A man walks his dog as the sun sets in a park in Frankfurt, Germany, Monday, September 18, 2017. Cool damp weather is set to continue in this part of Germany for the next few days with temperatures in the mid teens Celsius. (Photo by Michael Probst/AP Photo)

Sally Rand dances on a beach in St. Petersburg, Florida, February 17, 1936. (Photo by AP Photo)

In this Tuesday, March 20, 2018 photo, a Vampire Bat drinks bovine blood in the Criaturas de la Noche (Creatures of the Night) Bat House, the Audubon Zoo's new night house in New Orleans. The various species are all from Central and South America, and the building's interior simulates an abandoned warehouse set up to protect Mayan artifacts during a dig. (Photo by Gerald Herbert/AP Photo)

The sun rises over St Mary's Lighthouse in Whitley Bay on the Northumberland coast as a flock of Lapwing seabirds fly past on Wednesday, September 30, 2015. (Photo by Owen Humphreys/PA Wire)

A picturesque supercell formation in the northwest of Booker, Texas from June 2013. (Photo by Mike Olbinski/Barcroft Media)

Sydney resident Virginia Maddock watches the supermoon rise off the Sydney beachside suburb of Wanda, August 10, 2014. Sunday’s moon was at its closest approach to Earth, appearing bigger and brighter than any other moon this year. The moon was 221,765 miles away and looked 16 percent larger and 30 percent brighter than usual. (Photo by Jason Reed/Reuters)

The moon illuminates the snow-covered Concordia, the confluence of the Baltoro and Godwin-Austen glaciers, near the world's second highest mountain the K2 (8,000 meters) in the Karakoram mountain range in Pakistan September 6, 2014. While other parts of Pakistan and northern India were flooded, Concordia in the Karakoram mountain range was covered with a seasonally unusual amount of snow. Geographically, Pakistan is a climbers paradise. It rivals Nepal for the number of peaks over 7,000 meters and is home to the world's second tallest mountain, K2, as well as four of the world's 14 summits higher than 8,000 meters. (Photo by Wolfgang Rattay/Reuters)

“DC3 Wreck”. A capture of a US military DC3 plane wreck at the southern black beach in Iceland. Photo location: Iceland. (Photo and caption by Naian Feng/National Geographic Photo Contest)