Militant Islamist fighters take part in a military parade along the streets of Syria's northern Raqqa province June 30, 2014. The fighters held the parade to celebrate their declaration of an Islamic “caliphate” after the group captured territory in neighbouring Iraq, a monitoring service said. The Islamic State, an al Qaeda offshoot previously known as Islamic State in Iraq and the Levant (ISIL), posted pictures online on Sunday of people waving black flags from cars and holding guns in the air, the SITE monitoring service said. (Photo by Reuters/Stringer)

Artist C. K. Wilde creates intricate collage compositions using pieces of paper currency from all over the world. His collages have referenced subjects ranging from space exploration, to mythology, religion, slavery, ecology, the history of warfare, the history of money, and art history. Photo: “Great Crash”. (Photo by C. K. Wilde)

Axel, a research prototype rover for exploring the Moon, Mars and other planets, is remotely driven over rocks as engineers from Jet Propulsion (JPL) and grad students from Caltech (California Institute of Technology) demonstrate its mobile over the steep and rocky grounds of the JPL Mars Yard on January 14, 2009 in Pasadena, California. The rover is capable of descending cliffs or into craters and returning by a cable tethered to its starting point. Development of the Axel rover is a point effort funded by NASA Exploration Systems Mission Directorate (ESMD) and lead by Principal Investigator Issa Newnas and Co-Investigator and Caltech professor of mechanical engineering bio engineering Joel Burdick. (Photo by David McNew/Getty Images)

U.S. Army soldiers carry an injured soldier who was shot in the leg, through a poppy field on April 24, 2011 in the Arghandab River Valley, Kandahar Province, Afghanistan. The injured was evacuated to a waiting Blackhawk UH-60A helicopter by Task Force Thunder Brigade, Charlie company 1st of the 52nd Aviation regiment from Fairbanks, Alaska. It is feared that as weather improves with the approaching summer that the casualty toll will rise. (Photo by Paula Bronstein/Getty Images)

Sumatran tiger Jumilah is seen with one of her cubs on display at Taronga Zoo on October 25, 2011 in Sydney, Australia. The Sumatran tiger cubs, born in August to mother Jumilah, will meet the public for the first time this week. (Photo by Mark Kolbe/Getty Images)

A Sri Lankan child uses an inflatable tube to wade through floodwaters after heavy rains in Biyagama suburb of Colombo, Sri Lanka, 06 June 2021. Many parts of the island have been inundated due to heavy monsoon rains. According to the Sri Lanka Disaster Management Center, at least 14 people have been killed so far and more than 245,212 people affected across the country. (Photo by Chamila Karunarathne/EPA/EFE)

A placard featuring an image of Russian President Vladimir Putin and reading “We are with him for the sovereignty of Russia! And you?” is seen left in front of the Russian State Duma building in central Moscow on February 24, 2022. (Photo by Kirill Kudryavtsev/AFP Photo)