Internally displaced Syrian children stand at the entrance of their makeshift shelter that is an underground cave in Om al-Seer, southern Idlib countryside, Syria December 26, 2015. (Photo by Khalil Ashawi/Reuters)

ESA astronaut Samantha Cristoforetti on the International Space Station 3 February 2015 during her Futura mission. Samantha is living and working on the Station as part of the Expedition 42 crew. Picture released on February 10, 2015. (Photo by ESA/NASA)

Friends outside the convention center during opening day of the annual Comic-Con International in San Diego, California, United States July 21, 2016. (Photo by WENN/SIPA Press)

A girl reacts as she is tattooed during the third International Tattoo Week Rio 2016 festival in Rio de Janeiro, Brazil, January 22, 2016. (Photo by Pilar Olivares/Reuters)

Contorsionist Rich Miteku performs during the opening of the 41st Monte-Carlo International Circus Festival in Monaco on January 19, 2017. (Photo by Valery Hache/AFP Photo)

Internally displaced Syrian children who fled Raqqa city stand near their tent in Ras al-Ain province, Syria January 22, 2017. (Photo by Rodi Said/Reuters)

Janet Layug walks off stage during the Bikini International competition at the Greater Columbus Convention Center during the Arnold Sports Festival 2017 on March 4, 2017 in Columbus, Ohio. (Photo by Maddie Meyer/Getty Images)

A Sphynx cat at the 2017 Grand Prix Royal Canin international cat show at the Crocus Expo Exhibition Centre in Moscow, Russia on December 2, 2017. (Photo by Sergei Savostyanov/TASS/Barcroft Images)