A woman loyal to the Houthi movement holds a rifle as she takes part in a parade to show support to the movement in Sanaa, Yemen September 6, 2016. The Saudi-led Arab coalition launched a military campaign against the Huthis and their allies in March 2015, after the rebels closed in on Gulf-backed President Abedrabbo Mansour Hadi in his southern refuge of Aden, forcing him into exile. (Photo by Khaled Abdullah/Reuters)

Photographer Carlos Barria holds a print of a photograph he took in 2005, as he matches it up at the same location 10 years on, in Lafitte, south of New Orleans, United States, August 16, 2015. The print shows Tyler Teal cleaning up his home, September 14, 2005, after Hurricane Katrina struck. In 2005, Hurricane Katrina triggered floods that inundated New Orleans and killed more than 1,500 people as storm waters overwhelmed levees and broke through floodwalls. (Photo by Carlos Barria/Reuters)

“Strike Through The Mothership”. Every May for the last 3 years I have driven down to Tornado Alley to capture some amazing storms. This supercell held so much promise to drop a tornado but one small shift in the atmosphere and all that it produced was an extreme lightning show. Photo location: Broken Bow, Nebraska. (Photo and caption by Vanessa Neufeld/National Geographic Photo Contest)

Star trails are pictured from a road in Singapore. These astonishing images of night sky are captured by Singapore based photographer Justin Ng. The pictures were taken between November 2013 to January 2014. It show's star trail caused by the earth's rotation and also can be achieved by zooming the DSLR lens inward or outward in small steps using a dedicated motorized zooming device. (Photo by Justin Ng/Barcroft Media)

As national soccer teams and the photographers who have been covering them start to trickle home from the Brazil World Cup, it’s time to revisit the “On the Sidelines” project. This Reuters Pictures project was billed as a chance for photographers to share “their own quirky and creative view of the World Cup”. Photo: People watch from outside as a dancer performs inside a bar in Porto Alegre June 21, 2014. In a project called “On The Sidelines” Reuters photographers share pictures showing their own quirky and creative view of the 2014 World Cup in Brazil. (Photo by Marko Djurica/Reuters)

Fred Fugen seen training for a jump over Austria on May 12, 2014. Fearless skydivers jump from an altitude of 10,000 meters above the largest mountain in Europe. Frederic Fugen, 34, and Vincent Reffet, 29, leapt from a plane in the freezing skies above Mont-Blanc in the French Alps. The jump is from such a height the pictures show the curvature of the earth. (Photo by Dominique Daher/Barcroft Media)

These images, scanned from old glass negatives which had surfaced in northern France, were believed to have been taken by a local amateur photographer in 1916. They showed British and a few Australian soldiers, in formal or informal poses, during or just before the most murderous battle in the history of the British Empire – Battle of the Somme. Who are these British and British Empire soldiers? The identity of the soldiers is, and may always remain, a mystery... (Property of Bernard Gardin/Dominique Zanardi/Joel Scribe/The Independent Magazine)

A photo taken on August 29, 2014, shows Mount Tavurvur erupting in eastern Papua New Guinea, spewing rocks and ash into the air, forcing the evacuation of local communities and international flights to be re-routed. Mount Tavurvur, which destroyed the town of Rabaul when it erupted simultaneously with nearby Mount Vulcan in 1994, rumbled to life early in the morning on the tip of the remote island of New Britain. (Photo by Oliver Bluett/AFP Photo)