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)

Nine year old girl Barsati reacts while walking on a tightrope in Mumbai on February 11, 2014. Barsati, and her younger brother Rajababu, (4) earn an average of around 2000 rupees (32 dollars) per day from pedestrians and tourists performing various acts on the tightrope near the city's iconic landmark Gateway of India. (Photo by Indranil Mukherjee/AFP Photo)

Members of the Communist New Fourth Army on parade. Note how the modern equipment contrasts with the shoeless soldiers in the foreground. (Photo by Hulton Archive/Getty Images). 6th July 1946

Mexico City resident Romina Montoya takes a playful selfie wearing a protective face mask over her eyes and nose, in Playa del Carmen, Quintana Roo state, Mexico, Wednesday, January 6, 2021. Concern is spreading that the critical winter holiday tourism success could be fleeting because it came as COVID-19 infections in both Mexico and the United States were reaching new heights. (Photo by Emilio Espejel/AP Photo)

Ukrainians attend an open military training for civilians on a training range in Kiev, Ukraine, 06 February 2022. According to a survey conducted by the Kiev International Institute of Sociology (KIIS) from December 2021, 50.2 percent of Ukrainians said they would resist in case of a Russian military intervention into their city, town or village. Every third respondent to the poll said they were ready to engage in armed resistance, and 21.7 percent said they were ready to participate in civil resistance actions. (Photo by Sergey Dolzhenko/EPA/EFE/Rex Features/Shutterstock)

Gypsies gather at Appleby in Cumbria, United Kingdom on August 12, 2021, for the biggest horse fair of its kind in Europe, which lasts till Sunday. Typically the fair takes place in June, although COVID has pushed it back to August in 2021. In the region of 30,000 people are expected to attend. (Photo by Chris Strickland/Alamy Live News)

A person takes photos of Vervet monkeys that are eating in a parking lot near the Fort Lauderdale-Hollywood International Airport in Dania Beach, Florida, USA, 10 May 2022. Over 40 descendants of smallish vervets, escaped from now closed breeding facility, are living within 1,500 acres around the Fort Lauderdale-Hollywood International airport. The Dania Beach Vervet Project is an organization established in 2016 with the purpose of promote the conservation, and education about the local free ranging vervet monkeys in Dania Beach, Florida. (Photo by Cristóbal Herrera/EPA/EFE)