This article is provided as a public service by the Geophysical Institute, University of Alaska Fairbanks, in cooperation with the UAF research community. Carla Helfferich is a science writer at the Institute. Common sense and general experience teach that the farther something is from a heat source, the cooler it is. When it comes to the sun, though, common sense fails. The solar corona, a halo of incandescent gases that stream out into space for distances several times the sun's diameter, is hotter than the sun's surface.
Nobody is quite sure why the corona seems to violate the basic rules of thermodynamics.
It's a question of more than abstract interest, too. Figuring out how the corona works is of special interest to Alaskans, because upheavals in the corona are responsible for some of our favorite phenomena, such as the aurora. They also produce some of our troubles, such as failures in radio and satellite communications, some power outages, and even corrosion in the Trans-Alaska Pipeline. The solar wind, which triggers these blessings and banes, is an extension of the solar corona. The issue of Science for February 11 of this year reported on some recent debates about the hot corona.