The Northern Lights glow green in a spectacular light show above a field of trees frozen solid with snow. (Photo by Jaak Sarv/Solent News & Photo Agency)

A woman covers her face as a fire burns in the middle of town during an anti-G20 protest on July 7, 2017 in Hamburg, Germany. Authorities are braced for large-scale and disruptive protests as Leaders of the G20 group of nations arrive in Hamburg for the July 7-8 G20 summit. (Photo by Leon Neal/Getty Images)

White lioness Azira lies in the cage with her three white cubs, on February 4, 2014. Zoo owner Andrzej Pabich says white lions often have defects that prevent giving birth, or the mother rejects her cubs, but Azira has been patiently feeding and caring for her little ones. (Photo by Czarek Sokolowski/Associated Press)

A fisherman is seen standing on a cliff edge at Cape Bank in La Perouse on February 20, 2011 in Sydney, Australia. The practice of fishing from rock platforms, cliffs and rocky outcrops is notoriously dangerous with many anglers per year being washed into the ocean by dangerous surf or unexpected large waves. Angling is often reported as the sport having the highest mortality rate on average due to fishermen drowning with rocking fishing contributing to a high number of these deaths. (Photo by Mark Kolbe/Getty Images)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

Gerald Herbert is a staff photographer for the AP based in New Orleans, Louisiana. Before that he was a staff photographer for the Washington Times, the New York Daily News and a freelancer for the AP in New Orleans, Boston and New York. Photo: A worker grooms away tracks after an alligator crossed through a sand trap on the 14th hole during the first round of the PGA Tour Zurich Classic golf tournament at TPC Louisiana in Avondale, La., Thursday, April 25, 2013. (Photo by Gerald Herbert/AP Photo)

June 21: “World War Z”. Brad Pitt battles zombie apocalypse in $170 million film by “Quantum of Solace” director Marc Forster. This publicity photo released by Paramount Pictures shows, center, Brad Pitt as Gerald Lane in a scene from the film, “World War Z”, from Paramount Pictures and Skydance Productions in association with Hemisphere Media Capital and GK Films. (Photo by Jaap Buitendijk/AP Photo/Paramount Pictures)