Shanghai-based artist Hong Yi, also known as Red, used 750 pair of socks to create a rather unusual sock portrait of famous Chinese film director Zhang Yimou. Yi, which is famous for her Coffee Stain Portrait, spent over three weeks on the project and used black, white and grey socks. (Photo by Ohiseered.com)

This undated image provided by World View shows World View capsule and balloon spacecraft that will rise to 100,000 feet above Earth for passengers to see the curvature of the planet and the blackness of space. Space tourism companies are employing designs including winged vehicles, vertical rockets with capsules and high-altitude balloons. While developers envision ultimately taking people to orbiting habitats, the moon or beyond, the immediate future involves short flights into or near the lowest reaches of space without going into orbit. (Photo by World View via AP Photo)

Thai Princess Bajrakitiyabha (R) and Princess Sirivannavari Nariratana take part in the funeral procession for the late Thai king Bhumibol Adulyadej in Bangkok on October 26, 2017 A sea of black- clad mourners massed across Bangkok' s historic heart early on October 26 as funeral rituals began for King Bhumibol Adulyadej, a revered monarch whose passing after a seven- decade reign has left Thailand bereft of its only unifying figure. (Photo by Damir Sagolj/Reuters)

In this February 20, 2018 photo, fair vendor Noelia Flores holds up a black backdrop behind a small statue of an “Ekeko”, the god of prosperity, for a portrait at her booth during the annual Alasita Fair in La Paz, Bolivia. Every year, thousands of Bolivians head to the feast of Alasitas that is held in his honor to buy miniature cars, houses and toy dollar bills symbolizing their dreams of prosperity. (Photo by Juan Karita/AP Photo)

In this February 22, 2018 photo, a couple looks at a bag made out of Venezuelan Bolivars in La Parada, Colombia, on the border with Venezuela. Each collector item produced by Richard Segovia, sitting at the table, fetches between $10 and $15 – a huge markup from the pennies that bolivars retrieve on Venezuela's black market. (Photo by Fernando Vergara/AP Photo)

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)