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)

Burlesque dancer and Lucha VaVoom co-founder Rita D'Albert gets dressed before the Lucha VaVoom “Night of the Vampire” performance in Los Angeles, California October 29, 2014. (Photo by Patrick T. Fallon/Reuters)

Wednesday March 8 marks International Women's Day, with festivals, concerts and exhibitions among the numerous events planned around the world to celebrate the achievements of women in society. The annual event has been held since the early 1900s and traditionally promotes a different theme each year, with this year's edition calling on people to #BeBoldForChange and push for a more gender-inclusive working world. Reuters photographers have been speaking with women in a range of professions around the world about their experiences of gender inequality. Here: Yolaina Chavez Talavera, 31, a firefighter, poses for a photograph in front of a truck at a fire station in Managua, Nicaragua, February 22, 2017. (Photo by Oswaldo Rivas/Reuters)

An iguana in Bali helped Julij Kopilović, age eight, from Slovenia, earn second runner-up in Amazing Animals. (Photo by Julij Kopilović/National Geographic)

Clouds gather as walkers pause atop a ridge in Mountain View, California January 7, 2016. (Photo by Noah Berger/Reuters)

Heidi Klum, dressed as a werewolf, performs a dance from Michael Jackson's "Thriller" video her 18th Annual Halloween Party at Moxy Times Square on Tuesday, October 31, 2017, in New York. (Photo by Evan Agostini/Invision/AP Photo)

Rush-hour in Russia means one thing for this daredevil: train surfing! The 19-year-old daredevil who goes by the name Kobzarro started train surfing aged 15 as a way of escaping an oppressive family life. Here Kobzarro can be seen balanced on top of a train as it speeds through the wintery Russian environment. Kobzarro is so dedicated to train surfing that she rarely gets inside a train. Even in winter she prefers to travel in this less conventional way. It has resulted in a few run ins with the law, but Kobzarro says it has never resulted in anything more serious than a fine, with many police officers even being interested in the train surfing community. (Photo by Caters News Agency)

A doctor performs surgery on an injured man with a part of an aluminium alloy fence through his chest after a car accident in Zhumadian, Henan province, China, September 15, 2014. The doctor managed to surgically remove the piece. (Photo by Reuters/Stringer)