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)

Cormorant masters and boatmen prepare sea cormorants for the nights “Ukai” on July 2, 2014 in Gifu, Japan. In this traditional fishing art “ukai”, a cormorant master called “usho” manages cormorants to capture ayu or sweetfish. The ushos of River Nagara have been the official staff of the Imperial Household Agency of Japan since 1890. Currently six imperial fishermen of Nagara River conduct special fishing to contribute to the Imperial family eight times a year, on top of daily fishing from mid-May to mid-October. (Photo by Chris McGrath/Getty Images)

This greedy piglet was isolated from the rest of its litter by the farmer who named it Hitler after it tried to grab all the food at feeding time. (Photo by R J Lewis/Getty Images). 1942

“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

In this photo taken on Sunday, July 5, 2015, police officers walk along a giant poster to give an improved appearance, in downtown Ufa, Russia. Ufa will host SOC (Shanghai Cooperation Organization) and BRICS (Brazil, Russia, India, China and South Africa) summits July 7 to July 9, 2015. (Photo by Vadim Braydov/AP Photo)

A devotee dressed as Hindu Lord Shiva waits to participate in a parade during “Kumbh Mela” or the Pitcher Festival in Trimbakeshwar, India, August 18, 2015. The Kumbh Mela takes place four times every 12 years at four different river bank locations in India. (Photo by Danish Siddiqui/Reuters)