Coloured X-ray of a barn owl. A physicist has used X-ray to create an extraordinary collection of artwork. Arie van't Riets pictures reveal birds, fish, monkeys and flowers in an incredible new light. The 66-year-old, from Bathmen in the Netherlands, began X-raying flowers as a means to teach radiographers and physicians how the machine worked. But after adding a bit of colour to the pictures, the retired medical physicist realised the potential for an exciting new collection of art. (Photo by Arie van't Riet/Barcroft Media)

A protester wearing improvised protective headgear walks away from a cloud of tear gas on July 18, 2021 in Bangkok, Thailand. Student protesters called for a demonstration demanding the resignation of Thailand Prime Minister Prayuth Chan-o-Cha, despite a ban on gatherings because of the country's current Covid-19 outbreak, and folded a demand for better action in combating the virus into their demands. (Photo by Sirachai Arunrugstichai/Getty Images)

Emma Raducanu of Great Britain hits a return to Belinda Bencic of Switzerland during their quarterfinals round match on the tenth day of the US Open Tennis Championships the USTA National Tennis Center in Flushing Meadows, New York, USA, 08 September 2021. The US Open runs from 30 August through 12 September. (Photo by Justin Lane/EPA/EFE)

Lava flows from an eruption of a volcano on the Reykjanes Peninsula in Iceland on March 28, 2021. A week on, big crowds of Sunday hikers flocked to the Fagradalsfjall area to see up close Iceland's latest volcano eruption, as the gentle lava flow allowed people to get close to he eruption some 40 km west of Iceland's capital Reykjavik. (Photo by Halldor Kolbeins/AFP Photo)

People walk down a makeshift modeling runway as they take a break from marching during the Brooklyn Liberation's Protect Trans Youth event on June 13, 2021 in the Brooklyn borough in New York City. Brooklyn Liberation organized a march and rally as an emergency action response to legislation to restrict trans rights across 34 states. According to the Human Rights Campaign, there have been over 250 bills introduced in state legislatures aimed at the LGBTQ community in 2021. (Photo by Michael M. Santiago/Getty Images)

In this Thursday, February 14, 2019, photo, a Transformer's Bumblebee mascot helps a woman carries paper bags at a shopping mall in Handan in north China's Hebei province. U.S. and Chinese envoys are holding a second day of trade talks after the top economic adviser to President Donald Trump said he has yet to decide whether to go ahead with a March 2 tariff increase on imports from China. (Photo by Chinatopix via AP Photo)

In this Tuesday, March 12, 2019 photo, a visitor takes part in an immersive experience showing visitors how dogs see from inside the head of a dog at the California Science Center in Los Angeles. A new exhibit at a Los Angeles museum examines the relationship between dogs and humans and explores why the two species seem to think so much alike and get along so well. “Dogs! A Science Tail” opens Saturday, March 16, 2019, at the California Science Center. (Photo by Richard Vogel/AP Photo)

The Malabar Giant squirrel – double the size of their grey relatives and measuring up to 36 inches (91.5 cm) from head to tail – lives deep in the forests of India. The athletic animals can leap an incredible 20 feet (6 m) between trees. Photographer Kaushik Vijayan, 39, snapped the animals in their native habit to produce these stunning images. Kaushik, from Kerala State, India, said: “Up until that point I had never heard about a squirrel like that or seen one. The sight was an absolute feast for my eyes. The squirrels fascinated me and I got excited to capture this beauty on my camera”. (Photo by Kaushik Vijayan/South West News Service)