A gallery assistant holds a print of an Andy Warhol artwork estimated to fetch 1,500 GBP in Bonhams auction house on November 25, 2011 in London, England. The auction of prints of works ranging from old masters to contemporary artists takes place in London on November 29, 2011. (Photo by Oli Scarff/Getty Images)

A gallery assistant holds a rare 14th century time-telling device device in Bonhams auction house on December 9, 2011 in London, England. The instrument, which dates from 1396 and was discovered in a shed in Queensland, Australia, is due to be auctioned on December 13, 2011 and is expected to fetch 200,000 GBP. (Photo by Oli Scarff/Getty Images)

In his series “Ballerinas of Cairo”, photographer Mohamed Taher documents Egyptian dancers making the city streets their stage – pirouetting, leaping and posing their way through their country’s sprawling capital. The photos are, at first glance, stunning snapshots of a city’s vibrant culture in motion. (Photo by Mohamed Taher/Ballerinas of Cairo)

A U.S. Army soldier with the 10th Special Forces Group and his military working dog jump off the ramp of a CH-47 Chinook helicopter from the 160th Special Operations Aviation Regiment during water training over the Gulf of Mexico as part of exercise Emerald Warrior 2011 on March 1, 2011. (Photo by Tech. Sgt. Manuel J. Martinez/U.S. Air Force)

Penny Farthing cyclists ride near Tower Bridge on June 9, 2011 in London, England. The riders have cycled from Paris ahead of the IG Markets London Nocturne cycling event on June 11, 2011. (Photo by Peter Macdiarmid/Getty Images)

Monsoon thunderstorm in Sierra Vista, Arizona. 9 Sept, 2011. (Photo by Steven Maguire)

Brad Snead walks past melting ice on the Cook Inlet beach, Saturday, March 26, 2011, in Kenai, Alaska, while looking for agates. (AP Photo/Peninsula Clarion, M. Scott Moon)