New Orleans police officers try to keep their heads down as they move in on a Black Panther headquarters during an exchange of gunfire in New Orleans on September 15, 1970. The shootout occurred as police moved in to make arrests on Tuesday morning following a series of incidents. (Photo by Jack Thornell/AP Photo)

Participants in costumes pose before a Halloween parade in Kawasaki, south of Tokyo, Japan on October 28, 2018. (Photo by Toru Hanai/Reuters)

French artist Christophe Guinet, also known as “Mr Plant”, works on his plant shoe creation “Wood”, part of the artistic project “Just Grow It”, in his art gallery in Marseille, November 25, 2014. Guinet transforms name-brand Nike sneakers, cult footwear for urban youth, into vegetable compositions, creating a collection of artwork with trainers modified with tree bark, foam and flowers. (Photo by Jean-Paul Pelissier/Reuters)

Culinary Specialist 2nd Class Jaqueline Rodriguez subdues a simulated suspect after being sprayed with oleoresin capsicum (OC) spray during security training aboard the amphibious dock landing ship USS Comstock (LSD 45). (U.S. Navy photo by Mass Communication Specialist 2nd Class Joseph M. Buliavac/Released). May 10, 2011

The endangered kea is the world’s only alpine parrot, and one of the most intelligent birds. They show no fear of humans and are thieves and pranksters. The parrot is seen in the Whakaari conservation area, near Glen Orchy in the Otago region of New Zealand, a place where historic huts and mining relics are surrounded by stunning mountains covered in tussock. (Photo by Murdo MacLeod/The Guardian)

Cars slowly move along a bridge in traffic jam in central Moscow, Russia on December 11, 2018. (Photo by Yuri Kadobnov/AFP Photo)

The northern lights, or aurora borealis, illuminate the sky over Flakstad beach on Lofoten Islands in the Arctic Circle on September 5, 2017. (Photo by Jonathan Nackstrand/AFP Photo)

A tower belonging to the Abengoa solar plant at the Solucar solar park is seen in Sanlucar la Mayor, Spain on October 1, 2018. (Photo by Marcelo del Pozo/Reuters)