A tourist walks inside the Ice Palace glacier hollow at Hintertux glacier, located at around 3250 meters above sea level, in Zillertal, Austria, 02 March, 2016. The hollow's temperature remains constant at 0 degrees Celsius, in summer and winter alike, and is also used by the University of Innsbruck for scientific research projects. (Photo by Lisi Niesner/EPA)

Models dance during the presentation of Stella McCartney's Spring-Summer 2017 ready-to-wear fashion collection presented Monday, October 3, 2016 in Paris. (Photo by Francois Mori/AP Photo)

A passenger aircraft passes over a residential house as it prepares to land at London Heathrow Airport in west London on October 17, 2016. Britain's government is considering whether to approve a third runway at Heathrow or expand air capacity in southeast England at another airport such as London Gatwick. (Photo by Daniel Leal-Olivas/AFP Photo)

A mahout leads an elephant calf to the river Tunga for bathing at the Sakrebailu Elephant Camp in Sakrebailu in the southern state of Karnataka, India, November 12, 2016. (Photo by Abhishek N. Chinnappa/Reuters)

Women play soccer as the Tungurahua volcano spews a column of ash during an eruption in Huambalo, Ecuador, Saturday, March 5, 2016. Tungurahua is 16,480 feet (5,023 meters) high and has been active since 1999. (Photo by Dolores Ochoa/AP Photo)

Children are engulfed by foam during the Bubble Show event in Beijing, China, Sunday, June 26, 2016. Thousands of residents enjoy colored foam churned out by machines along a running track at the event designed for children and parents' interaction. (Photo by Ng Han Guan/AP Photo)

A monument to the character of Darth Vader from "Star Wars", which was rebuilt from a statue of Soviet state founder Vladimir Lenin, is seen in Odessa, Ukraine, October 23, 2015. The Internet Party of Ukraine's main candidate, a person named for the legendary "Star Wars" villain Darth Vader, campaigned in Odessa, cruising through town on a black van to the sound of Imperial March from "Star Wars" saga. (Photo by Yevgeny Volokin/Reuters)

A guide dangles a live chicken in front of a crocodile in the village of Bazoule, Burkina Faso, December 4, 2015. The villagers believe the crocodiles that live there are sacred. (Photo by Joe Penney/Reuters)