A picture made available on 17 July 2015 shows the bright line of the Milky Way above the old oaks at the Rogalin landscape Park in Rogalin village, near Poznan, on the night of 16 July 2015. (Photo by Lukasz Ogrodowczyk/EPA)

A member of the Revolutionary Armed Forces of Colombia (FARC) pose for a picture at a camp in the Colombian mountains on February 2005. (Photo by Frank Piasecki Poulsen)

Eleven-year-old Kelen loves to dance in the half-built rooms of the centre in Kabanga Refuge Centre, Tanzania, 2012. The rescue centres protect albino people from the vicious hunters who sell their body parts to witch doctors. Photojournalist Ana Palacios, 43, visited the centre in Tanzania three times between 2012 and 2016 to find out more about the plight of albino people. (Photo by Ana Palacios/Barcroft Images)

A person viewing the Northern lights over the lava landscape, Reykjanes Peninsula, Iceland. (Photo by Arctic-Images/Getty Images)

Women compare their bikini marks after sunbathing on a terrace to have the perfect bikini line (“marquinha” in Portuguese), at the Erika Bronze spa in Rio de Janeiro, Brazil, November 17, 2016. Women start arriving at the spa between 7am and 8am and will tan for approximately 3 hours. (Photo by Pilar Olivares/Reuters)

A navy diver storms into the gallery during a military display at Singapore's 52nd National Day celebrations at Marina Bay in Singapore August 9, 2017. (Photo by Edgar Su/Reuters)

Arctic treasure by Sergey Gorshkov (Russia). An arctic fox carries its egg trophy from a raid on a snow goose nest and heads for a suitable burial spot. Finalist 2017, Animal Portraits. (Photo by Sergey Gorshkov/2017 Wildlife Photographer of the Year)

A woman wearing a scarf to cover her face looks on as she waits for a passenger bus on a smoggy morning in New Delhi, India, November 8, 2017. The Great Smog of Delhi is an ongoing severe air-pollution event in New Delhi and adjoining areas in the National Capital Territory of India, in November 2017. Air pollution at this time peaked on both PM 2.5 and PM 10 levels. It has been reported as one of the worst levels of air quality in Delhi since 1999. (Photo by Saumya Khandelwal/Reuters)