Sean Morey, then with the Arizona Cardinals, celebrates after blocking a punt against the Seattle Seahawks in 2007. Morey, who suffers from post-concussion syndrome, retired from the NFL in 2010 on the advice of doctors. Stephen Dunn/Getty Images hide caption
Janet Yellen smiles as President Obama announces her nomination for Federal Reserve chairwoman on Oct. 9. Jewel Samad/AFP/Getty Images hide caption
Cannonball jellyfish soak up the sun on a South Carolina beach. Fishermen are now pursuing the pest that used to clog their shrimping nets. Courtesy of Steven Giese hide caption
New Jersey Gov. Chris Christie listens during a Jan. 9 news conference in which he denied any knowledge of lane closings on the George Washington Bridge when they occurred in September. Mel Evans/AP hide caption
Linda Door protested outside the U.S. Supreme Court as it began hearing arguments on the constitutionality of the Affordable Care Act in March 2012. Carolyn Kaster/AP hide caption
Speaker of the House John Boehner (right) speaks during the leadership press conference at the House Republican Issues Conference in Cambridge, Md., on Thursday. Friday's press conference, on the last day of the retreat, was canceled. JIm Watson/AFP/Getty Images hide caption
Performers get ready before the start of a Chinese New Year parade in Hong Kong on Jan. 31. Philippe Lopez/AFP/Getty Images hide caption
Gund Kwok troupe member Heang Ly takes a break next to her lion costume during a rehearsal in Boston's Chinatown. Hansi Lo Wang/NPR hide caption
A protest of the Keystone XL pipeline last March along its proposed route near Bradshaw, Nebraska. NH/AP hide caption
Pipefitters work on construction of the Keystone XL Pipeline's southern portion outside Tulsa, Okla., last January. PR Newswire hide caption
Andrew Ng and Daphne Koller, Stanford University computer science professors who started Coursera, pose for a photo at the Coursera office in Mountain View, Calif., on Aug. 2, 2012. Jeff Chiu/AP hide caption
Dark blue: It's going to take a foot or more of snow to close schools. Green: Any snow's going to shut things down. reddit.com/user/atrubetskoy hide caption
Years ago, the boulder in the foreground broke loose and rolled on to this farm in northern Italy. Then this month, the boulder in the center of the photo tumbled down the mountain, tore through a barn and came to rest in a field. Fortunately, no one was hurt. Markus Hell/Tareom.com/AP hide caption
Skydivers using hand signals to coordinate a rescue of James Lee, who is unconscious. The Telegraph hide caption