People take part in the Classic Ride Rally in downtown Valencia, eastern Spain, 23 November 2014. Some hundred people on classic bikes from the 20's to the 70's participated in the rally. (Photo by Kai Foersterling/EPA)

Spectators cheer as the United Launch Alliance Delta 4-Heavy rocket, with NASA's Orion spacecraft mounted atop, lifts off from the Air Force Station, December 5, 2014, in Cape Canaveral, Fla. (Photo by Smiley N. Pool/AP Photo/Houston Chronicle)

Zhao Qiang walks across a street in Shenyang, Liaoning province, April 14, 2014. Zhao, a community officer of the China Disabled Persons' Federation, was diagnosed with multiple when he was two, with the resulting tumour affecting the growth of his left leg, his grandmother told local media, citing a doctor's diagnosis. His uncle modified his shoes, fitting them with stools, to allow Zhao to stand and walk. (Photo by Reuters/Stringer)

Walkers cross the river Waalbrug during the first day of the 98th annual four-days walking event, the “Vierdaagse” in Nijmegen, Netherlands, July 15, 2014. The “Nijmeegse Vierdaagse” is an annual public four-day field march which is held since 1909 in the third week of July. (Photo by Erik van 't Wout/EPA)

These stunning images could be mistaken for a cheetah ravenously chasing down a dog, but in fact, the pair are best of friends. Savanah, the one-and-a-half-year-old cheetah and Max, who is just a few weeks younger, were put together when Savanah was just 10-weeks-old. Ever since, their friendship has amazed visitors at Cincinatti Zoo, who are delighted but confused as to why the spotted beast hasnt eaten the dashing hound. So, when it snowed, Savanah and Max just like young children were very excitable and wasted no time playing in the snow. (Photo by Caters News Agency)

Some of London's telephone operators and engineers, trying out their gas masks at the anti-gas civilian training centre in Gloucester, where they were taught how to deal with gas attacks. (Photo by Harry Todd/Fox Photos/Getty Images). 13th February 1937

In this undated photo made available by journal Nature on January 15, 2014, a northern bald ibis (Geronticus eremita) flies in Tuscany, Italy. A new study released Wednesday, January 15, 2014 says the birds choreograph the flapping of their wings, getting a boost from an updraft of air in the wake of the flapping wings by flying behind the first bird and off to the side. When a flock of birds take advantage of these aerodynamics, they form a V. (Photo by Markus Unsöld/AP Photo)

A visitor holds an Israeli-made rifle during the 8th International Land and Naval Defense system exhibition, in New Delhi, India, on February 6, 2014. (Photo by Anindito Mukherjee/Reuters)