Brain-on-a-chip. Dazzling in green and magenta this image shows the nerve fibres (in green) produced by neural stem cells (in magenta) as they grow on a synthetic gel. Captured by a technique known as confocal microscopy, the image is part of research shedding light on how tinkering with the environment can affect the way in which nerve fibres grow. (Photo by Collin Edington and Iris Lee/Massachusetts Institute of Technology/Wellcome Images)

“Aurora Hunters”. Photographers taking part in a photography tour on the Lofoten Islands in Norway, pull over on the side of the road to take a photo of their first ever Aurora Borealis after spotting it from their tour bus. Photo location: Rystad, Lofoten Islands, Norway. (Photo and caption by Mark Gee/National Geographic Photo Contest)

Japanese chorus girls appear to be drilling in military tactics atop their theater building as they perform salutes, June 30, 1937. The officer is from the Japanese regular army and says the girls display more rhythm in their drills than do the regular troops. (Photo by AP Photo)

Cyclists desperately try to keep their heavily-laden bicycles upright as they arrive at a market with baskets full of pineapples on August 23, 2018. The men travel up to 12 and a half miles with two baskets tied to the sides of their bikes, carrying between 50 and 100 pineapples to sell. Each of the bicycles is so heavily laden with fruit it is impossible for the men to actually ride their bikes, instead having to walk alongside them. When they arrive at the market place in Madhupur, Bangladesh, buyers will pay up to 30 Taka for a pineapple – the equivalent of around 28 pence. (Photo by Abdul Momin/Solent News & Photo Agency UK)

Women perform in the traditional “Morenada” dance during Carnival, in Oruro, Bolivia, Saturday, March 2, 2019. The unique festival features spectacular folk dances, extravagant costumes, beautiful crafts, lively music, and up to 20 hours of continuous partying with lots of tourists, drawing crowds of up people annually. (Photo by Juan Karita/AP Photo)

Elementary school sumo wrestlers compete in the sumo ring during the Wanpaku sumo-wrestling tournament in Tokyo, Japan July 30, 2017. (Photo by Kim Kyung-Hoon/Reuters)

Children attend a war safety awareness class conducted by civil defence members, in the rebel-controlled area of Maaret al-Numan town in Idlib province, Syria May 14, 2016. (Photo by Khalil Ashawi/Reuters)

A woman daubed in colours shakes her head to remove the coloured powder during Holi celebrations in Ahmedabad, India on March 18, 2022. (Photo by Amit Dave/Reuters)