This friction, called viscosity, may help explain why the corona is more than 100 times hotter than the Sun's surface, a mystery that has occupied solar researchers for decades. Just as a guitar string vibrates when plucked, coronal loops move back and forth after being disturbed by a flare. We expected progress, but few major surprises. Viscosity is a measure of the friction, or resistance to flow, in a fluid. Pudding is harder to stir than water because pudding has greater viscosity.
High viscosity is responsible for the annoyingly slow flow of ketchup and molasses.
The research will be published in the August 6 issue of Science. Dr. Valery Nakariakov, postdoctoral fellow at St. Andrews University, Scotland, is first author on the paper. The greater than expected viscosity in the corona may help resolve a solar conundrum. Solar physicists suspect that magnetic energy produced by the roiling, electrically charged gases on the solar surface is somehow transferred to the corona, heating it. We thought magnetic energy could be used to heat the corona, but our old theory of a low viscosity corona made the process so inefficient that we could not see how it was done.