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)

Jennifer Oeser of Germany competes in the Women's Heptathlon Long Jump on Day 8 of the Rio 2016 Olympic Games at the Olympic Stadium on August 13, 2016 in Rio de Janeiro, Brazil. (Photo by Alexander Hassenstein/Getty Images)

Miss Universe contestants Laurien Angelista, of Curacao, left, Yasmin Verheijen, of the Netherlands, and Kaci Fennell, of Jamaica, walk in the pool during the Yamamay swimsuit runway show, Wednesday, January 14, 2015, in Doral, Fla. The Miss Universe pageant will be held January 25 in Miami. (Photo by Lynne Sladky/AP Photo)

Injured horses huddle together in Oklahoma City on Monday. (Photo by Chris Landsberger/The Oklahoman)

A tourist poses for a picture with the Sphinx at the Pyramids of Giza in Cairo, Egypt, on October 19, 2011. (Reuters/Jamal Saidi)

Participants dressed as Santa Claus take part in the Great Edinburgh Santa Run on December 11, 2011 in Edinburgh, Scotland. Around a thousand people took part in the annual fundraising event, with all money raised being donated to the charity “When You Wish Upon a Star”. (Photo by Jeff J. Mitchell/Getty Images)

Horizontal lightning was captured in this picture taken over an hour in Ensenada, Mexico on October 28, 2021. (Photo by Edgar Lima/Animal News Agency)

A model walks the runway at the annual Victoria's Secret fashion show at Earls Court on December 2, 2014 in London, England. (Photo by Tim P. Whitby/Getty Images)