Residents survey the destruction after a tornado hit Pratt City, Ala., on April 27. Short-term forecasting of twisters like the ones that swept the South this week has grown increasingly accurate, but long-term forecasting remains highly unreliable. Butch Dill/AP hide caption

itoggle caption Butch Dill/AP

The Alpha Magnetic Spectrometer is loaded into the vehicle that would take it to the space shuttle launchpad on March 15. The $2 billion cosmic ray detector will be carried to the International Space Station on Endeavour's final flight. NASA hide caption

itoggle caption NASA

The brown marmorated stink bug has inundated the mid-Atlantic, taking its toll on crops across the region. Researchers are investigating whether a type of parasitic wasp can bring down stink bug numbers. Jeff Wildonger/USDA Beneficial Insect Research Lab hide caption

itoggle caption Jeff Wildonger/USDA Beneficial Insect Research Lab

Researchers say that humpback whales are able to swim in remarkably straight lines during their seasonal migrations. They don't yet know, though, how the whales do it. Kike Calvo/AP hide caption

itoggle caption Kike Calvo/AP

Phil Radford, executive director of Greenpeace USA, inspects oil-covered reeds while visiting the disaster site on May 20, 2010 south of Venice, Louisiana. A year after the spill, BP has yet to distribute $450 million dollars to scientists studying the disaster. John Moore/Getty Images hide caption

itoggle caption John Moore/Getty Images

The placenta, the nutrient-rich organ shown in this model as the layer above the baby's feet, makes its own serotonin. Mark Evans/iStockphoto.com hide caption

itoggle caption Mark Evans/iStockphoto.com

A scientist stands in front of an ice-rich permafrost exposure in the coastal zone of Herschel Island, Yukon Territory, Canada. Ice in the permafrost is melting, contributing to rapid erosion. Michael Fritz/Alfred Wegener Institute hide caption

itoggle caption Michael Fritz/Alfred Wegener Institute

Researchers at the Centers for Disease Control and Prevention are working on a new all-natural insect repellent. It not only keeps bugs away — it kills them in seconds. Trebol-a/Flickr hide caption

itoggle caption Trebol-a/Flickr