A protester uses molotov cocktails against riot police during May Day protests on May 1, 2010 in Athens, Greece. (Photo by Milos Bicanski /Getty Images)

Finia, a visiting student from Hanover, cools off under a water sprinkler in front of the Chancellery on June 10, 2010 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Prayer flags fly at Namgyal Tsemo Monastery above the town of Leh in Ladakh, India September 24, 2016. High in the Indian Himalayas, young novice monks in maroon robes take their lessons inside the 15th-century Thiksey monastery. (Photo by Cathal McNaughton/Reuters)

Cosplay fans attend the Animation Comic Games (ACG) Culture Festival in Xi'an, capital of northwest China's Shaanxi Province, May 28, 2017. The festival kicked off on Saturday, attracting lots of cosplay fans. (Photo by Liu Xiao/Xinhua)

Camera trapper Xavier Hubert-Brierre put this large mirror on the side of a road through the jungle in Gabon and left a camera there to record how the animals would respond to their own reflections. A silverback gorilla thought it was seeing another silverback and responded by trying to scare off the potential challenger… (Photo by Xavier Hubert-Brierre/Johns Hopkins University Press)

Villagers take part in a ritual celebrating the pagan god Yurya and pray for plentiful future harvests in the village of Pogost, Belarus May 6, 2016. (Photo by Vasily Fedosenko/Reuters)

Sete Tamang, 20, avalanche survivor, waits to receive the bodies of his colleagues outside a morgue at Teaching Hospital in Katmandu, Nepal, Monday, October 20, 2014. Nepal was wrapping up rescue operations in its northern mountains Monday, saying all the hikers believed to have been stranded on a trekking route by a series of deadly blizzards are now safe. (Photo by Niranjan Shrestha/AP Photo)

Women walk through the snow on Wimbledon common with their dogs on February 10, 2012 in London, England. The Met Office cold weather alert remains at Level 3 as southern parts of England continue to suffer from cold weather and freezing conditions, with further snowfall overnight. (Photo by Peter Macdiarmid/Getty Images)