Construction workers take a lunch break on a steel beam atop the RCA Building at Rockefeller Center, New York, September 29, 1932. In the background is the Chrysler Building. (Photo by AP Photo)

A Palestinian protester uses a sling shot to throw stones towards Israeli security forces during clashes on the Israeli border Eastern Gaza City, Friday, November 6, 2015. (Photo by Adel Hana/AP Photo)

Giant panda Meng Meng plays on a tree at a Siberian tiger-breeding base in Changchun, China on December 10, 2015. (Photo by Xu Chang/Xinhua Press/Corbis)

A couple hugs while standing near a Christmas tree made out of plastic bins and plastic hampers outside the Museum of History in Monterrey, Mexico, December 4, 2015. The humble Christmas tree has a rich history, from evergreen trees used to symbolise eternal life in Ancient Egypt to tree worship among pagan Europeans. The modern version has its origins in Germany, where the song “O Tannenbaum” is still a festive favourite. Today the traditional tree with lights and decorations appears in cities including Washington, Moscow and Beirut. Alternative constructions range from recycled rubbish in Mexico City to old window frames in Rakvere, Estonia. Whatever the shape or size, the message is the same: Merry Christmas. (Photo by Neil Hall/Reuters)

Tourists watch the Christmas Day sunrise behind Diamond Head from Waikiki Beach in Honolulu, Friday, December 25, 2015. (Photo by J. David Ake/AP Photo)

Indian policemen carry the body of one of their colleagues killed in a rebel attack in the town of Dinanagar, in the northern state of Punjab, India, Monday, July 27, 2015. Indian forces fought an extended gunbattle Monday with militants who attacked a moving bus and stormed into a police station in a northern town bordering Pakistan. (Photo by Channi Anand/AP Photo)

A picturesque supercell formation in the northwest of Booker, Texas from June 2013. (Photo by Mike Olbinski/Barcroft Media)

Surfer Hannah Cornett attends The 2014 ESPYS at Nokia Theatre L.A. Live on July 16, 2014 in Los Angeles, California. (Photo by Jason Merritt/Getty Images)