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)

Only the most intrepid urban explorers cross the tattered ruins of the old Iron Curtain to endure the excessive bureaucracy, military paranoia and freezing winds of the East to hunt for the ghosts of an empire. Rebecca Litchfield is one who couldn’t resist the haunting allure of the ruins of the Soviet Union.

My name is Jakub and I’m a painter, illustrator & concept artist who lives and work in Poland. My speciality is dark fantasy, character design, concept art and portrait. Since several years I work and paint digitally, but I never gave up traditional drawing and painting. For me the most important in my work, is create unique atmosphere and tell some kind of story through my creations.

“Sunward”. When the Mediterrenean Mantis opened its wings, It seemed very impressive at the sunshine... Photo location: Nicosia, Cyprus. (Photo and caption by Hasan Baglar/National Geographic Photo Contest)

Nimbus, the 2 month old clouded leopard cub, who was hand reared at the home of curator Jamie Craig. Photographed sitting in her hammock at Cotswold Wildlife Park, Burford, Oxfordshire, UK on September 2014. Jamie Craig the curator of the Cotswold Wildlife park has hand reared the baby clouded leopard in his family bathroom after he was rejected by his mother. Now two months old Nimbus is been fed a cat milk replacement diet by bottle and is given soft toys to play with. It is hoped that the leopard will re-join others at the park and eventually join their breeding program. (Photo by SWNS/ABACAPress)

Swiss pilot Bertrand Piccard prepares for a test flight of the solar-powered Solar Impulse 2 experimental aircraft in Payerne November 13, 2014. The aircraft, weighing 2.4 tons with a wingspan of 72 meters, is fitted with more than 17,000 solar cells. An attempt to fly around the world in stages using only solar energy will be made in 2015. (Photo by Ruben Sprich/Reuters)

A dog sits with a competitor dressed as Santa Claus before an annual charity Santa fun run in Loughborough, central England December 7, 2014. (Photo by Darren Staples/Reuters)

Vendors selling candied haws wait for customers at the Harbin Ice and Snow Festival in Harbin, China, January 4, 2016. The festival is open from Jan. 5 till Feb. 5, 2016, and is aimed at attracting both foreign and local visitors to experience the beauty of the ice and snow. (Photo by Wang Zhao/AFP Photo)