Steam emerges from a cooling tower of the nuclear power plant Leibstadt near Leibstadt, Switzerland, November 18, 2014. (Photo by Arnd Wiegmann/Reuters)

Soldiers try to attach the balloon to their car, June 1944. (Photo by Jared Enos/Mediadrumworld.com)

A pilot inflates a hot air balloon while taking part in the 38th International Balloon Festival of Chateau-d'oex, Switzerland, 23 January 2016. The festival takes place from 23 to 31 January. (Photo by Vincent Vannay/EPA)

People look at a man, who residents said was killed by al Qaeda militants, hanging on a bridge in Yemen's southeastern city of Mukalla June 17, 2015. Al Qaeda militants in Yemen killed two alleged Saudi spies, residents said, accusing them of planting tracking devices which enabled the assassination of the group's leader in a suspected U.S. drone strike. (Photo by Reuters/Stringer)

The sun rises beside St Mary's Lighthouse in Whitley Bay, Tyne and Wear, as the unseasonably cool weather continues on Thursday, April 28, 2016. (Photo by Owen Humphreys/PA Wire)

Two sheep fight in a competition in Zhangjiakou, Hebei province, China on August 1, 2017. (Photo by Reuters/China Stringer Network)

A woman plays with her three dogs at the beach after sunset in Del Mar, California, USA on November 10, 2017. (Photo by Mike Blake/Reuters)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)