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)

Qiandao Lake (Chinese: 千島湖, lit. Thousand Island Lake), a man-made lake located in Chun'an County, Zhejiang, China, formed after the completion of the Xin'an River hydroelectric station in 1959. 1,078 large islands dot the lake and a few thousand smaller ones are scattered across it. The lake covers an area of 573 km² and has a storage capacity of 17.8 km³. The islands in the lake cover about 86 km²

A man carries a block of ice left behind by a hailstorm in Sao Paulo, Brazil, on May 19, 2014. After the severe overnight hailstorm a layer of hailstones as deep as 20 centimeters covered streets and parks, drawing people to make snowmen and play in the ice, an unusual scene to the city. (Photo by Nelson Antoine/AP Photo)

“Thor Heyerdahl (October 6, 1914, Larvik, Norway – April 18, 2002, Colla Micheri, Italy) was a Norwegian ethnographer and adventurer with a background in zoology and geography. He became notable for his Kon-Tiki expedition, in which he sailed 8,000 km (4,300 miles) by raft from South America to the Tuamotu Islands. All his expeditions are shown in the Kon-Tiki Museum, Oslo”. – Wikipedia

Photo: Norwegian anthropologist Thor Heyerdahl with a model of the balsa raft “Kon-Tiki” on which he drifted 4,300 miles from Peru to the Tuamotu Islands, proving his theory that Polynesia could originally have been populated by South Americans. (Photo by Express/Express/Getty Images). 1950

Army soldiers prepare a military elephant for the parade during a rehearsal for Sri Lanka's 68th Independence day celebrations in Colombo, February 2, 2016. (Photo by Dinuka Liyanawatte/Reuters)

Penitent Jerry Mazon, 9, wears his “Morions” mask while playing with his baby brother during Holy Week celebrations in Mogpog, Marinduque in central Philippines March 22, 2016. (Photo by Erik De Castro/Reuters)

Cocoa pods are seen on the ground at a farm in Ile-Oluji village in Ondo state, southwest Nigeria March 29, 2016. (Photo by Akintunde Akinleye/Reuters)

Myanmar revellers take part in celebrations on the fifth and last day marking Thingyan, a water festival which brings in the country's new year, in Yangon on April 16, 2016. The Buddhist festival of water pouring symbolizes spiritual cleansing and begin the new year free from worldly impurities with celebrants devoting the four days of Thingyan in merry making of water dousing until the eve of new year. (Photo by Romeo Gacad/AFP Photo)