A woman dressed in an alien space suit carries an American flag and a sign that reads “Women's Revolution 1971” as she marches in a Women's Liberation demonstration on Fifth Avenue in New York, August 26, 1971. (Photo by Marty Lederhandler/AP Photo)

Lightning streaks across the sky as lava flows from a volcano in Eyjafjallajokul April 17, 2010. (Photo by Lucas Jackson/Reuters)

Gas-masked men of the British Machine Gun Corps with a Vickers machine gun during the first battle of the Somme, 1916. (Photo by General Photographic Agency/Getty Images)

A man prays to mourn victims of the March 11, 2011, earthquake and tsunami in front of a ship brought ashore by the disaster in Kesennuma, Miyagi Prefecture, Japan. (Photo by Kyodo via Reuters)

A couple passes the sculpture “Transformer” by Chinese artist Bi Heng during snowfall in Kassel, central Germany, Tuesday March 12, 2013. Frankfurt airport closed, a quarter of flights out of Paris were canceled, Belgium suffered record traffic jams and high-speed trains were stuck in stations – all because of a sudden dump of oddly late snowfall on Western Europe. Less prepared for the kind of heavy snow that regularly hits northern and eastern neighbors, France, Britain and Belgium struggled Tuesday to keep moving amid the frosty, blustery conditions. (Photo by Uwe Zucchi/AP Photo/Dpa)

This image is NGC 6543 known as the Cat's Eye Nebula as it appears to the Chandra X-Ray Observatory and Hubble Telescope. A planetary nebula is a phase of stellar evolution that the sun should experience several billion years from now, when it expands to become a red giant and then sheds most of its outer layers, leaving behind a hot core that contracts to form a dense white dwarf star. This image was released October 10, 2012. (Photo by J. Kastner/NASA/CXC/RIT)

“Unexpected x2 (a.k.a. “how much is that doggie in the window”)”. Taiwan, 2011. (Photo and caption by Asian (Street) Impressions)

Scores of internally displaced Muslims are at the heart of the humanitarian crisis in Central African Republic, where violence between Christians and Muslims has threatened to spiral into genocide. Photo: An internally displaced woman carries her child in a camp for internally displaced people (IDPs), located at Bangui International Airport, April 10, 2014. (Photo by Goran Tomasevic/Reuters)