Abdel Hakim Belhaj (center left), a prominent militia commander, walks with Transitional National Council Chairman Mustafa Abdel Jalil in Tripoli on Sept. 10. The battle to oust Moammar Gadhafi produced a number of leaders who will have to work together to form a new government. Francois Mori/AP hide caption

The main ring of the Tevatron, seen in a time exposure. For a quarter century, the particle accelerator at a lab outside Chicago was the most powerful machine of its kind in the world. Reidar Hahn/Fermilab hide caption

Penetrator bombs, commonly known as bunker busters, are stored on pallets at an ammunition plant in McAlester, Okla., in 2002. The U.S. sold 55 bunker busters to Israel in 2009, according to a recent Newsweek report. Sue Ogrocki/AP hide caption

Then-Sen. Barack Obama drew enthusiastic crowds at a rally in Columbus, Ohio, just days before the 2008 election. Now, after a few rocky moments with the coalition that helped send him to the White House, and with a re-election battle looming, Obama is trying to re-energize his supporters. Joe Raedle/Getty Images hide caption