A supporter of the Houthi movement attends a rally marking the birth anniversary of Prophet Mohammed, in Sanaa, Yemen December 11, 2016. (Photo by Khaled Abdullah/Reuters)

In this photograph taken on February 18, 2016, Pakistani children ride on swings in the predominantly Pashtun Korangi District of Karachi. In a rundown district of Karachi, Rabia balks at a neighbour's proposal to vaccinate her children, demonstrating one of the biggest hurdles to eradicating polio in Pakistan by the end of the year: confused and frightened parents. (Photo by Asif Hassan/AFP Photo)

A Hindu holy man or Sadhu walks back to his ashram after taking a dip at Sangam, confluence of Ganges river, Yamuna river and mythical Saraswati river in Allahabad, India, Thursday, August 4, 2016. (Photo by Rajesh Kumar Singh/AP Photo)

Gliding past the planet Jupiter, the Cassini spacecraft captures this awe inspiring view of active Io, Jupiter's third largest satellite, with the largest gas giant as a backdrop, offering a stunning demonstration of the ruling planet's relative size, April 20, 2001. The Cassini spacecraft itself was about 10 million kilometers from Jupiter when recording the image data. (Photo courtesy of NASA/Newsmakers)

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)

Indian dancers paint their body like tigers as they perform a Tiger dance during the International day of the Tiger in Calcutta, India, July 29, 2015. Students of Calcutta are taking part in an awareness campaign aiming to draw attention to the threats that tigers face due to habitat loss and poaching. (Photo by Piyal Adhikary/EPA)

A sacrificial bull decorated for sale stands at its feed trough at the animal market on the outskirts of Islamabad, Pakistan, September 22, 2015. Muslims across the world are preparing to celebrate the annual festival of Eid al-Adha or the Feast of the Sacrifice, which marks the end of the annual haj pilgrimage, by slaughtering goats, sheep, cows and camels in commemoration of the Prophet Abraham's readiness to sacrifice his son to show obedience to Allah. (Photo by Faisal Mahmood/Reuters)

(L-R) A man nicknamed "Barcelona", Alexey Bolotov and Alexey Jakushin drink vodka as they travel by a pioneer motorised railcar on their way to Kalach, Sverdlovsk region, Russia October 18, 2015. The "pioneer," a light auxiliary rail vehicle, is a popular form of transport among people who live along the Alapayevsk railway. In a remote corner of the Urals region at the end of a narrow-gauge railway is Kalach, population about a dozen. Three decades ago 600 people called the village home, but the local forestry industry suffered as the former Soviet Union imploded and people moved away in search of work. In Kalach today there are no telephones, no mobile reception and only a few hours of electricity a day. (Photo by Maxim Zmeyev/Reuters)