Coronal loops, seen here, are fountains of multimillion-degree gas in the atmosphere of the sun. They are often precursors to solar flares, which emit strong bursts of electromagnetic energy. NASA/AP hide caption

itoggle caption NASA/AP

Four-year-old Tai Shan, aka "Butterstick," is traveling from Washington, D.C., to China on Thursday as part of an agreement between the National Zoo and the China Wildlife Conservation Association. The panda will be bred in an effort to reintroduce the species into the wild. Mehgan Murphy/National Zoo hide caption

itoggle caption Mehgan Murphy/National Zoo

The space shuttle Discovery orbits in space in a March, 2009 mission. The nearly 30-year-old space shuttle program is set to end in 2010. After five more missions, NASA's three shuttles — the Discovery, Atlantis and Endeavour – will be retired. Courtesy NASA hide caption

itoggle caption Courtesy NASA

Alexander Kendrick stands in the Lake of the Clouds after testing his invention. He and the team of cavers executed the deepest known digital communication ever to take place in the United States. Brad Horn for NPR hide caption

itoggle caption Brad Horn for NPR

The bdelloid rotifer Philodina gregaria. Bdelloid rotifers are tiny invertebrates that reproduce asexually. Courtesy of Micrographia hide caption

itoggle caption Courtesy of Micrographia

Water in the atmosphere traps heat, like glass in a greenhouse. When there's less water vapor in the atmosphere, less heat is trapped. Space Frontiers/Getty Images hide caption

itoggle caption Space Frontiers/Getty Images

An artist's rendition of two Sinosauropteryx dinosaurs, showing their short, bristle-like feathers along the midline of the head, neck, back and around the tail, forming irregular stripes. Chuang Zhao and Lida Xing hide caption

itoggle caption Chuang Zhao and Lida Xing