A member of the Revolutionary Armed Forces of Colombia (FARC) pose for a picture at a camp in the Colombian mountains on February 2005. (Photo by Frank Piasecki Poulsen)

People skate through the forest at Domaine de la Foret Perdu or the Lost Forest, a 15km weaving and zambonied forest trail made for skating in Notre-Dame-du-Mont-Carmel, near Three Rivers, Quebec January 29, 2017. (Photo by Christinne Muschi/Reuters)

Two holidaymakers amuse themselves with a porter's trolley whilst waiting for their train at Euston Station, London, 5th August 1939. (Photo by A. J. O'Brien/Fox Photos/Getty Images)

“Mr Big Dipper”, Nicholas Roemmelt (Denmark). A stargazer observes the constellation of the Big Dipper perfectly aligned with the window of the entrance to a large glacier cave in Engadin, Switzerland. This is a panorama of two pictures, and each is a stack of another two pictures: one for the stars and another one for the foreground, but with no composing or time blending. (Photo by Nicholas Roemmelt/National Maritime Museum/The Guardian)

A conductor (C) collects fares from candy floss sellers as they travel in a tram to a marketplace early morning in Kolkata, India, December 23, 2015. (Photo by Rupak De Chowdhuri/Reuters)

A boy looks for scrap metal using an improvised magnetic tool near a construction site in New Delhi, India, March 21, 2016. (Photo by Cathal McNaughton/Reuters)

Nuns from the United States dance as they wait for the Holy Mass with Pope Francis (not seen) at the Campus Misericordiae in Brzegi, Poland, 31 July 2016. Today Pope Francis will celebrate the holy mass ending the World Youth Day 2016 in Poland. (Photo by Marcin Obara/EPA)

Early morning storms over the Masai Mara National Reserve, Kenya on August 26, 2016. (Photo by Action Press/Rex Features/Shutterstock)