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)

Alex Plunkett, left, and Sean Hart, both of Arlington, Va., join hundreds participating in the annual International Pillow Fight Day on April 5. Massive pillow fights broke out on the Mall in Washington and in cities around the world. (Photo by Marvin Joseph/The Washington Post)

Parade-goers walk in the annual West Indian Day Parade on September 02, 2019 in the Brooklyn borough of New York City. The annual celebration of Caribbean culture is one of the largest of its kind and features dozens of floats and costumed participants that make their way down Flatbush Avenue. (Photo by Yana Paskova/Getty Images)

A member of Sisters of the Valley, a non-religious international group founded in 2014 which has pledged to spread the gospel of the healing powers of cannabis, who uses the moniker “Sister Bernardet” online and asked not to give her name for fear of reprisal, smokes a joint at the Sisters of the Valley's farm on the outskirts of a village in central Mexico on September 3, 2023. (Photo by Raquel Cunha/Reuters)

Police officers remove Extinction Rebellion activists blocking a main street outside the Health Ministry, during a protest demanding actions against climate change, in Madrid, on March 26, 2021. (Photo by Gabriel Bouys/AFP Photo)

Yanick Wasser of Switzerland jumps in the Mens Large Hill Individual competition during Day 2 of the FIS Ski Jumping World Cup at Lake Placid Olympic Jumping Complex on February 08, 2025 in Lake Placid, New York. (Photo by Al Bello/Getty Images)

A goat begs for food as people have a meal and beer at the Beichelstein-Alpe outdoor restaurant near Seeg, southern Germany, on March 27, 2017. (Photo by Karl-Josef Hildenbrand/AFP Photo/DPA)

A spectator shows off her green, white and gold eyelashes as the annual Saint Patrick's day parade takes place on March 17, 2018 in Dublin, Ireland. Dublin hosts the largest Saint Patrick's day parade in the world with a route spanning 2.5 km. The Irish annals for the fifth century date Patrick's arrival in Ireland in the year 432 with the patron saint of Ireland's remains believed to be buried at Down Cathedral in County Down. (Photo by Charles McQuillan/Getty Images)