Street musicians with their faces covered with animal masks play to earn some money in central Vienna, Austria, November 8, 2015. (Photo by Vasily Fedosenko/Reuters)

The crowd watches as stunt pilots Melissa Pemberton, Jurgis Kairys and Skip Stewart of The Immortals fly past pyrotechnics as they perform at The Australian International Airshow on March 1, 2015 in Avalon, Australia. (Photo by Scott E. Barbour/Getty Images)

“Don't Leave Any Food On Your Plate”. The giraffes at Nairobi's Giraffe Manor are totally at home with humans. They will eat out of your hand, or even off your plate. Photo location: Giraffe Manor, Nairobi, Kenya. (Photo and caption by Gavin Werbeloff/National Geographic Photo Contest)

A villager pours pesticide from a bucket as Mount Sinabung spews ash at Kebayaken village in Karo district, Indonesia's North Sumatra province, on December 4, 2013. The country has ordered the evacuation of 15,000 residents near the active volcano. (Photo by Roni Bintang/Reuters)

A Tibetan man stirs butter tea made for the arriving guest during the function organised to mark Losar or the Tibetan New Year at a Tibetan Refugee Camp in Lalitpur February 19, 2015. Tibetans across the world marked the arrival of the New Year with prayers and festivities. (Photo by Niranjan Shrestha/AP Photo)

In this Wednesday, July 23, 2014 file photo, Omaha photographer Lane Hickenbottom photographs the night sky in a pasture near Callaway, Neb. With no moon in the sky, the Milky Way was visible to the naked eye. More than one-third of the world’s population can no longer see the Milky Way because of man-made lights, according to a scientific paper by Light Pollution Science and Technology Institute's Fabio Falchi and his team members, published on Friday, June 10, 2016. (Photo by Travis Heying/The Wichita Eagle via AP Photo)

Tourists take a panoramic view of Kuala Lumpur from a skybox during a media preview at Kuala Lumpur Tower in Kuala Lumpur, Malaysia, 05 May 2016. Skybox, 421 metres above ground level will be the latest tourists attraction at Kuala Lumpur Tower, the 7th tallest freestanding tower in the world. (Photo by Ahmad Yusni/EPA)

A street performer dressed up as a waiter performs for at Marques de Larios street in downtown Malaga, Spain, July 4, 2016. (Photo by Jon Nazca/Reuters)