Solar Wind Born of Colliding Magnetic Fields

April 2, 2008 -- The solar wind paints Earth's skies with auroras and pushes solar sails through space, but just how the streams of electrically charged particles flow out of the sun has been a mystery until now.

"It has been debated for many years," said Louise Harra, a University College London researcher who on Wednesday unveiled the sun's secret.

Like most phenomena associated with stars, the process is violent. An international team of scientists discovered that pockets of hot gases on the sun's surface, which pool around bright knots of magnetic activity, spurt out into space when the sun's snarling, snaking magnetic fields collide.

At the Royal Astronomical Society meeting, Harra planned to show images from the orbiting Hinode spacecraft showing magnetic fields linking two bright spots on the sun that were nearly 500,000 kilometers, or 311,000 miles, apart -- a distance equivalent to 40 Earths placed side by side.

When the magnetic fields smashed into each other, charged gases flew out in all directions, forming the solar wind.

"It is fantastic to finally be able to pinpoint the source," Harra said, adding that the next step is to figure out how the wind is transported through the solar system.