Planes land in fog at Heathrow Airport, west London, as heavy fog covers a many parts of the south east, on April 1, 2014. (Photo by Steve Parsons/PA Wire)

A dejected German Grenadier carrying a machine gun on his shoulder in front of a building on fire during the German retreat in Russia. (Photo by Keystone/Getty Images). 1944

Amateur astronomer Bill Snyder has been involved with astrophotography since 2007. Photo: The Cygnus Wall is in the southern area of NGC7000 also known as the North America Nebula. It is approximately 1800 light years from Earth, and is in the constellation Cygnus. The Wall is an energized shock front and contains the most concentrated star formations in the nebula. The size of the North America Nebula is about 4 full moons. (Photo and caption by Bill Snyder)

African migrants stranded in Costa Rica walk near garbage on the Inter-American highway at the border between Costa Rica and Nicaragua, in Penas Blancas, Costa Rica, September 8, 2016. (Photo by Juan Carlos Ulate/Reuters)

Two Scottish shorthair cats dressed with red hats are pictured during a cat exhibition in Bishkek, on October 16, 2016. Cat lovers from Kyrgyzstan, Kazakhstan and Uzbekistan took part in the exhibition. (Photo by Vyacheslav Oseledko/AFP Photo)

Alpine Skiing, FIS Alpine Skiing World Cup, Men's Parallel Giant Slalom, Alta Badia, Italy on December 19, 2016. Hostesses take a bath in a Jacuzzi pool during the race. (Photo by Stefano Rellandini/Reuters)

This July 2014 image provided by the Bureau of Land Management shows the interior of the Natural Trap Cave in north-central Wyoming. The cave holds the remains of tens of thousands of animals, including many now-extinct species, from the late Pleistocene period tens of thousands of years ago. Scientists have resumed digging for the first time in more than 30 years. (Photo by AP Photo/Bureau of Land Management)