Students from Langata primary school run past riot police as they protest against a perimeter wall illegally erected by a private developer around their school playground in Kenya's capital Nairobi January 19, 2015. Riot police used teargas to disperse students at a school in Nairobi as the children protested against the potential loss of their playground. The playground was fenced off in December, during the school holidays, by a prominent developer who also claims ownership of the land. The title to the contested site is said to be in the name of Airport View Housing Limited, according to local media, with plans to use the space to build a parking lot for a hotel. (Photo by Thomas Mukoya/Reuters)

Reuters photographer Bobby Yip took a series of portraits of people taking part in the “Occupy Central” protests in Hong Kong, and asked them why they had joined the demonstrations. China rules Hong Kong under a “one country, two systems” formula that accords the territory limited democracy. Tens of thousands of mostly student protesters are demanding Beijing give them full democracy, with the freedom to nominate election candidates. The unrest is the worst in Hong Kong since China resumed its rule over the former British colony in 1997. (Photo by Carlos Barria/Reuters)

NASA says it could be another 20 years before humans touch down on Mars, but in a sense, the Mars Society has been exploring the red planet for more than a decade – in Utah. Photo: Csilla Orgel, a geologist of Crew 125 EuroMoonMars B mission, makes her way back to the Mars Desert Research Station (MDRS) in the Utah desert March 3, 2013. The MDRS aims to investigate the feasibility of a human exploration of Mars and uses the Utah desert's Mars-like terrain to simulate working conditions on the red planet. Scientists, students and enthusiasts work together developing field tactics and studying the terrain. All outdoor exploration is done wearing simulated spacesuits and carrying air supply packs and crews live together in a small communication base with limited amounts of electricity, food, oxygen and water. Everything needed to survive must be produced, fixed and replaced on site. (Photo by Jim Urquhart/Reuters)

Gers, traditional Mongolian tents, are seen on a hill in an area known as a ger district in Ulan Bator June 26, 2013. Approximately 60 percent of the population of Ulan Bator live in settlements known as ger districts and in many cases residents have limited access to basic services such as water and sanitation. According to a 2010 National Population Center census, every year between thirty and forty thousand people migrate from the countryside to the capital Ulan Bator. Ger districts in the city have been expanding rapidly in recent years. Mongolia is the world's least densely populated country, with 2.8 million people spread across an area around three times the size of France. (Photo by Carlos Barria/Reuters)

In this handout image provided by Ogilvy, a burger made from cultured beef, which has been developed by Professor Mark Post of Maastricht University in the Netherlands (pictured) is shown to the media during a press conference on August 5, 2013 in London, England. The in-vitro burger, cultured from cattle stem cells, the first example of what its creator says could provide an answer to global food shortages and help combat climate change, was fried in a pan and tasted by two volunteers. The burger is the result of years of research by Dutch scientist Mark Post, a vascular biologist at the University of Maastricht, who is working to show how meat grown in petri dishes might one day be a true alternative to meat from livestock.The meat in the burger has been made by knitting together around 20,000 strands of protein that has been cultured from cattle stem cells in Post's lab. (Photo by David Parry)

A polar bear whose bottom half is caked in oily black gunk. A whale wrapped in striped fabric: a pseudo straightjacket. These are the messes climate change leaves behind, the things we know are happening but often don’t have the opportunity to see with our own eyes. Swiss street art duo Christian Rebecchi and Pablo Togni, otherwise known as NeverCrew, met in art school when they were 15 and started making work together soon after. As a team, the artists adorn the world with eye-popping and gut-wrenching images depicting the consequences of humanity’s actions on earth. (Photo by NeverCrew/The Huffington Post)

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 new curvy Barbie doll body shape (L) is seen next to the traditional Barbie in a combination of photos released by Mattel on January 28, 2016. Barbie, the world's most famous doll, has a new body. In fact, she has three new bodies – petite, tall and curvy. Some 57 years after the impossibly busty and narrow-waisted blue-eyed Barbie doll was first introduced, California-based toy maker Mattel on Thursday released the new models, which it says better reflect a changing world. (Photo by Reuters/Mattel)