The two Pulis Quastie and Gin-Gin run in the snow in their garden in Lautertal, southern Germany, Thursday, January 5, 2017. (Photo by Michael Probst/AP Photo)

Refugees and migrants try to find a place on an already full train headed for Serbia, near the city of Gevgelija, The Former Yugoslav Republic of Macedonia, on February 24, 2016. Refugees and migrants from Iraq and Syria continue to pass through Macedonia on their way to the European Union. (Photo by Georgi Licovski/EPA)

Demonstrators protest the shooting death of Alton Sterling near the headquarters of the Baton Rouge Police Department in Baton Rouge, Louisiana, U.S. July 9, 2016. (Photo by Jonathan Bachman/Reuters)

A damaged vehicle is seen next to the ring road, around Skopje, near the village of Stajkovci, Skopje, The Former Yugoslav Republic of Macedonia, 08 August 2016. At least 21 people have died and more than 100 are injured in the heavy rain storm that hit the Macedonian capital Skopje late Saturday night causing severe damage to the roads and house infrastructure. More than 80 vehicles were hit by landslides at Skopje's ring road. The highway remains closed. The government announced a 15-day state of emergency in the Skopje and Tetovo region. (Photo by Georgi Licovski/EPA)

“Strike Through The Mothership”. Every May for the last 3 years I have driven down to Tornado Alley to capture some amazing storms. This supercell held so much promise to drop a tornado but one small shift in the atmosphere and all that it produced was an extreme lightning show. Photo location: Broken Bow, Nebraska. (Photo and caption by Vanessa Neufeld/National Geographic Photo Contest)

A woman offers prayers by a road as a rickshaw puller transports passengers in Kolkata October 28, 2014. (Photo by Rupak De Chowdhuri/Reuters)

A P-51 Mustang named “Charlotte's Chariot” from the Southern Heritage Air Foundation flies past a cloud of smoke and fire from a nearby battle reenactment during the Wings Over Houston Airshow in Houston, on Saturday, November 1, 2014. Battle reenactments are part of the yearly show held at Ellington Airport. (Photo by Kar Hlava/AP Photo/Bay Area Citizen)

Wedges of an orange generate enough current and electrical juice – 3.5 volts – to power an LED. The fruit’s citric acid helps electrons flow from galvanized nails to copper wire in this 14-hour exposure. This image was published in September’s Visions of Earth, a trio of photos that appear in each issue of National Geographic. (Photo by Caleb Charland/National Geographic)