Dancers at the Windmill Theatre in London, England practice a routine wearing gas masks and hard-hats with their costumes, 1940. (Photo by Hulton Archive/Getty Images)

Andrey Karr from Western Riders Slacklines at sunset above big waves in Nazare, Portugal on December 27, 2017. (Photo by Aidan Williams/National Geographic Travel Photographer of the Year Contest)

Sports Finalist – Ian MacNicol. Michalina Kwasniewska of Poland competes in the Women's high jump during day one of The European Athletics U23 Championships 2013 on July 11, 2013 in Tampere, Finland. (Photo by Ian MacNicol/Agence France-Presse)

This picture taken on December 15, 2019 shows three young orangutans after they were rescued by police from illegal wildlife traffickers in Pekanbaru in Riau province, Indonesia. (Photo by Wahyudi/Jefta Images/Barcroft Media)

A man and a woman take a selfie on Russian Navy Day in St Petersburg, Russia on July 26, 2020. (Photo by Roman Pimenov/TASS)

Canada's New Democratic Party (NDP) leader Jagmeet Singh meets with young adults outside Ryerson University during an election campaign stop in Toronto, Ontario, Canada on October 8, 2019. (Photo by Chris Helgren/Reuters)

Rockhopper penguins live up to their name as they navigate the rugged coastline of Marion Island in the southern Indian Ocean. (Photo by Thomas P. Peschak)

A dancer attends the final rehearsal for the new “VIVID Grand Show” at Friedrichstadt-Palast in Berlin, Germany, September 26, 2018. (Photo by Hannibal Hanschke/Reuters)