Astronomy: What Makes the Shadows Hot

The more they improve their techniques, the more they refine their measurements, the more problems astronomers seem to discover. But the very recognition of those problems may point the way toward prediction of the weather of the universe, toward the type of forecast that will be essential for far-voyaging astronauts.

Cool Sun. When they set up their cameras in a Douglas DC-8 jetliner and flew high over Canada during last summer's eclipse, Drs. Guglielmo Righini of Italy and Armin J. Deutsch of the U.S. counted on snapping some of the clearest pictures yet of the sun's glowing corona. But up...