A propaganda troupe perform a flag- waving routine outside the central railway station in Pyongyang, North Korea on September 27, 2017. (Photo by Ed Jones/AFP Photo)

Indian Air Force personnel parade during the 85th Air Force Day celebrations at Hindon Air Force base in Ghaziabad on October 8, 2017. (Photo by AFP Photo/Stringer)

Trees are reflected on the surface of a lake in the Okefenokee swamp lands in Georgia, USA on October 21, 2017. (Photo by Chris Moore/Solent News & Photo Agency)

Spectators pass through security screening ahead of the New Year's Eve celebration in Times Square in New York, on Sunday, December 31, 2017. (Photo by Peter Morgan/AP Photo)

Aerial photo taken on March 4, 2017 shows cole flower fields in Luoping County, southwest China's Yunnan Province. (Photo by Xinhua/Barcroft Images)

A man shaves blocks of salt from the Danakil Depression on 28 March 2017, in Afar, Ethiopia. Every morning, hundreds of men converge on a dry lakebed in a remote corner of Ethiopia, where they cleave the ground open with handaxes to extract salt, just as their fathers and grandfathers once did. (Photo by Zacharias Abubeker/AFP Photo)

A hippopotamus is sprayed with water on a hot summer day at Anna National Zoological Park in Chennai, India on April 26, 2017. (Photo by Arun Sankar/AFP Photo)

A reindeer is seen as people visit ice sculptures illuminated by coloured lights at the Harbin Ice and Snow Festival to celebrate the new year in Harbin on January 4, 2017. (Photo by Nicolas Asfouri/AFP Photo)