Russian pop art photographer Sergey Chilikov captures a nation liberated from the social oppression of late-era Soviet rule – at parties, in the streets, and bouncing high. His exhibition, Photoprovocations, will be at Photo London, 19-22 May. Here: Yoshkar-Ola, Matrosova Street (1995). (Photo by Sergey Chilikov)

Tattoo enthusiast Lauren Brock poses to display her body art work during the International London Tattoo Convention in east London, Britain September 26, 2015. (Photo by Neil Hall/Reuters)

A handout picture provided by Solar Impulse on 18 March 2015 shows the Swiss solar-powered plane Solar Impulse 2, HB-SIB, taking off with Swiss explorer Andre Borshberg on board for the third leg Ahmedabad to Varanasi, of the Round-The-World, in Ahmedabad, India, 18 March 2015. Swiss explorers Bertrand Piccard and Andre Borschberg attempt to circumnavigate the world flying with an aircraft, with a 72 metres wingspan, powered only by solar energy without a drop of fuel. (Photo by EPA/Solar Impulse)

As an American in 1990s Cuba, Tria Giovan risked being branded a traitor. But the photographer continued to visit and, from the dance hall to the hair salon, she captured the resilient spirit of the Cuban people. The 120 images in Tria Giovan’s “The Cuba Archive” are from the period in the 90s when, as an American, travel to Cuba could have seen her branded a traitor, as the country was subject to a US trade embargo. Her trip required lots of planning – and patience. (Photo by Tria Giovan/The Guardian)

A Ugandan soldier, part of the 9,000-strong African Union Mission in Somalia, (AMISOM) walks through the Banadir soccer stadium on August 15, 2011 in Mogadishu, Somalia. The stadium, Somalia's largest soccer facility, had been under control by Islamic extremist Shabab militants for the past two years until they withdrew from the capital more than a week ago. (Photo by John Moore/Getty Images)

Thousands of species of amphibians are endangered and hundreds have already disappeared, but in recent years, a team of scientists and conservationists have re-discovered some of these “lost” species and uncovered previously unknown varieties. Here: Miniature glass frog. (Photo by Robin Moore)

Labourers who work nearby nap on a road as cars drive past in Chongqing Municipality, July 23, 2013. (Photo by Reuters/Stringer)

Philadelphia Phillies Ben Francisco reacts after being hit in the head with a pitch by Cincinnati Reds Logan Ondrusek during the MLB National League Division Series baseball playoffs in Philadelphia, Pennsylvania, United States in this October 8, 2010 file photo. (Photo by Tim Shaffer/Reuters)