Images from Hinode Could Explain Why the Sun’s Corona is So Hot.

The sun’s temperature is hottest at the corona, it’s outer atmosphere, rather than further inward, nearer to the sun itself, as might be expected. Scientists believe that this might be because Alfven waves, magnetic ripples created when atmospheric magnetic fields are jostled together, could carry energy toward the corona. However, they were not sure if Alfven waves contained enough energy to heat the corona to its temperature of millions of degrees.

Bart De Pontieu of the Lockheed Martin Solar and Astrophysics Laboratory in Palo Alto, California and his team have used an instrument on Japan’s Hinode spacecraft to observe spicules, swaying gas jets that called spicules that arise form the sun’s surface.  They say that the only things which could cause their movements are strong Alfven waves moving upwards into the corona. These waves would have to carry at least 120 watts per square meter, more than enough to maintain the heat of the corona.