Andrea Abarca, (C) leads an aerobics class in Los Guidos de Desamparados July 23, 2015. More than 300 women participated in a physical health program organized by Abarca, which aims to combat obesity and sedentary behavior in poor women living in a slum. The National Nutrition Survey shows that the Costa Rican population has 62.4 percent of adult men who are obese, while among women the percentage was 77.3, according to local media. (Photo by Juan Carlos Ulate/Reuters)

Club-goers dance at “Morning Gloryville” at the Ministry of Sound in south London August 11, 2015. Morning dance parties with names like “Morning Gloryville” and "Daybreaker" are gathering steam in cities across the world, giving rise to a movement known as “conscious clubbing”. Its founders aim to create the energy and community of electronic dance parties with fruit smoothies and coffee instead of the drugs and alcohol more common after nightfall. (Photo by Toby Melville/Reuters)

Zoo keeper Ross Poulter holds a White's Tree Frog in Edinburgh Zoo's new tropical forest zone on September 9, 2011 in Edinburgh, Scotland. The Brilliant Birds Exhibit which brings together beautiful and rare birds from all over the world is now more colourful and unusual, with the unveiling of the zoo's new tropical forest zone bringing together a collection of vertebrates, invertebrates and amphibians for the very first time. (Photo by Jeff J Mitchell/Getty Images)

A logometer used to determine the Titanic's speed is seen among artifacts recovered from the RMS Titanic wreck site at a press preview of a Titanic artifact auction at the Intrepid Sea, Air & Space Museum on January 5, 2012 in New York City. On April 11, 2012, the 100th anniversary of the maiden voyage of the Titanic, Guernsey's will auction the complete collection of more than 5,000 artifacts recovered from the Titanic wreck site. (Photo by Mario Tama/Getty Images)

The competition is run by Royal Observatory Greenwich sponsored by Insight Investment and in association with BBC Sky at Night Magazine. This year astrophotographers from 91 countries sent in more than 4,200 spectacular entries. Here: The Milky Way rises above an isolated lighthouse in Tasmania. Shot by James Stone of Australia. (Photo by James Stone/Astronomy Photographer of the Year 2018)

A reveller plays with tomato pulp during the annual Tomatina festival in Bunol, near Valencia, Spain on August 29, 2018. As every year on the last Wednesday of August, thousands of people visit the small village of Bunol to attend the Tomatina, a battle in which tons of ripe tomatoes are used as weapons. This year, a total of 145 tons of ripe tomatoes will be thrown between more than 22,000 participants. (Photo by Heino Kalis/Reuters)

Men are sent down into the sludge to clear the sewers in the Bangladeshi capital Dhaka on May 23, 2018. The people who do the work aren’t even given any protective clothing or goggles and have to dig out the clogged-up muck with a stick or their bare hands. (Photo by Rehman Asad/Barcroft Media)

For more than three years, Ukraine has been plagued by a conflict between the eastern secessionist territories and the Kiev government. Demonstrations by pro-Russian parties that oppose the current government first began in 2014 - and now, over 10,000 people have died, many of them civilians. These images portray a generation caught between war and peace. Many of them were born into the civil conflict dominating the country and are disorientated about their place in the world. Here: Youths during a party organised on a decommissioned bridge in Kiev. (Photo by Aude Osnowycz/The Guardian)