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)

This close-up image – of a Holi Festival celebrant in Vrindivan, India, coated in neon-colored powder – was submitted to National Geographic’s Your Shot in the last week of March. On April 1 we published it on our Daily News site, along with seven other bright scenes captured during the Hindu spring Festival of Colors. (Photo by Tinto Alencherry/National Geographic)

“Cassowaries are large, flightless birds related to emus and (more distantly) to ostriches, rheas, and kiwis”, writes Olivia Judson in the September issue of National Geographic magazine. How large? People-size: Adult males stand well over five foot five and top 110 pounds. Females are even taller, and can weigh more than 160 pounds. Dangerous when roused, they’re shy and peaceable when left alone. But even birds this big and tough are prey to habitat loss. The dense New Guinea and Australia rain forests where they live have dwindled. Today cassowaries might number 1,500 to 2,000. And because they help shape those same forests – by moving seeds from one place to another – “if they vanish”, Judson writes, “the structure of the forest would gradually change” too. (Photo by Christian Ziegler/National Geographic)

Nelson Hernandez flashes the victory sign as he shows off one of the voodoo dolls that he is selling at El Viejo Lazaro Botanica to try and help the Miami Heat fans root their team on against the Dallas Mavericks in the NBA finals on June 9, 2011 in Miami, Florida. The dolls made from cotton come in white or black and they are all the same size. The user of the doll must have the name of the player attached to the doll, which is filled with cotton, herbs, sticks and a special powder. (Photo by Joe Raedle/Getty Images)

SI bodypaint model, soccer player Alex Morgan (L) attends SI Swimsuit On Location hosted by Haze Nightclub at the Aria Resort & Casino at CityCenter on February 15, 2012 in Las Vegas, Nevada. (Photo by Michael Loccisano/Getty Images for Sports Illustrated)

A competitor jumps from the Old Bridge during Red Bull Cliff Diving Competition in Mostar, Bosnia and Herzegovina on August 15, 2015. (Photo by Dado Ruvic/Reuters)

David Colturi of the USA dives from the 27 metre platform during the fifth stop of the Red Bull Cliff Diving World Series in Polignano a Mare, Italy on August 28 2016. (Photo by Dean Treml/ANSA/Red Bull Press Office)

Models pose backstage ahead of the Review of Australian Fashion Week show as part of Mercedes Benz Fashion Festival Sydney 2011 at Sydney Town Hall on August 24, 2011 in Sydney, Australia. (Photo by Lisa Maree Williams/Getty Images)