Tank crew standing in front of M-4 tank, Ft. Knox, Kentucky, June, 1942. (Alfred Palmer/OWI/LOC)

World Champion Trials bike rider Jack Field of Australia poses after performing the highest backflip on a motorcycle ever recorded as he flips his motorbike upside down on the roof of Melbourne's Eureka Tower (297.3 metres) during a AUS-X Open media opportunity at Eureka Tower on May 22, 2019 in Melbourne, Australia. The largest international Supercross and action sports event in the world outside of the USA, the AUS-X Open will be held at Melbourne's Marvel Stadium on November 30 2019. (Photo by Scott Barbour/Getty Images)

Guests arrive at the red carpet for the movie “The Truth” (La Verite) presented in competition at the 76th Venice Film Festival, in Venice, Italy, August 28, 2019. (Photo by Yara Nardi/Reuters)

Two paddle boarders stop to watch the sunrise on a stormy morning in Sanibel, Fla., Thursday, August 15, 2019. (Photo by J. David Ake/AP Photo)

In this Thursday, October 3, 2019 photo, a female black bear sleeps with its tongue out high up in a Ponderosa pine tree near Clark Fork School in the Rattlesnake neighborhood of Missoula, Mont. The bear's cub, not pictured, was snoozing on a nearby branch. (Photo by Tommy Martino/The Missoulian via AP Photo)

A hummingbird is photographed during the National Orchid Exhibition at the Jose Celestino Mutis Botanical Garden in Bogota, Colombia Septermber 20, 2018. Picture taken September 20, 2018. (Photo by Luisa Gonzalez/Reuters)

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)