Seven-year-old Mimi Meade winces from the sting as Dr. Richard Mulvaney inoculates her April 26, 1954 in McClean, Va., with the new Salk polio vaccine. Mrs. John Lucas, a registered nurse, holds Mimi's arm steady as she gets one of the first injections of the countrywide test. (Photo by Harvey Georges/AP Photo)

Mongolian Chinese performs a traditional Chinese dance in front of the Olympic Rings located near the National Stadium, the main stadium for the 2020 Tokyo Olympic Games in Tokyo, Japan July 29 2021. (Photo by Androniki Christodoulou/Reuters)

A man fires a weapon as he dances during a traditional excursion near the western Saudi city of Taif, August 8, 2015. Saudis usually party in such excursions as they celebrate weddings or graduations. (Photo by Mohamed Al Hwaity/Reuters)

Courtney Stodden attends the finale of “Celebs Go Dating” TV show filming at Dirty Martini in London, England on July 26, 2017. (Photo by Beretta/Sims/Rex Features/Shutterstock)

Soap Bubble Structures by Kym Cox. Bubbles optimise space and minimise their surface area for a given volume of air. This phenomenon makes them a useful tool in many areas of research, in particular, materials science and “packing” – how things fit together. Bubble walls drain under gravity, thin at the top, thick at the bottom, which interferes with travelling lightwaves to create bands of colour. Black spots show the wall is too thin for interference colours, indicating the bubble is about to burst. (Photo by Kym Cox/2019 Science Photographer of the Year/RPS)

Santa, a dog abandoned two days before Christmas, is looked after by Charlene Gunner at Battersea Dogs and Cats Home on December 27, 2012 in London, England. The home was founded 150 years ago and has rescued, reunited and rehomed over three million dogs and cats. The average stay for a dog is just 28 days although some stay much longer. Around 550 dogs and 200 cats are provided refuge by Battersea at any given time. (Photo by Peter Macdiarmid)

Injured horses huddle together in Oklahoma City on Monday. (Photo by Chris Landsberger/The Oklahoman)

A giant panda cub is pictured in an incubator at the Ya'an Bifengxia Giant Panda Breeding and Research Center in Ya'an city, southwest China's Sichuan province, 21 August 2015. Ten tiny panda cubs made their first public appearance at China's Ya'an Bifengxia Giant Panda Breeding and Research Center in southwestern Sichuan province on Friday (21 August 2015). All of the ten giant pandas were born in 2015. The oldest of them is just two month old, while the youngest one was born a week ago. This marks the first time they were put together as a group since they were born. (Photo by Imaginechina/Splash News)