A model wears a floral head dress as she promotes a chain of garden centres at the Royal Horticultural Soceity's Chelsea Flower Show in London, Britain, May 18, 2015. (Photo by Toby Melville/Reuters)

Drummers perform during rehearsals at the Bird's Nest National Stadium ahead of the IAAF Athletics World Championships in Beijing on August 20, 2015. The Athletics World Championships will be held at the stadium from August 22 to 30. (Photo by Greg Baker/AFP Photo)

A donkey savors warming temperatures after a long winter at the zoo in Warsaw, Poland, on Wednesday, April 8, 2015. (Photo by Czarek Sokolowski/AP Photo)

A 22-year-old woman in a wedding gown is grabbed by Guo Zhongfan, a local community officer, as she attempts to kill herself by jumping out of a seven-storey residential building in Changchun, Jilin province. According to local media, the woman tried to commit suicide after her boyfriend of four years broke up with her, just as they were making plans to get married. The woman did not sustain any injuries during the incident. (Photo by China Daily/Reuters)

“NASA's Mars rover Opportunity just celebrated its ninth anniversary on Mars – a mission that was originally meant to last just 90 days...” – The Atlantic. Photo: NASA's rover Opportunity visits Victoria Crater, viewed from orbit by the High Resolution Imaging Science Experiment on NASA's Mars Reconnaissance Orbiter in october of 2006. Opportunity is a small dot on the crater's lip, at top right. Opportunity first reached the crater's rim on September 27, 2006. (Photo by NASA/JPL-Caltech/University of Arizona via The Atlantic)

A model walks off stage in the backstage area during Frankie's Bikinis show at Mercedes Benz Swim Fashion Week in Miami, July 18, 2014. (Photo by Carlo Allegri/Reuters)

A cadet lies on the grass after collapsing during a promotion ceremony at a police school in Bogota December 7, 2012. (Photo by John Vizcaino/Reuters)

Humanoid robot bartender “Carl” interacts with guests at the Robots Bar and Lounge in the eastern German town of Ilmenau, July 26, 2013. “Carl”, developed and built by mechatronics engineer Ben Schaefer who runs a company for humanoid robots, prepares spirits for the mixing of cocktails and is able to interact with customers in small conversations. (Photo by Fabrizio Bensch/Reuters)