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)

A child working at Ship breaking yard in Chittagong, Bangladesh on November 14, 2014. (Photo by Pascal Mannaerts/Alamy Stock Photo)

Indian students smear coloured powder during an event to celebrate the Hindu festival of Holi in Kolkata on February 26, 2018. Holi, the popular Hindu spring festival of colours is observed in India at the end of the winter season on the last full moon of the lunar month, and will be celebrated on March 1 this year. (Photo by Dibyangshu Sarkar/AFP Photo)

People wait in line to pay their last respects to the late Fidel Castro in Havana, Cuba, Monday, November 28, 2016. Cuba's government has declared nine days of national mourning following Castro's death on Nov. 25. (Photo by Fernando Medina/AP Photo)

Somali couple Mohamed Noor (L) and Huda Omar pose for a photograph at their makeshift home during their wedding ceremony in Mogadishu's Rajo camp, Somalia August 17, 2016. Having met two years ago, the pair have just married at Rajo camp, where some 400 families live. Most, like Noor's parents, came here in the early 1990s to flee famine. (Photo by Feisal Omar/Reuters)

Buddhist monks take shelter under a tarpaulin sheet to protect themselves from the rain as they attend the birthday celebrations of the Tibetan spiritual leader the Dalai Lama (unseen) at Drepung Loseling Monastery in Mundgod, in the southern state of Karnataka, India, July 6, 2016. (Photo by Abhishek N. Chinnappa/Reuters)

Annabelle, 13, and her sister Estelle, 10, both artistic gymnasts from Borna, hang from the rings during their training, ahead of the Special Olympics World Games Berlin 2023, the world's largest sports movement for people with intellectual disabilities, at the Federal base for competitive gymnastic artistics in Chemnitz, Germany on May 6, 2023. (Photo by Annegret Hilse/Reuters)

Children play football in Bujumbura, Burundi on March 19, 2015. (Photo by Carl de Souza/AFP Photo)