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)

Peruvian surfer Domingo Pianezzi rides a wave with his alpaca Pisco at San Bartolo beach in Lima March 16, 2010. Pianezzi has spent a decade training dogs to ride the nose of his board when he catches waves, and now he is the first to do so with an alpaca. (Photo by Pilar Olivares/Reuters)

In this May 1, 2016 photo, a reluctant donkey is alternately pushed and pulled and enticed with carrots toward town hall in order to be dressed for the costume competition at the annual donkey festival in Otumba, Mexico state, Mexico. Otumba was an important donkey market during Spanish colonial times, standing at the crossroads of major roads leading to Mexico City, where the beasts pulled heavy loads and carried travelers. Today, however, farmers use tractors and pickup trucks, and the donkey population is in decline. (Photo by Rebecca Blackwell/AP Photo)

5-year-old Rina Kumari rubs her eye while cracking stones on the banks of Mahananda river in Siliguri, northeast India, March 5, 2005. Over 400 million people in India live below the internationally agreed poverty line (living on less than US $1 per day). According to estimates, several hundred thousand children work as labourers and beg on the streets in India. (Photo by Desmond Boylan/Reuters)

Rays from the rising sun shine through the foliage of trees as fog covers the ground near the Guckler Karoly Observatory in Budapest, Hungary, 02 January 2017. (Photo by Balazs Mohai/EPA)

Only 156 people remained in the tribe when Jan visited in Accham District, Nepal, January 2016. Hidden deep in the Himalayan forest is one of the world’s last enduring nomadic tribes who are resisting attempts to move them into permanent settlements. (Photo by Jan Moller Hansen/Barcroft Images)

Kashmiri vegetable vendors assemble at a floating market in the interiors of the Dal Lake in Srinagar April 17, 2012. (Photo by Danish Ismail/Reuters)

A man bathes in an ice hole in the Neva River St. Petersburg, Russia, Wednesday, February 10, 2021. The temperature in St. Petersburg is –15C ( 5 °F). (Photo by Dmitri Lovetsky/AP Photo)