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)

Joanne Froggatt poses with her award for Best Supporting Actress in a Series, Mini-Series or TV Movie for her role in “Downton Abbey” backstage at the 72nd Golden Globe Awards in Beverly Hills, California January 11, 2015. (Photo by Mike Blake/Reuters)

American socialite Kylie Jenner shows off her summer bikini style with friends in the second decade of June 2024. (Photo by kyliejenner/Instagram)

Barbadian singer Rihanna looked incredible as she stripped down to the lacy underwear set for Fenty brand in the last decade of September 2024. (Photo by Savagexfenty)

Skeleton involves a person riding a small sled down a frozen track while lying face down. The sport is a more intense form of luge because skeleton competitors leap onto the sled and slide downhill head first. Skeleton athletes can reach up to 80 mph on straightaways, causing forces up to 5g, so the helmet is a critical component for attitude as well as safety.

Soo Joo Park poses during a photocall before the Chanel Spring/Summer 2019 women's ready-to-wear collection show during Paris Fashion Week in Paris, France, October 2, 2018. (Photo by Gonzalo Fuentes/Reuters)

Chloe Ferry attends the Geordie Shore series 15 “Shag Pad on Tour” cast launch at Tower Bridge on August 16, 2017 in London, England. (Photo by Karwai Tang/WireImage)

A Hindu devotee is helped by other people as she walks on burning coals during a religious procession Vel Festival of the Hindu goddess Maha Mariamman (Sheetla Mata), in New Delhi, India, 06 April 2017. People get their bodies pierced with different kinds of metal needles and rods and participate in a religious procession as thanks giving gesture to the goddess in return of their fulfilled wishes during the annual procession. (Photo by Rajat Gupta/EPA)