A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

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)

Model Heidi Klum attends her 8th Annual Halloween Party at The Green Door on October 31, 2007 in Los Angeles, California. (Photo by Charley Gallay/Getty Images)

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

Civilians present their rations cards in order to receive humanitarian food aid being distributed by the Iraqi Red Crescent, in the eastern side of Mosul, Iraq, Tuesday, January 31, 2017. Iraqi forces declared Mosul's eastern half fully liberated, just over three months after the operation to retake the city from IS was formally launched in October. (Photo by Khalid Mohammed/AP Photo)

Expedition 44 flight engineer and NASA astronaut Scott Kelly seen inside the Cupola, a special module which provides a 360-degree viewing of the Earth and the International Space Station. Kelly is one of two crew members spending an entire year in space. (Photo by Scott Kelly/NASA)

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