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)

Enthusiast dressed as zombies take part in the Zombie Walk event on September 14, 2019 in the eastern French city of Strasbourg, within the framework of the 12th edition of the European Fantastic Film festival, which runs from September 14 to 22. (Photo by Frederick Florin/AFP Photo)

“A Balinese man shows off his pride and joy, a fighting cock, while on a cigarette break after a morning’s work in nearby fields”. (Photo by Coltrane Koh/The Guardian)

In this January 23, 2015 photo, Guillermo Luna Martinez, 36, carries freshly painted piñatas representing Disney's Frozen snowman character Olaf downstairs to where his wife Elvia Vicente Albarran will use paper to craft the character's eyes, teeth, and distinctive tuft of hair, at the family's workshop in the Iztapalapa neighborhood of Mexico City. Though Luna and his wife have chosen to work in the family business, they plan to let their children, Guillermo, 10, and Melissa, 9, decide for themselves. “Who knows if the business will last forever”, said Luna, “I'd prefer that they study and get a career, for them to have a better future”. (Photo by Rebecca Blackwell/AP Photo)

A boy rides on a snow wagon towed by a robot dressed as a Teddy bear, which only moves forward by moving its legs, during the Ice and snow carnival at Taoranting park in Beijing February 9, 2015. (Photo by Kim Kyung-Hoon/Reuters)

People are seen in the crowd as Serbian Emir Kusturica & The No Smoking Orchestra performs during the third day of the Mexican musicial festival Vive Latino, at the Foro Sol in Mexico City, on March 29, 2014. (Photo by Alfredo Estrella/AFP Photo)

In this February 19, 2014 photo, a skate seller puts slices of skate into styrofoam boxes for shipment to customers around South Korea at a fish market in Mokpo, a port city on the southwestern tip of the Korean Peninsula. The aroma of one of southwestern South Korea's most popular delicacies regularly gets compared to rotting garbage and filthy bathrooms. And that's by fans. The unusual dish is typically made by taking dozens of fresh skate, a cartilage-rich fish that looks like a stingray, stacking them up in a walk-in refrigerator and waiting. Up to a month in some cases. (Photo by Ahn Young-joon/AP Photo)

Photos of Edward Snowden, a contractor at the National Security Agency (NSA), and U.S. President Barack Obama are printed on the front pages of local English and Chinese newspapers in Hong Kong in this illustration photo June 11, 2013. Snowden, who leaked details of top-secret U.S. surveillance programs, dropped out of sight in Hong Kong on Monday ahead of a likely push by the U.S. government to have him sent back to the United States to face charges. (Photo by Bobby Yip/Reuters)