Egyptians shout anti-police slogans and hold up posters of 28-year-old Khaled Said during a demonstration in Alexandria, Egypt, Sept. 25, 2010. Tarek Fawzy/AP hide caption

Jan. 30: A man in Cairo's Tahrir Square holds an anti-U.S. sign. Peter Macdiarmid/Getty Images hide caption

Mummy Issues: Exhibition designers at the Penn Museum had to scramble to come up with a solution when bureaucratic issues botched a planned opening. The temporary fix? Papier-mache stand-ins for some of the world's most famous mummies. Penn Museum hide caption

The Tennessee coneflower is listed under the U.S. Endangered Species Act. A hybrid version of the plant, a cross between the Tennessee coneflower and the purple coneflower, was created in 2003. But experts warn that the new plant could pose a significant risk if it encroaches on the historical range of the Tennessee coneflower. J.S. Peterson/USDA hide caption

Ayman al-Zawahiri stands behind bars in an Egyptian court in 1982 during his trial as one of the alleged masterminds of the assassination of Egyptian President Anwar Sadat. Getty Images hide caption

Shiite Muslim pilgrims affiliated with Hezbollah take part in rituals last month in Baalbek, Lebanon. /AFP/Getty Images hide caption

Major droughts in 2005 and 2010 cut into the Amazon's ability to absorb carbon dioxide from the atmosphere. Drought reduces carbon-absorbing tree growth, and opens the door to more forest fires, which release carbon into the air. Seen here, a Peruvian section of Amazonia. John W. Poole/NPR hide caption

Nickelsville houses about 100 of Seattle's more than 8,000 homeless. There's a room for people with pets, several sleeping areas, and a big kitchen. Courtesy Pamela Kliment hide caption