Tiny 'nanoflares' might heat the Sun's corona

Why is the Sun's million-degree corona, or outermost atmosphere, so much hotter than the Sun's surface? This question has baffled astronomers for decades. Today, a team led by Paola Testa of the Harvard-Smithsonian Center for Astrophysics (CfA) is presenting new clues to the mystery of coronal heating using observations from the recently launched Interface Region Imaging Spectrograph (IRIS). The team finds that miniature solar flares called "nanoflares" -- and the speedy electrons they produce -...