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)

Riders pray before competing at a rodeo event in Monte Negro, south of the Amazon basin, Rondonia state, Brazil on August 30, 2019. In recent years, Monte Negro has expanded as a key cattle town with a strong cowboy culture. (Photo by Carl De Souza/AFP Photo)

This week's full Moon as photographed from on board the International Space Station by NASA astronaut Jeff Williams on August 19, 2016. Jeff is currently Commander of the Space Station for the Expedition 48 crew. (Photo by Jeff Williams/NASA)

A woman jumps in the air as she poses for a photo during New Year celebrations in the Manhattan borough of New York, January 1, 2016. (Photo by Carlo Allegri/Reuters)

Harris & Ewing Inc. photographed people, events, and architecture, particularly in Washington, D.C., during the period 1905-1945. Photo: Tests of Curtiss Palne for Army, Single Control. Created by Harris & Ewing. Published in 1912.

A demonstrator wears a message on a t-shirt in Tahrir Square on May 27, 2011 in Cairo, Egypt. The ruling Supreme Council of the Armed Forces said that there would be no use of violence against protests dubbed “the Second Revolution of Anger” taking place in Cairo and other cities in Egypt. (Photo by Peter Macdiarmid/Getty Images)

A vendor (C) serves customers at a vegetable market as a commuter train passes in Jakarta October 2, 2015. Indonesia's high annual inflation rate cooled in September and should drop more by year-end, but it likely will be 2016 before the central bank can cut interest rates to help an economy growing at its slowest pace in six years. (Photo by Reuters/Beawiharta)

People play with foam at a water park in Yantai, Shandong province, China June 16, 2107. (Photo by Reuters/Stringer)