Women take part in Glowork exhibition in Riyadh, Saudi Arabia on September 28, 2017. (Photo by Faisal Al Nasser/Reuters)

David Goffin of Belgium meets a koala during a promotional event for the Australian Open tennis tournament at Melbourne Park on January 17, 2018. (Photo by Fiona Hamilton/Reuters/Tennis Australia)

A Southwest Airlines jet takes off from Reagan National Airport with a thunderhead to the east on June 20, 2017 in Alexandria, VA. (Photo by Jonathan Newton/The Washington Post)

Coulpe in bed, secret lover hiding. (Photo by Peter Cade/Getty Images)

The sky looked on fire this morning, as it made the clouds glow red, just before sunrise at Peterborough Rowing Lake, in Nene Park, UK on January 18, 2017. (Photo by Paul Marriott/Rex Features/Shutterstock)

In this handout photograph received from Sumukha J.N on December 15, 2016, the newly-discovered spider Eriovixia Gryffindori sits on a leaf in the Kans in India's Western Ghats. (Photo by Sumukha J.N./AFP Photo)

The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)

A passenger (L) gets inside a decorated matatu as other passengers wait for it to fill at night in the streets of Nairobi, Kenya, 24 March 2018. The Matatu culture is very big in Kenya, the minibuses are decorated with colorful graffiti inside and outside and most of them are equipped with TV screens, high-speed internet, and power sockets. (Photo by Daniel Irungu/EPA/EFE)