Iraqis who have fled fighting between security forces and al-Qaida inspired militants in their hometown of Tal Afar arrive in a car at Germawa camp for displaced Iraqis, in a hot dusty plain in the largely-autonomous Kurdish area of Dahuk, 260 miles (430 kilometers) northwest of Baghdad Tuesday, June 17, 2014. (Photo by AP Photo)

An Israeli army officer gives explanations to journalists during an army organised tour in a tunnel said to be used by Palestinian militants for cross-border attacks, July 25, 2014. (Photo by Jack Guez/Reuters)

Tommy Lindsey holds an enormous maple leaf that he found in Mount Vernon, Wash., October 28, 2013. Lindsey was walking with his family when he picked up the leaf that is more than two feet from stem to tip and more than 21 inches wide. (Photo by Frank Varga/The Skagit Valley Herald)

Performers line up during the closing ceremony of the 2014 Winter Olympics, Sunday, February 23, 2014, in Sochi, Russia. (Photo by Darron Cummings/AP Photo)

Amundsen-Scott South Pole Station experiences months of darkness. The sun dips below the horizon on March 21, after which follows several weeks of twilight before complete darkness results. Photo taken on June 25, 2009. (National Science Foundation/Jeremy Johnson)

A pistol is lies near the body of a drug suspect who was killed with two others in an alleged “buy-bust” operation before dawn on Friday, September 30, 2016, in Caloocan city, north of Manila, Philippines, in the continuing “War on Drugs” campaign of President Rodrigo Duterte. Duterte said he would be “happy to slaughter” 3 million addicts. (Photo by Bullit Marquez/AP Photo)

Russia's Ekaterina Birlova casts a shadow on the sand as she serves to Poland during a women's beach volleyball match at the 2016 Summer Olympics in Rio de Janeiro, Brazil, Tuesday, August 9, 2016. (Photo by Marcio Jose Sanchez/AP Photo)

A Russian Soyuz MS space capsule stands on the ground shortly after its landing with International Space Station (ISS) crew members Kate Rubins of the U.S., Anatoly Ivanishin of Russia and Takuya Onishi of Japan, as a rescue helicopter lands nearby, outside the town of Dzhezkazgan (Zhezkazgan), Kazakhstan, October 30, 2016. (Photo by Dmitri Lovetsky/Reuters)