Dhruva Aliman does a back somersault as he dismounts from a slackline on the beach at Santa Monica, California on October 19, 2014. Slackline is a balance sport where a line of webbing is adjusted at different levels of tension between two anchor points and participants (called slackers) perform tricks and stunts including somersaults. (Photo by Mark Ralston/AFP Photo)

American soldiers with the 173rd Airborne Brigade Battle Company, on a battalion-wide mission in the Korengal Valley, looking for caves, weapons caches and known Taliban leaders, 2007. Tanner Stichter tends to Spc. Carl Vandeberge in the bushes moments after Vandeberge was shot in the stomach during a Taliban ambush, which killed one soldier and wounded two others. (Photo by Lynsey Addario)

Graduates jump as they pose for photographs in front of the Tiananmen Gate and the giant portrait of late Chinese Chairman Mao Zedong, on the Tiananmen Square in Beijing, June 19, 2014. (Photo by Reuters/Stringer)

“The Independence day”. While on storm chasing expeditions in the Tornado Alley in USA I have encountered many photogenic supercell storms. This photograph was taken while we were approaching the storm near Julesburg, Colorado on My 28th, 2013. The storm was tornado warned for more than one hour, but stayed an LP storm through all its cycles and never produced a tornado, just occasional brief funnels, large hail and some rain. Photo location: Julesburg, Colorado, USA. (Photo and caption by Marko Korošec/National Geographic Photo Contest)

A woman poses for a photograph in front of a 3D painting at HK 3D Museum in Hong Kong June 26, 2014. (Photo by Tyrone Siu/Reuters)

A “Free Syrian Army” fighter in the Bustan Pasha neighborhood of Aleppo, Syria, August 21, 2013. (Photo by James Lawler Duggan)

Francisco Javier Moreno (L), 35, and his wife Maria Auxiliadora Canca, 34, dressed as bandits pose for a photo with their horse as they participate in the third edition of “Ronda Romantica” (Romantic Ronda) in Ronda, southern Spain, May 16, 2015. Ronda Romantica is a cultural, historical and tourist event during the three days where thousands of people of Ronda and about fifty towns around of “Serrania de Ronda” (Ronda Mountain Ranges), dressed in traditional costumes, recreate the era of the bandits, drovers and romantic travelers in the nineteenth century. (Photo by Jon Nazca/Reuters)

A Tenggerese shaman praying for worshippers at Widodaren cave during the Tenggerese Hindu Yadnya Kasada festival on July 31, 2015 in Probolinggo, East Java, Indonesia. The festival is the main festival of the Tenggerese people and lasts about a month. On the fourteenth day, the Tenggerese make the journey to Mount Bromo to make offerings of rice, fruits, vegetables, flowers and livestock to the mountain gods by throwing them into the volcano's caldera. The origin of the festival lies in the 15th century when a princess named Roro Anteng started the principality of Tengger with her husband Joko Seger, and the childless couple asked the mountain Gods for help in bearing children. The legend says the Gods granted them 24 children but on the provision that the 25th must be tossed into the volcano in sacrifice. The 25th child, Kesuma, was finally sacrificed in this way after initial refusal, and the tradition of throwing sacrifices into the caldera to appease the mountain Gods continues today. (Photo by Ulet Ifansasti/Getty Images)