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)

“The Tonight Show” host Jimmy Fallon, center, exits the water during the Chicago Polar Plunge, Sunday, March 2, 2014, in Chicago. Fallon joined Chicago Mayor Rahm Emanuel in the event. (Photo by Andrew A. Nelles/AP Photo)

A sunflower “smiles” in a field in Tokyo on August 7, 2014. Some 20,000 sunflowers were enjoyed by visitors to the area this week. (Photo by Yoshikazu Tsuno/AFP Photo)

A homeless man wearing face masks to protect against coronavirus, waits to receive basic medial help from members of a group of volunteer doctors of the Dom Druzei (Home of Friends) NGO in Moscow, Russia, Wednesday, April 1, 2020. As Moscow goes into lockdown amid the coronavirus pandemic, thousands of homeless people have trouble receiving food, water and shelter as Russia's capital closes non-essential businesses, cafes and parks. (Photo by Pavel Golovkin/AP Photo)

A worker disinfects a mosque for coronavirus, in Peshawar, Pakistan, Thursday, April 2, 2020. The government imposed a nationwide lockdown to try to contain the outbreak of the virus. (Photo by Muhammad Sajjad/AP Photo)

Protesters march against the death in Minneapolis police custody of George Floyd, in the Manhattan borough of New York City, U.S., June 1, 2020. (Photo by Mike Segar/Reuters)

Rescue workers try to help a driver out of his car, after the vehicle was stuck over an alley in Wenzhou, Zhejiang province, August 4, 2014. The car rolled off the edge of a road after the driver was late to brake, according to local media. (Photo by Reuters/Stringer)

Italian disabled dancer Simona Atzori (top) performs, before a special audience with disabled athletes led by Pope Francis, in Paul VI hall at the Vatican October 4, 2014. (Photo by Tony Gentile/Reuters)