Sydney Truba, 11, of Melvindale, Michigan lies in a giant lake of mud during Wayne County's 2011 Mud Day event at Nankin Mills Park July 12, 2011 in Westland, Michigan. The annual event consists of 20,000 gallons of water mixed with 200 tons of topsoil. (Photo by Bill Pugliano/Getty Images)

A plume of smoke rises above Gaza City as Israeli air strikes hit on August 18, 2011 in Gaza City, Gaza. The airstrikes came hours after attacks by militants killing Israelis in a cross border operation near Eilat, Southern Israel. (Photo by Christopher Furlong/Getty Images)

Protestors affiliated with the Occupy Wall Street movement block the entrance to the Iowa Democratic Party headquarters during a protest on December 29, 2011 in Des Moines, Iowa. Thirteen people were arrested during the protest. (Photo by Andrew Burton/Getty Images)

North Korean children wave to people on a Chinese tourist boat on the banks of Yalu River near the Chongsong county of North Korea, opposite the Chinese border city of Dandong, May 8, 2011. (Photo by Jacky Chen/Reuters)

Backdropped by a night time view of the Earth and the starry sky, the Space Shuttle Endeavour is seen docked to the International Space Station on May 28, 2011. (Photo by Reuters/NASA)

A Brussels Airlines aircraft prepares for landing in Cointrin airport during sunrise over the Mont Blanc in Geneva December 1, 2011. (Photo by Denis Balibouse/Reuters)

“Rivers Forgotten” is a journey through the passages and portals of the underground waterways that lie unseen below cities. Self-taught photographer Jeremy Kai brings these forgotten landscapes to light. Photo: Beneath the Toronto area, 2011. (Photo by Jeremy Kai)

Afghan police officers secure a transportation headquarters that was besieged for two days last weekend, on May 14, 2011 in Kandahar, Afghanistan. Taliban gunmen and suicide bombers unleashed a major assault May 7, 2011 on locations in Kandahar that included the governor's compound, the mayor's office, police stations, and an intelligence agency headquarters. (Photo by Majid Saeedi/Getty Images)