Kurdish pesh merga troops fire at Islamic State positions as they move toward the Iraqi town of Badana Pichwk on Monday morning, October 17, 2016. Kurdish forces began Monday advancing on a string of villages east of Mosul, the start of a long-awaited campaign to reclaim Iraq's second-largest city from the Islamic State, which seized it more than two years ago, officials said. (Photo by Bryan Denton/The New York Times)

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)

An actor performs during the show “Paris de Nuit” in Santiago, Chile, 20 September 2016. The show is a combination of cabaret and circus, produced by the Recirquel Contemporary Circus Company from Budapest, and will be performed at the Mapocho Cultural station from 20 to 25 September. (Photo by Mario Ruiz/EPA)

Men play cricket in Kabul, Afghanistan, 16 September 2021. A humanitarian crisis and alleged widespread human rights violations are among the top challenges Afghanistan faces a month after the Taliban's lightning-fast capture of Kabul. The economic crisis threatened to push 97 percent of the 40 million people into poverty by mid-2022, the United Nations has warned. (Photo by EPA/EFE/Stringer)

U.S. Air Force Major Paul “Loco” Lopez performs in an F-22 Raptor during the AirPower Over Hampton Roads JBLE Air and Space Expo at Joint Base Langley-Eustis, Virginia, U.S. May 18, 2018. (Photo by U.S. Air Force/Staff Sgt. Areca T. Bell/Handout via Reuters)

Ximena Rivero of Peru competes in the South American Pole Dance Championship in Buenos Aires November 24, 2014. Participants from throughout South America will be vying for the top spots in the two-day competition, with the winners qualifying for the 2015 World Pole Dance Championship in Hong Kong. (Photo by Enrique Marcarian/Reuters)

A porter stands at the bottom of the Illimani mountain, on the outskirts of La Paz, Bolivia, April 16, 2016. For years, Lydia Huayllas, 48, has worked as a cook at base camps and mountain-climbing refuges on the steep, glacial slopes of Huayna Potosi, a 19,974-foot (6,088-meter) Andean peak outside of La Paz, Bolivia. But two years ago, she and 10 other Aymara indigenous women, ages 42 to 50, who also worked as porters and cooks for mountaineers, put on crampons – spikes fixed to a boot for climbing – under their wide traditional skirts and started to do their own climbing. (Photo by David Mercado/Reuters)

Iraqi soldiers from 9th Armoured Division give drops of water to a dehydrated child rescued earlier by soldiers at the frontline, during the ongoing fighting between Iraqi forces and Islamic State militants near the Old City in western Mosul, Iraq June 13, 2017. (Photo by Erik De Castro/Reuters)