A handout photograph provided by Brian Kubicki of Costa Rican Amphibian Research Center on 26 April 2016 shows a “Crystal frog”, Hyalinobatrachium dianae (H. diane). This frog was discovered by US biologist Brian Kubicki and Costa Ricans Stanley Salazar and Robert Puschendorf in a rainy forest of Costa Rican caribbean after 40 years without notice of any new example of this kind. (Photo by Brian Kubicki/EPA/Costa Rican Amphibian Research Center)

“Environmental Migrants: The Last Illusion” by photographer Alessandro Grassani, documents the life of people in Kenya, Mongolia and Bangladesh who migrate to escape environmental stresses to the city of their own countries in hopes for a better life. Here: Asia, Mongolia, March 27, 2011. A view of Ulaan Baator over the shoulder of a slumbering drunk. Alcoholism is a huge problem in the city, home to almost half of Mongolia's people. The capital's population has doubled in the past two years. High levels of unemployment and poverty await herders who abandon rural areas and arrive in the city, illiterate and untrained in any skills necessary for urban jobs. (Photo by Alessandro Grassani)

NASA handout photographs from the various Apollo missions are shown in this combination photograph. The photographs are some of more than 12,000 from NASA's archives recently aggregated on the Project Apollo Archive Flickr account. (Top L) David R. Scott, command module pilot, stands in the open hatch of the Command Module during the Apollo 9 mission March 6, 1969. (Top centre) Edwin "Buzz" Aldrin Jr.walks on the surface of the moon during the Apollo 11 mission July 20, 1969. (Top R) Neil Armstrong, Apollo 11 commander, is pictured inside the Lunar Module during the Apollo 11 mission July 20, 1969. (Bottom L) Alan Bean holds a container filled with lunar soil collected during the Apollo 12 mission November 19, 1969. (Bottom centre) Scientist-astronaut Harrison Schmitt rides in the Lunar Roving Vehicle during the Apollo 17 mission December 13, 1972. (Bottom R) Harrison Schmitt stands next to a huge, split boulder during the Apollo 17 mission December 13, 1972. (Photo by Reuters/NASA)

Body builders preparing at the backstage during the Bodybuilding Cup in Kiev, Ukraine on November 7, 2015 which includes classic bodybuilding, physicist and body fitness and bikini in the competition. (Photo by Nazar Furyk/Pacific Press)

in Qayyarah, about 31 miles (50 km) south of Mosul, Iraq, Sunday, October 23, 2016.in Qayyarah, some 50 kilometers south of Mosul, Iraq, Sunday, Oct. 23, 2016. Islamic State fighters torched a sulfur plant south of Mosul, sending a cloud of toxic fumes into the air that mingled with oil wells the militants had lit on fire to create a smoke screen. (Photo by Marko Drobnjakovic/AP Photo)

Traders try to control a camel at Pushkar Fair where animals, mainly camels, are brought to be sold and traded in the desert Indian state of Rajasthan November 6, 2016. (Photo by Himanshu Sharma/Reuters)

The damaged battleship USS California, listing to port after being hit by Japanese aerial torpedoes and bombs, is seen off Ford Island during the attack on Pearl Harbor, Hawaii, U.S. December 7, 1941. The 75th anniversary of the attack, which brought the United States into World War Two, is marked on December 7, 2016. (Photo by Reuters/U.S. Navy/National Archives)

An anti-Gaddafi fighter tests an anti-aircraft gun southwest of Sirte, Libya one of Muammar Gaddafi's last remaining strongholds, September 16, 2011. A timeline of images dating from 2010 from Sirte, Libya, the home town of deposed Libyan leader Muammar Gaddafi. Libyan forces battling Islamic State in the city of Sirte say they have defeated the militant group after months of street to street fighting backed by U.S. air strikes. Islamic State took control of the city more than a year ago and set up its main base outside Syria and Iraq. (Photo by Goran Tomasevic/Reuters)