In this Wednesday, July 13, 2016, handout image provided by Solar Impulse, the Solar Impulse 2 flying over the pyramids, Egypt Cairo. The experimental solar-powered airplane has arrived in Egypt as part of its global voyage. (Photo by Jean Revillard, Rezo via the AP Photo)

In an observance of Epiphany, Russian Orthodox believers swim in an icy pond outside Nizhny Novgorod, Russia. (Photo by Olga “Zwezdochka”)

The Euro sculpture is partially reflected in a puddle on a cobblestone pavement in front of the headquarters of the European Central Bank in Frankfurt on Jan. 21. (Kai Pfaffenbach/Reuters)

Hotel staff practice self-defence skills after a training session given by team member of Special Weapons and Tactics (SWAT) team, in Hangzhou, Zhejiang province, April 7, 2016. (Photo by Reuters/Stringer)

A man stands on a mountain summit as he looks over the Inntal valley in the western Austrian village of Gnadenwald, Austria on July 18, 2017. (Photo by Dominic Ebenbichler/Reuters)

Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

A flock of Adjutants storks sit on a garbage dump at Borgaon in Guwahati, Assam, India, 17 October 2019. Wildlife activists and environmentalists have protested in the past for shifting the garbage dump to another site since it is situated near the Deepor Beel Bird Sanctuary. (Photo by EPA/EFE/Stringer)

A female Chinese People's Liberation Army soldier looks at members of an honor guard preparing for a welcome ceremony for visiting German President Joachim Gauck, outside the Great Hall of the People in Beijing, Monday, March 21, 2016. (Photo by Andy Wong/AP Photo)