People are reflected in a shop window as they walk along a street in a shopping district in Tokyo, Japan June 25, 2015. (Photo by Thomas Peter/Reuters)

A U.S. Army B-24 Liberator Bomber is hailed by a ground crewman as it takes off over a line of shark- nosed fighter planes at an advanced base in China on a mission on October 10, 1943, to bomb Japanese installations. (Photo by AP Photo)

M42 Subtle V1 cropped. One of the most well-known astronomical objects in our universe is the Orion Nebula and this image depicts the wider region of the Orion Molecular Cloud Complex that is its home. This complex also includes another popular target for astrophotographers, the Horsehead Nebula, as well as Barnard’s Loop and the Running Man Nebula, which can be seen to the left of this photograph. (Photo by Patrick Gilliland)

The Enemy, 1944. With the outbreak of world war two, photojournalism was enlisted in defence of Mother Russia. In this photo by Anatoli Egorov, who was wounded in action, corporal Stepan Vasiljevich Ovcharenko shoots at enemy troops with a machine gun. (Photo by Anatoli Egorov/Lumiere Brothers Center for Photography)

A women wearing a mask to protect from extreme smog visits the Tiananmen Gate in Beijing December 8, 2015 as China's capital issues its first ever "red alert" for pollution. (Photo by Damir Sagolj/Reuters)

Venezuela: An anti-government protester wearing a Guy Fawkes mask throws a molotov cocktail at the Bolivarian National Police during clashes in Caracas, Venezuela, Thursday, April 17, 2014. Opposition protesters have been demonstrating against high crime, high inflation and shortages of basic goods since mid-February. (Photo by Ramon Espinosa/AP Photo)

A sign advising to pray for rain hangs above an exhibit area at the 47th Annual World Ag Expo in Tulare, February 12, 2014. About a hundred years ago, when urban water systems were being developed throughout the state, the city of Sacramento wrote protections from metering into its charter, vowing that residents would always have the right to use as much water as they needed. But on Tuesday, the state's top water regulators released a framework for enforcing California's first statewide mandatory restrictions on urban water use – cuts of 25 percent for non-agricultural users ordered last week by Democratic Governor Jerry Brown as a devastating drought enters its fourth year. (Photo by David McNew/Reuters)

A Grevy’s zebra gets itself noticed at ZSL Whipsnade Zoo in Whipsnade, England on April 20, 2018. (Photo by Tony Margiocchi/Barcroft Media)