A man pushes a tub carrying children as he gets them back home after school at a flooded area in Duchang, Jiangxi Province, China, June 27, 2016. (Photo by Reuters/Stringer)

The NASA Extreme Environment Mission Operations (NEEMO) 21 mission began on July 21 as an international crew of aquanauts splashed down to the undersea Aquarius Reef Base, located 62 feet below the surface of the Atlantic Ocean in the Florida Keys National Marine Sanctuary. The NEEMO 21 crew will perform research both inside and outside the habitat during a 16-day simulated space mission. During simulated spacewalks carried out underwater, they will evaluate tools and mission operation techniques that could be used in future space missions, including journeys to Mars. (Photo by Karl Shreeves/NASA)

Mamoni Mandal, member of the Rapid Action Force (RAF), attends a training session at a police training school in Kolkata April 15, 2007. (Photo by Parth Sanyal/Reuters)

A workman sweeping the highest sidewalk in the world, the 81st story of the Empire State Building, the world's tallest building, to the top of which the greatest dirigible “Los Angeles” will attempt to moor, New York, New York, early 1930s. This photo was made 1,248 feet above street level. (Photo by Adam Glickman/Underwood Archives/Getty Images)

Over the years a large population of grey herons have made an unlikely home in urban Amsterdam. Julie Hrudova documents how the birds integrate into city life. Here: Hundreds of herons come to the city during winter to find food and shelter. (Photo by by Julie Hrudova/The Guardian)

Models sit backstage during Dakar Fashion Week in the Senegalese capital, Friday June 30, 2017. The continent's fashion scene has grown steadily over the past two decades with Sub-Saharan Africa's apparel and footwear market now worth $31 billion, according to data by Euromonitor. (Photo by Finbarr O'Reilly/AP Photo)

People walk past a sculpture entitled “Reunion” by artist Sam Jinks at a preview of the Melbourne Art Fair in Melbourne on August 1, 2018. The sculpture is made of silicone, pigment, resin and human hair. (Photo by William West/AFP Photo)

A dog jumps into a swimming pool to retrieve a ball during the Chatsworth House Country Fair near Edensor, Britain on August 31, 2018. (Photo by Darren Staples/Reuters)