A policeman kick in the door of a residence next to the Black Panther headquarters in New Orleans as they moved in following a shootout, September 15, 1970. Other heavily armed policemen stand at ready. (Photo by Jack Thornell/AP Photo)

The model Dovima in a suit and cloche hat at Les Deux Magots cafe in Paris, France in 1955. (Photo by Richard Avedon/The Richard Avedon Foundation/The Guardian)

Two zebras stand so close in Ngorongoro Crater, Tanzania. (Photo by Zhayynn James/Solent News)

British actress Elizabeth Hurley poses for photographers during a beachside event to promote her swimwear range in Cannes, France on May 23, 2006. (Photo by Michel Dufour/WireImage)

A visitor walks on a giant chalk artwork called “Wasting Time” at the Chalk Urban Arts Festival in Sydney on October 25, 2014. The picture is the biggest 3-D artwork created in Australia by two artists, Leon Keer from Holland and Jenny McCracken from Australia. (Photo by Peter Parks/AFP Photo)

Juno, a Beluga whale, greets a young viewer at the Mystic aquarium in Connecticut, USA on December 5, 2015. (Photo by Tim Clayton/Corbis)

Lightning strikes the Willis Tower (formerly Sears Tower) in downtown on June 12, 2013 in Chicago, Illinois. (Photo by Scott Olson/Getty Images)

An alpaca is seen near the Inca citadel of Machu Picchu in Cusco December 2, 2014. Machu Picchu, a UNESCO World Heritage Site, is Peru's top tourist attraction, with the government limiting tourists to 2,500 per day due to safety reasons and concerns over the preservation of the ruins. (Photo by Enrique Castro-Mendivil/Reuters)