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

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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

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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

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An ash plume rises from the Icelandic volcano Eyjafjallajokull on April 14, 2010. Arni Saeberg hide caption

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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

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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

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

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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

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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

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