A man salts a downtown sidewalk in Washington, Thursday, March 5, 2015, as snow begins to fall. The U.S. federal government said its offices in the Washington area will be closed Thursday because of a new round of winter weather expected in the region. The Office of Personnel Management said non-emergency personnel in and around Washington were granted excused absences for the day. Emergency employees and telework-ready employees were expected to work. (AP Photo/Andrew Harnik)

An Aden civilian crouching in terror as British soldiers threaten him during Arabian demonstrations in Crater. (Photo by Express Newspapers/Getty Images). 1967

A man looks on from the sea as Italian model and actress Elisa Sednaoui poses for photographers a day before the 72nd Venice Film Festival in Venice, Italy, September 1, 2015. Sednaoui will be hosting the opening and closing ceremonies of the film festival. (Photo by Stefano Rellandini/Reuters)

An officer wipes sweat off the face of a Chinese People's Liberation Army (PLA) honor guard soldier as they rehearse for a welcoming ceremony for New Zealand's Governor-General Sir Jerry Mateparae at the Great Hall of the People in Beijing, Tuesday, July 21, 2015. (Photo by Mark Schiefelbein/AP Photo)

A wax figure of U.S. actress Scarlett Johansson stands outside Madame Tussauds New York attraction shortly after the figure was unveiled in Times Square in New York, July 30, 2015. (Photo by Mike Segar/Reuters)

Miss Venezuela Edymar Martinez poses during the swimsuit contest during the Miss International beauty pageant in Tokyo on November 5, 2015. Martinez won the Miss International title. Representatives of 70 countries and regions from all over the world took part in the annual beauty contest. (Photo by Toru Yamanaka/AFP Photo)

Tourists look at other festival-goers playing in the mud during the Boryeong Mud Festival at Daecheon beach in Boryeong, about 190 km (118 miles) southwest of Seoul, July 19, 2013. About 2 to 3 million domestic and international tourists visit the beach during the annual mud festival, according to the festival organisers. (Photo by Lee Jae-Won/Reuters)

The antennas of the European Southern Observatory's Atacama Large Millimeter/Submillimeter Array, also known as ALMA, are set against the splendor of the Milky Way in this picture by Babak Tafreshi. Construction of the full ALMA array is due to be completed in Chile's Atacama Desert in 2013, but the facility is already making scientific observations with a partial array of antennas. (Photo by ESO/B. Tafreshi/TWAN)