Polar bear twins make their first public appearance with their mother “Freedom” at Ouwehands Zoo Rhenen, in Rhenen, The Netherlands, 19 February 2015. The twins, who were born in November 2014, have not been named because their gender has not yet been determined. (Photo by Bart Maat/EPA)

A hot air balloon flies close to the ground in the Jezreel Valley in northern Israel during an international hot air balloon festival October 14, 2014. (Photo by Nir Elias/Reuters)

Refugees and migrants try to find a place on an already full train headed for Serbia, near the city of Gevgelija, The Former Yugoslav Republic of Macedonia, on February 24, 2016. Refugees and migrants from Iraq and Syria continue to pass through Macedonia on their way to the European Union. (Photo by Georgi Licovski/EPA)

A Polish Army tank takes part in the NATO Noble Jump exercise on a training range near Swietoszow Zagan, Poland, Thursday, June 18, 2015. (AP Photo/Alik Keplicz)

A woman takes a selfie next to a model of Thor during the Middle East Film & Comic Con (MEFCC) in Dubai, United Arab Emirates, Saturday, April 11, 2015. (Photo by Kamran Jebreili/AP Photo)

Model enthusiast Peter Smith poses with his collection of handmade scale model coaches at the “London Model Engineering Exhibition” at Alexander Palace on January 20, 2012 in London, England. (Photo by Dan Kitwood/Getty Images)

A reveller reacts amid a “flour war” during the “Ash Monday” celebrations, a traditional festivity marking the end of the carnival season and the start of the 40-day Lent period until the Orthodox Easter, in the port town of Galaxidi, Greece, on March 11, 2019. (Photo by Aris Messinis/AFP Photo)

The rusty emblem of the Soviet Union is seen over the ghost town of Pripyat close to the Chernobyl nuclear plant, Ukraine, Thursday, April 15, 2021. The vast and empty Chernobyl Exclusion Zone around the site of the world’s worst nuclear accident is a baleful monument to human mistakes. Yet 35 years after a power plant reactor exploded, Ukrainians also look to it for inspiration, solace and income. (Photo by Efrem Lukatsky/AP Photo)