A parishioner of the St. Joseph the Worker Parish in Nairobi's Kangemi slum carries the vestments to be worn by Pope Francis during his visit to Kenya on November 24, 2015 in Kenya. Pope Francis makes his first visit to Kenya on a five day African tour that is scheduled to include Uganda and the Central African Republic. Africa is recognised as being crucial to the future of the Catholic Church with the continent's Catholic numbers growing faster than anywhere else in the world. (Photo by Nichole Sobecki/Getty Images)

An Zi, is squashed amongst other commuters in a subway train on his way to work in Beijing, China, November 12, 2015. An, a movie producer, moved to Dongsanqi village in Changping this year. His commute to work can take about 2 hours, with transportation costs topping 200 yuan a month, or about a fifth of his monthly rent. (Photo by Jason Lee/Reuters)

A poster by street artist Aaron Li-Hill as part of the "Brandalism" project is displayed at a bus stop in Paris, France, November 28, 2015, ahead of the United Nations COP21 Climate Change conference in Paris. Brandalism is a revolt against corporate control of the visual realm. Following on in the guerilla art traditions of the 20th Century and taking inspiration from Agitprop, Situationist and Street Art movements, the Brandalism project sees artists from around the world collaborate to challenge the authority and legitimacy of commercial images within public space and within our culture. (Photo by Benoit Tessier/Reuters)

Marion (L) and Nikola (R), members of the Sport Saber League, pose with their light sabers in front of the Eiffel tower in Paris, France, November 26, 2015. Three "Star Wars" fans opened the French Academy of the Sport Saber League in September 2015 due to the increase interest for light saber fighting and the upcoming movie "The Force Awakens" which will premier in Paris, December 16th, two days before its worldwide official release. (Photo by Charles Platiau/Reuters)

A small section of the expanding remains of the Veil Nebula, a massive star that exploded about 8,000 years ago. The entire nebula is 110 light-years across, covering six full moons on the sky as seen from Earth, and resides about 2,100 light-years away in the constellation Cygnus, the Swan. Image taken by NASA's Hubble Space Telescope. Released September 24, 2015. (Photo by Reuters/NASA/ESA/Hubble Heritage Team)

Some of the most powerful narratives of the past decade have been produced by a forward-thinking generation of women photojournalists as different as the places and the subjects they have covered. National Geographic's “Women of Vision” exhibit features the work of 11 photographers and is on display at the Fernbank Museum of Natural History in Atlanta until January 3, 2016. Here: Nujood Ali stunned the world in 2008 by obtaining a divorce at age 10 in Yemen, striking a blow against forced marriage. (Photo by Stephanie Sinclair/National Geographic)

Nikolai Vasilyev, 62, dressed as Father Frost, Russian equivalent of Santa Claus, water-skis along the Yenisei River outside Siberian city of Krasnoyarsk, Russia, December 10, 2015. Vasilyev, a teacher of the Krasnoyarsk Aerospace Academy, constructed the self-made water skis to travel on the water surface. The skis are made of plastic foam and the sticks are designed to propel him forward. (Photo by Ilya Naymushin/Reuters)

A couple hugs while standing near a Christmas tree made out of plastic bins and plastic hampers outside the Museum of History in Monterrey, Mexico, December 4, 2015. The humble Christmas tree has a rich history, from evergreen trees used to symbolise eternal life in Ancient Egypt to tree worship among pagan Europeans. The modern version has its origins in Germany, where the song “O Tannenbaum” is still a festive favourite. Today the traditional tree with lights and decorations appears in cities including Washington, Moscow and Beirut. Alternative constructions range from recycled rubbish in Mexico City to old window frames in Rakvere, Estonia. Whatever the shape or size, the message is the same: Merry Christmas. (Photo by Neil Hall/Reuters)