An elephant “kisses” a visitor during a show at an elephant training school in Xishuangbanna, Yunnan province, April 18, 2015. Some 16 elephants live at the school and give four 30-minute performances everyday for visitors. (Photo by Wong Campion/Reuters)

An artist shows her hands after working on a wall as part of a campaign to call for coexistence and the renouncement of violence through the painting of walls in Sanaa, Yemen March 15, 2015. (Photo by Mohamed al-Sayaghi/Reuters)

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)

Athletes from Australia's Olympic team going to the 2016 Olympics in Rio present their uniforms alongside Brazilian Samba dancer Sashya Jay at an official unveiling ceremony at Sydney's Bondi Beach, March 30, 2016. (Photo by Jason Reed/Reuters)

“The Mikoyan MiG-31 (NATO reporting name: Foxhound) is a supersonic interceptor aircraft developed to replace the MiG-25 “Foxbat”. The MiG-31 was designed by the Mikoyan design bureau based on the MiG-25”. – Wikipedia

Photos: The Mikoyan MiG-31 “Foxhound”. Russia, April 2012. (Photo by Alexandr Pak; Source: LiveJournal)

“Horst Faas (28 April 1933 – 10 May 2012) was a German photo-journalist and two-time Pulitzer Prize winner. He is best-known for his images of the Vietnam War”. – Wikipedia

Photo: A U.S. crewman runs from a crashed CH-21 Shawnee troop helicopter near the village of Ca Mau in the southern tip of South Vietnam, December 11, 1962. Two helicopters crashed without serious injuries during a government raid on the Viet Cong-infiltrated area. Both helicopters were destroyed to keep them out of enemy hands. (Photo by AP Photo/Horst Faas)