Evidence Links Sunspots to Curved Magnetic Fields : SCIENCE FILE / An exploration of issues and trends affecting science, medicine and the environment

Scientists from NASA’s Goddard Space Flight Center reported in Nature that they have found direct evidence for the theory that sunspots--mysterious dark patches on the sun’s surface--are caused by curved magnetic fields that stick out from the sun like croquet wickets. The number of sunspots rises and falls in an 11-year cycle of solar activity that can disrupt radio communications on Earth and might also affect Earth’s climate.

The horseshoe-shaped magnetic fields are created deep in the sun, and then reach up to poke through the surface, clustering there like a bunch of croquet hoops. The theory says hot solar gas flows toward the hoops and then plunges toward the center of the sun. As the gas dives into the sun, it draws off heat, producing a relatively cool spot at the surface. The NASA team said they had detected gas diving under sunspots, confirming the theory.