Elinor Ostrom in January 2011. Raveendran /AFP/Getty Images hide caption

itoggle caption Raveendran /AFP/Getty Images

Left to right: Nobel Peace Prize laureates President Ellen Johnson Sirleaf of Liberia, Liberian "peace warrior" Leymah Gbowee and Tawakkul Karman of Yemen.

AP hide caption

itoggle caption AP

Remnants of Tycho's Supernova, seen in an X-ray/infrared composite image. The supernova was observed by Tycho Brahe and other skywatchers in 1572.

MPIA/NASA hide caption

itoggle caption MPIA/NASA