A picture made available on 09 September 2015 shows traditional mud men dancers from the Asaro District of Goroka in the Eastern Highlands Province of Papua New Guinea perform for the official opening of the Pacific Islands Forum in Port Moresby, Papua New Guinea, 08 September 2015. The Pacific Islands Forum goes from 07 to 11 September and discusses the regions vulnerability to Climate Change. (Photo by Mick Tsikas/EPA)

Participants of the the goth festival “Wave Gothic Festival” walk in fancy costumes along the festival area in Leipzig, central Germany, Saturday, May 23, 2015. About 20,000 members of the scene are expected to attend one of the world's largest gothic and “dark” culture festivals until May 25, 2015. (Photo by Jens Meyer/AP Photo)

A model poses at Checkpoint Charlie, a historic place in the German capital to promote the fashion magazine “Sous” on June 12, 2012. (Photo by Maurizio Gambarini)

Su Daocheng rides his home-made mechanical horse vehicle on a street in Shiyan, Hubei province January 18, 2015. Su spent 2 months making this 1.5 metre high and 2 metre long horse, which weighed 250 kilograms with 4 legs and 2 supportive wheels, local media reported. (Photo by Reuters/Stringer)

Men stroll past roadside vendors as a painted truck makes its way through the busy street in Kabul, Afghanistan, November, 1961. (Photo by Henry S. Bradsher/AP Photo via The Atlantic)

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)

An Afghan National Army (ANA) soldier assigned to the Mobile Strike Force Kandak fires a RPG-7 rocket-propelled grenade launcher during a live-fire exercise supervised by the Marines with the Mobile Strike Force Advisor Team on Camp Shorabak, Helmand province, Afghanistan, May 20, 2013. The Marines with the Mobile Strike Force Advisor Team instructed and mentored their ANA counterparts on how to properly utilize their weapons systems. (Photo by SSgt Ezekiel R. Kitandwe/RCT 7)

“Strike Through The Mothership”. Every May for the last 3 years I have driven down to Tornado Alley to capture some amazing storms. This supercell held so much promise to drop a tornado but one small shift in the atmosphere and all that it produced was an extreme lightning show. Photo location: Broken Bow, Nebraska. (Photo and caption by Vanessa Neufeld/National Geographic Photo Contest)