Pope Francis greets the crowd from his popemobile in downtown Rio de Janeiro. Pope Francis touched down in Rio de Janeiro on Monday, starting his first foreign trip as pontiff and a weeklong series of events expected to attract more than a million people to a gathering of young faithful in Brazil, home to the world's largest Roman Catholic population. (Photo by Ueslei Marcelino/Reuters)

Karis, a one month old lion cub being weighed at Blair Drummond Safari Park near Stirling, Scotland, Thursday October 10, 2013. Weighing in at 5kg, the cub will stay with her mother, Teekay until she is 12 weeks old before they are returned to the pride. (Photo by Andrew Milligan/AP Photo/PA Wire)

Members of an Orthodox community take part in an Easter service at a church in the village of Poteryaevka, some 200 km (124 miles) southwest of the city of Barnaul in Russia's Altai region, on April 24, 2011. (Reuters/Andrei Kasprishin)

A girl goes to school just before sunrise in Frankfurt, Germany, Wednesday, December 11, 2019. (Photo by Michael Probst/AP Photo)

Three white tigers cub born on January 05, 2020 stand beside their mother Orissa at the zoological park of Amneville, northeastern France, on March 9, 2020. (Photo by Jean-Christophe Verhaegen/AFP Photo)

Thierry Neuville of Belgium drives his Hyundai i20 Coupe WRC during day 3 of Rally Mexico, in Leon, Guanajuato, Mexico, 14 March​ 2020. (Photo by Reporter Images/EPA/EFE)

A dog wearing a mask is seen on a street following an outbreak of the novel coronavirus disease (COVID-19), in Shanghai, China on March 22, 2020. (Photo by Aly Song/Reuters)