Singer Rihanna prepares for a photoshoot with photographer Annie Leibovitz in Havana, Cuba, May 28, 2015. (Photo by Reuters/Stringer)

The Jet Propulsion Lab team's RoboSimian robot turns on a valve at a simulated disaster-response course during day one of the Defense Advanced Research Projects Agency (DARPA) Robotics Challenge finals in Pomona, California, June 5, 2015. (Photo by David McNew/Reuters)

Rolando Pujol Rodriguez photographed the Cuban raft exodus in 1994, and twenty years later Enrique de la Osa took portraits of some of the people who made it to the United States, in this story which combines archive and present day images. Here: People put the finishing touches to a makeshift boat on a rooftop before lowering it onto a truck and launching it into the Straits of Florida towards the U.S., on the last day of the 1994 Cuban raft exodus in Havana, in this September 13, 1994 file photo. (Photo by Rolando Pujol Rodriguez/Reuters)

Swimmers in fancy dress splash as they participate in the New Year's Day Loony Dook swim at South Queensferry, Scotland January 1, 2015. (Photo by Russell Cheyne/Reuters)

In this July 30, 2014 photo, neighbors help gravely injured Mohammed al-Selek, 39, wounded by an Israeli mortar strike as he lays next to the body of Palestinian journalist Rami Reyan who was killed, in the Shijaiyah neighborhood of the northern Gaza Strip. Al-Selek's life changed forever last July 30, when the shells slammed into his home killing all his three children, his father and six other relatives. A year later, al-Selek, who lost his leg during the airstrike, still struggles to recover and come to terms with his family's loss in the 50-day Israel-Hamas war. (Photo by Adel Hana/AP Photo)

The Temple of Heaven (The Qi Nian Temple) is illuminated as Beijing celebrates the New Year's Eve at the Temple of Heaven Park on December 31, 2011 in Beijing, China. (Photo by Lintao Zhang/Getty Images)

An internally displaced woman collects water from a pond to construct a mud-house at the Aboushok camp in El Fasher, North Darfur, Sudan, November 17, 2015. The conflict in Sudan's Darfur region that erupted 12 years ago shows no sign of ending. But it hasn't stopped displaced youngsters, some of whom have spent their entire lives in refugee camps, from dreaming big. Twelve children aged 12 explain their hopes and dreams for the future; ambitions include becoming a doctor, an engineer and a teacher. (Photo by Mohamed Nureldin Abdallah/Reuters)

A Tibetan man stirs butter tea made for the arriving guest during the function organised to mark Losar or the Tibetan New Year at a Tibetan Refugee Camp in Lalitpur February 19, 2015. Tibetans across the world marked the arrival of the New Year with prayers and festivities. (Photo by Niranjan Shrestha/AP Photo)