Scientists Soon to Forecast Solar Storms

SAN FRANCISCO —  As the sun reaches the peak of its 11-year cycle of activity this year, scientists say they are closer to understanding the process and more able to predict accurately the severity of solar storms.

Space weather forecasts are becoming important as more people and satellites are launched into space, and the world increasingly depends on sensitive electronics that can be fried by particles and radiation emitted by the sun.

Though researchers for years have noticed that solar activity increases every 11 years or so, they have been unable to accurately predict the severity of the eruptions. The current cycle is expected to peak sometime in 2000.

“One funny thing about predicting solar activity is some people actually expect you to get it right,” said David Hathaway, a researcher at NASA’s Marshall Space Flight Center. “We’ve had a checkered past in . . . making predictions.”

For nearly 150 years, scientists have observed that the dark blemishes on the solar surface known as sunspots pop up with much more frequency every 11 years. More recently, the spots have been associated with increased sun eruptions.

Sunspots and solar activity are the result of the star’s magnetic field lines twisting and tangling as the sun rotates. Unlike the solid Earth, the gas that makes up the sun rotates at different speeds at different latitudes.

The sun magnetically unwinds by spewing millions of tons of particles and gases into space, producing a solar storm, according to the most accepted theory.

Hathaway presented a study Dec. 16 at the fall meeting of the American Geophysical Union examining several methods of prediction and compared their forecasts of previous cycles. Three forecast techniques proved reliable, he said.

All three used Earth’s magnetic fluctuations to predict as much as six or seven years in advance the intensity of the solar cycle. Previously, the most reliable estimates could be made only after the period of high activity began.

“There’s something that’s happening on the sun about the time of the solar minimum that is telling us ahead of time what the next cycle is going to be like,” Hathaway said.

It appears the activity in 2000 will be slightly more intense than average, he said.

Earth is protected from the radiation, particles and gases by its atmosphere and its own magnetism.