A “Free Syrian Army” fighter in the Bustan Pasha neighborhood of Aleppo, Syria, August 21, 2013. (Photo by James Lawler Duggan)

A man takes a photo of a radio antenna that's part of the Atacama Large Milimeter Array Observatory on March 12, 2013 at Llano de Chajnantor, about 43 miles (70 kilometers) from San Pedro de Atacama, Chile. The $1.5 billion ALMA facility, which had its official inauguration on March 13, is considered the world's most expensive ground-based observatory. (Photo by Felipe Trueba/EPA)

Student protestors, including one girl with a camera, struggle with soldiers from the Chinese Army, the PLA. Tiananmen Square, 1989. (Photo by Jeff Widener/Associated Press)

Mercury and Maia, fueled and overhauled, are waiting in the Tay at Dundee, for favorable weather to start the flight to the Cape, a distance of 6,370 miles. The composite machine moored in the Tay River, at Dundee, on September 23, 1938. (Photo by AP Photo)

A man looks at kebabs cooking on the street side in Rawalpindi, Pakistan October 2, 2017. (Photo by Caren Firouz/Reuters)

Catherine Hollis of Chester, Pa., and Izzy Weintraub of Atlantic City eat Cherrystone clams at Atlantic City's annual clam-eating contest September 16, 1946. They finished 96 and 66 clams respectively in 20 minutes. (Photo by Sam Myers/AP Photo)

Tandem hair drying is possible with a new two-hood attachment for any electric hair dryer manufactured by Postcraft Co of Tucson, Ariz., shown in Chicago, January 27, 1965. A Y adapter permits two hoses to be attached to the dryer. (Photo by Edward Kitch/AP Photo)

A man drinks at a "colored" water cooler in a streetcar terminal in Oklahoma City, July 1939. (Photo by Reuters/Library of Congress)