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)

Students pose for a pictures taken by their friends during spring break on the beach in the resort city of Cancun, Mexico, February 27, 2009. (Photo by Israel Leal/AP Photo)

A woman walks past graffiti on a wall in the Williamsburg neighborhood of the borough of Brooklyn, in New York, September 16, 2014. The picture was taken through car window with raindrops. (Photo by Shannon Stapleton/Reuters)

Women perform a pole dancing routine during the national day celebration of “Urban Pole” dance along a street in Monterrey, Mexico, on June 9, 2013. (Photo by Daniel Becerril/Reuters)

A newborn baby pangolin climbs the walls of a cage in Bangkok, Thailand April 20, 2011. The Thai custom office showed 175 pangolins they found hidden in a truck heading into Bangkok. (Photo by Damir Sagolj/Reuters)

A hostess sits at a restaurant with paintings depicting Thailand's King Bhumibol Adulyadej hanging on a wall in Bangkok, Thailand, June 6, 2016. (Photo by Athit Perawongmetha/Reuters)

A dog trainer works with a previously abandoned dog at a police centre in Saltillo, Mexico March 4, 2016. Stray dogs are adopted by the police from a municipal anti-rabies centre and then trained to help the police patrol the streets, and search for drugs, explosives and weapons. (Photo by Daniel Becerril/Reuters)

A man helps a child to dress as Jawa, a character from the Star Wars movie series, during an event organised by Star Wars fan club Monterrey in Monterrey, Mexico, December 13, 2015. (Photo by Daniel Becerril/Reuters)