A demonstrator is detained by police officers during a protest in Hong Kong, China on August 31, 2019. Hong Kong police fired tear gas and water cannons and pro-democracy protesters threw petrol bombs in the latest in a series of chaotic clashes that have plunged the Chinese-ruled city into its worst political crisis in decades. (Photo by Kai Pfaffenbach/Reuters)

Alien-themed decorations are seen at the Alien Research Center in Hiko, September 19, 2019. Scores of UFO enthusiasts converged on rural Nevada for a pilgrimage of sorts to the U.S. installation known as Area 51, long rumored to house government secrets about alien life, as law enforcement officials beefed up security around the military base. (Photo by Jim Urquhart/Reuters)

Zombie Punk stands for a photo during the International tattoo convention at Tobacco Dock in east London, Friday, September 27, 2019. (Photo by Aaron Chown/PA Wire Press Association via AP Photo)

Ukrainian serviceman fires with a heavy machine gun during a combat with Russia-backed separatists on the front line near Gorlivka, Donetsk Region on September 28, 2019. (Photo by Anatolii Stepanov/AFP Photo)

Graduates dance as they take part in a “Last school bell” ceremony at a school in Minsk, Belarus on May 30, 2018. (Photo by Vasily Fedosenko/Reuters)

Members of the China Disabled People’s Performing Art Troupe take part in the thousand-hand Bodhisattva dance in Mississauga, Canada on November 8, 2018. (Photo by Zou Zheng/Xinhua News Agency/Barcroft Images)

A swarm of starlings flies over the Altare della Patria monument (Unknown soldier) in the city centre of Rome during sunset, on November 27, 2018. (Photo by Vincenzo Pinto/AFP Photo)

Split-view of a killer whale at sunrise off the coast of Northern Norway. At least half of the world’s killer whale populations are doomed to extinction due to pollution of the oceans, a new study says. (Photo by Audun Rikardsen/Science)