Three-month old cheetah cubs make their public debut at the Smithsonian National Zoo on July 24, 2012 in Washington, DC. (Photo by T.J. Kirkpatrick)

A broken picture frame is left in the tsunami-hit Arahama area, three months and two days after the magnitude 9.0 earthquake and subsequent tsunami on June 13, 2011 in Sendai, Miyagi, Japan. Japanese government has been struggling to deal with the earthquake and tsunami as well as the troubled Fukushima Daiichi Nuclear Power Plant. The fear on outbreak of virus infectious disease are mounting due to the humid rainy season on the corner and delay of the clearing the debris. (Photo by Kiyoshi Ota/Getty Images)

Northern Lynx kittens, explore their enclosure at the Highland Wildlife park on October 9, 2012 in Kingussie, Scotland. The feline twins are believed to be the type of lynx found historically in Scotland. The Highland Wildlife Park specialises in Scottish animal species, both past and present, and species that are well adapted to cold weather. (Photo by Jeff J. Mitchell)

Christopher Tubbs embraces his wife Sarah after arriving home during the homecoming of the USS Enterprise at the Norfolk Naval Station July 15, 2011 in Norfolk, Virginia. In its 184 days away from Norfolk, the USS Enterprise cruised nearly 60,000 miles while supporting operations in Afghanistan and Iraq. (Photo by Win McNamee/Getty Images)

Dancers from the British theater company Motionhouse perform a show with excavators entitled “Traction” on the Prado beach in Marseille, France, on May 10, 2013. (Photo by Boris Horvat/AFP Photo)

A young Thai man jumps in the air and cheers as his rocket takes off at the Bun Bang Fai Rocket Festival on May 10, 2015 in Yasothon, Thailand. (Photo by Taylor Weidman/Getty Images)

“Freedom”. After the 30 years banning import large motorcycle, in 2007, the Taiwan government reopened the import licensing of the motorcycle displacement over 550 cubic centimeter. Those large bikes, which were never seen before, were strange thought and treated unequally frequently. However, those adversity will not stop those enthusiastic bike riders from chasing the road of freedom. Photo location: Taiwan. (Photo and caption by 火花 羅/National Geographic Photo Contest)

Actresses Zelda Williams and Kelly Monaco attend Nintendo's celebration of the launch of Super Mario 3D Land at Siren Studios on November 3, 2011 in Hollywood, California. (Photo by Jason Merritt/Getty Images for Nintendo)