Katie Rose Hobbs and Kirsten Elizabeth Pobjoy of British Aerosuperbatics Wingwalking Team perform ballet in the air during Huangguoshu Waterfalls Flight Conference on August 3, 2018 in Anshun, Guizhou Province of China. Huangguoshu Waterfalls Flight Conference including 18 aircraft from seven aerobatic teams from all over the world kicked off on Friday. (Photo by VCG via Getty Images)

Cooler temperatures begin this week as a polar vortex brings much colder conditions with the chance of snow for Snowdonia, Ogwen Valley, North Wales on 22nd October 2018. The Ogwen Valley and Tryfan Mountain looking splendid in the Autumn sunrise. (Photo by DGDImages/Alamy Live News)

A German rifleman beside the corpse of a French soldier in a trench at Fort Vaux, France, 1916. (Photo by Hulton Archive/Getty Images)

European bisons (also known as Wisent) at the Bison farm in Muczne, southeastern Poland, 30 December 2018. The Bison farm is a continuation of bison breeding in Bieszczady, which was started in 1963. Here visitors can admire the bison of Bialowieza-Caucasian line, also called the mountain race. The European Bison is the national animal of Poland. (Photo by Darek Delmanowicz/EPA/EFE)

This undated handout photograph released by Stony Brook University/ Louisiana State University on March 2, 2018, shows an Adélie penguin looking at a drone at breeding colony on Heroina Island, Danger Islands, Antarctica. A thriving “hotspot” of some 1.5 million Adelie penguins has been discovered on the remote Danger Islands in the east Antarctic, surprised scientists announced on March 2, 2018. (Photo by Rachael Herman/AFP Photo/Louisiana State University AND Stony Brook University)

Myanmar national award second-place winner: Kyaw Win Hlaing. “Mount Bromo is an active volcano in East Java, Indonesia. The name Bromo derives from the Javanese pronunciation of Brahma, the Hindu creator god”. (Photo by Kyaw Win Hlaing/Sony World Photography Awards 2018)

Members of the Mayossa Folk Dance Group pour water on young women in Kiskunmajsa, some 140 kms southeast of Budapest, Hungary, Monday, April 2, 2018. According to a several hundred years old tradition of Hungarian villages young men pour water on young women who in exchange present their sprinklers with beautifully colored eggs on Easter Monday. (Photo by Sandor Ujvari/MTI via AP Photo)

A Pakistani vendor tries to salvage materials after flood water destroyed his shop following heavy rain on the outskirts of Peshawar on April 4, 2016. (Photo by A. Majeed/AFP Photo)