A street artist dances tango in Buenos Aires, Argentina, Tuesday, January 20, 2015. Tango is a partner dance that originated in the 1890's along the Rio de la Plata, the border between Uruguay and Argentina. UNESCO approved in 2009, a joint proposal by the two nations to include the dance in its Intangible Cultural Heritage List. (Photo by Rodrigo Abd/AP Photo)

A young boy scoops water from a hand-dug well in the dry riverbed near Matinyani, in the semi-arid Kitui County in southeastern Kenya, 22 March 2015, the World Water Day. Residents of Kitui County and other arid and semi-arid areas of the country have been hard-hit by extremely poor rainfall this year while the government said in previous month that some 1.6 million people countrywide are facing acute starvation due to the drought and will need relief food over the next six months. Residents of Matinyani say they haven't seen a drop of rain in nearly four months. Thousands of Kenyans in rural areas walk tens of kilometers just to fetch water to drink and to be used in their homes. According to an estimate by UNESCO (United Nations Educational, Scientific and Cultural Organization), 17 million people lack access to safe water in Kenya, where the drought is a perennial problem. (Photo by Dai Kurokawa/EPA)

The villas of Marabe Al Dhafra in Abu Dhabi, United Arab Emirates are home to approximately 2,000 people. Located in one of the hottest regions of the world, the record high temperature here is 49.2C° (120.6F°). (Photo by Benjamin Grant/Penguin Random House)

A Nepalese man sits outside a Hindu temple as a goat rests on a parked scooter in Khokana, Lalitpur District, Nepal, Monday, September 26, 2016. Writing on the wall offers prayers to Hindu god Shiva. (Photo by Niranjan Shrestha/AP Photo)

A woman prays at the edge of a river during a protest against the building of a pipeline near the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S. November 2, 2016. (Photo by Stephanie Keith/Reuters)

“Leopard Hunting a Stork”. “One-shot capture. I watched the leopard stalking the stork, I only had time to focus at 400mm, no time to change to high speed, I watched the stork, and as soon as it flapped its wings, I shot one shot”. (Photo by Paul Rifkin/National Geographic Travel Photographer of the Year Contest)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

A love story with two log choppers. “In 1993, I was working on a project about life in the Olomouc region of Czechoslovakia. One day, I came to the village of Dlouhá Loučka-Křivá and went into a courtyard where I saw two old people, a husband and wife, sawing firewood for winter. They were working quietly, concentrating. I watched them fetch a beam from a wrecked barn, but they didn’t discuss how they planned to carry it to the saw. The woman faced one way, the man the other. When they realised, the woman eventually turned and followed her husband. The picture I took is the picture of many relationships – when each partner wants something different, but they have to come to an agreement, pull together eventually”. (Photo by Jindrich Streit)