1st prize in the People Observed Portraits Stories category. Carla Kogelman, the Netherlands. The photo shows Hannah and Alena, two sisters living in the rural village of Merkenbrechts, Austria. (Photo by Carla Kogelman/World Press Photo)

Actor George Clooney from the film “Ides Of March” arrives at the Hotel Excelsior during the 68th Venice Film Festival on August 31, 2011 in Venice, Italy. (Photo by Gareth Cattermole/Getty Images)

An elephant “kisses” a visitor during a show at an elephant training school in Xishuangbanna, Yunnan province, April 18, 2015. Some 16 elephants live at the school and give four 30-minute performances everyday for visitors. (Photo by Wong Campion/Reuters)

Cheering The News of Germany's Surrender New Yorkers Gather around a youth wearing a mask of Adolf Hitler to cheer the news of the Surrender of Germany on May 7. The Crowd is gathered in times Square, New York. May 08, 1945. (Photo by New York Post/Photo Archives, LLC via Getty Images)

Robot couple Xiaolan (L) and Xiaotao carry trays of food at a restaurant in Jinhua, Zhejiang province, China, May 18, 2015. The restaurant, which opened on Monday, has two robots delivering food for customers. The robots were designed as a couple, Xiaolan and Xiaotao, according to local media. (Photo by Reuters/Stringer)

“Kids of Sapa”. Four little beautiful Hmong girls from Lao Chai Village, near Sapa, Vietnam. (Photo and caption by Felipe Hanower/National Geographic Traveler Photo Contest)

These stunning pictures show a normally vicious tiger calmly swimming in a pool of algae, on Jule 9, 2014. The powerful cat takes a refreshing break by taking a dip in the bright green algae. But it looks like this big cat is scared of getting his head wet as he strains to keep it above the water. After splashing around for a bit the tiger gets out and tries to air-dry with specks of the vegetation dripping off his fur. The striking pictures were taken at Copenhagen zoo by snapper Soren Lundgren Neilson. (Photo by Soren Nielsen/Caters News)

On August 31, 2012, a long filament of solar material that had been hovering in the sun's atmosphere, the corona, erupted out into space at 4:36 p.m. EDT. The coronal mass ejection, or CME, traveled at over 900 miles per second. The CME did not travel directly toward Earth, but did connect with Earth's magnetic environment, or magnetosphere, causing aurora to appear on the night of Monday, September 3. (Photo by NASA/GSFC/SDO via The Atlantic)