cub, born to mother Liang Liang and father Xing Xing, on display to the public for the first time at the national zoo in Kuala Lumpur, Malaysia, November 17, 2015. (Photo by Olivia Harris/Reuters)

Visitors wear shirts with an image of former Chinese leader Mao Zedong at the Shanghai World Expo site in Shanghai, May 2, 2010. (Photo by Aly Song/Reuters)

The 30th anniversary of the meltdown at the Chernobyl nuclear plant that caused large amounts of radioactive particles to be released into the air will be commemorated on April 26, 2016. Photojournalist Sean Gallup returned to the area to document the lasting effects of the world's worst nuclear power plant accident. Pictured, children's beds are seen in an abandoned kindergarten in Kopachi village located inside the Chernobyl exclusion zone, September 29, 2015, near Chernobyl, Ukraine. (Photo by Sean Gallup/Getty Images)

A fire engine drives away from flames on the ridge, east of Silverwood Lake in Crestline, Calif., Sunday, August 7, 2016. (Photo by Terry Peirson/The Press-Enterprise via AP Photo)

Libyan forces allied with the U.N.-backed government fire a shell at Islamic State fighters' positions in Sirte, Libya August 15, 2016. (Photo by Ismail Zitouny/Reuters)

A girl struggles with winds from approaching Typhoon Matmo along the eastern coast of Keelung, northeastern Taiwan, Tuesday, July 22, 2014. (Photo by Wally Santana/AP Photo)

Old Heidelberg, Dog with Pipe, 1905. (Photo by Detroit Publishing Company)