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Solar scientists: 'S' marks the violent spots

'S' marks the spot of a coronal mass ejection on the sun

CNN's Marsha Walton reports on how predicting solar storms can help electric companies and satellite operators
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March 9, 1999
Web posted at: 3:59 p.m. EST (2059 GMT)

WASHINGTON (CNN) -- Scientists on Tuesday announced a possible new method to forecast the most turbulent solar storms in advance, based on a unique "S"-shaped feature on the surface on the sun.

The explosions, as powerful as billions of nuclear explosions, can disrupt radio communications and electrical power systems on the Earth and satellites orbiting above.

Using pictures from the Japanese satellite Yohkoh, researchers frequently detected the tightly coiled energy patterns just before a solar storm erupted.

"'S' marks the spot," said Dr. Alphonse Sterling of Computational Physics Inc., of Fairfax, Virginia, in a statement. "We have found a strong correlation between an S-shaped pattern on the sun, called a sigmoid, and the likelihood that an ejection will occur from that region within days. Each sigmoid is like a loaded gun that we now know has a high probability of going off."

The S-shaped sigmoids were found in the sun's southern hemisphere. The tightly coiled energy frameworks seemed reversed like the number "2" in the northern half.

Researchers believe the signature "S" shape is caused by twisted magnetic fields on the surface of the sun. Solar storms, also known as coronal mass ejections, are huge clouds of charged particles that periodically explode from the sun. The eruptions spew as much as 10 billion tons of electrically charged gas out into the solar system at speeds up to 1 to 2 million miles per hour.

Typically, a solar storm takes about four days to travel the 93 million miles from the sun to the Earth.

The clouds of charged gas that make up the storm can damage sensitive microelectronics aboard satellites and also overload electrical power grid on the Earth. In 1989 a solar storm caused a blackout in eastern Canada. Many scientists predict similar electrical turbulence next year, as such sun storms seem to occur in 11-year cycles.

Should the high-energy particles "flow gangbusters" through an unprepared power system, it could wind up with "fried green transformers," quipped physics professor Dr. Richard Canfield from Montana State University in Bozeman, Montana.

More benignly, solar storms can stimulate heightened activity of the Northern and Southern Lights when the cloud of charged particles comes into contact with the Earth's own magnetic field.

In recent years, scientists have used solar telescopes like the Solar and Heliospheric Observatory to monitor the sun for storms. Such instruments can detect them as they occur.

In the future, using indicators like the "S"-shaped sigmoid feature, solar scientists could predict accurately the coronal disruptions before they occur.

"This discovery of a way to possibly provide early warning of approaching solar storms could prove useful to power companies, the communications industry and organizations that operate spacecraft, including NASA," George Witbrowe of NASA said in a statement. "This is a major step forward in our understanding of these tremendous storms."

New images reveal 'honeycomb' source of solar wind
February 4, 1999
Sun-like stars said to emit superflares
January 8, 1999

Yohkoh Public Outreach
Computational Physics Inc.
Montana State University - Bozeman
SOHO: The Solar and Heliospheric Observatory
SOHO Explore !!!
   •Live from the Sun
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