FLARING SUN NOT BAD, SAY EXPERTS : SATELLITE PICTURES SHOW SHOCK WAVE.

Byline: Paul Recer Associated Press

Dramatic pictures from a new satellite show a shock wave moving across the face of the sun just after a solar flare sent an immense bubble of superheated gas toward Earth at almost 2 million miles an hour.

Just a small eruption, scientists assured Wednesday - worth noting only because it produced the first close-up photographs of a solar flare.

It's nothing-out-of-the-ordinary size isn't expected to disrupt regular radio, telephone, television or cable communications, they said.

Also, virtually no danger exists of power blackouts, added David Speich of the National Oceanic and Atmospheric Administration's space weather center in Boulder, Colo.

``The effects will be almost none,'' Speich said. Some international shortwave radio operators, he said, could experience brief moments of minor signal distortion.

Satellite operators were notified routinely, but officials said it would take a larger event to affect orbiting equipment, mostly shielded from all but the biggest solar flares.

Massive solar eruptions of the past have caused blackouts, cooked satellites and disrupted communications for hours. But by the sun's awesome standards, this week's eruption was barely a firecracker, the National Aeronautics and Space Administration said.

Scientists predict that any contact would be made by 8 a.m. EDT today, but won't be able to see anything unless it hits the planet.

``We don't see a thing because it's left the sun in a violent departure and has been traveling through space between the sun and the Earth during that time,'' Speich said.

For scientists, the excitement was that pictures taken by the space agency's SOHO satellite detected the wave moving across the sun's gaseous surface ``like a tsunami tidal wave,'' NASA's chief scientist on the SOHO satellite, Art Poland, said. ``That's the first time we have seen the shock wave.''

Poland said he and his colleagues hesitated even to announce the flare because of its ordinary size, but he said the dramatic images from the new satellite led to the space agency's release of information.

Four similar flares have occurred this year, and the most recent differs only in that its eruption was directed more toward the Earth, that scientist said. Material from a solar explosion often speeds harmlessly out into space, away from Earth.

Earth's magnetic shield protects the planet against all but the largest solar flares, Speich said.

In March 1989, fallout from a solar flare caused the largest geomagnetic storm in 30 years. It knocked out a power grid in Quebec for nine hours. Parts of the power grid in the northeastern United States also experienced brief disruptions.

No satellites were damaged by that event, Speich said, but geomagnetic storms were blamed for failure of the GOES 8 weather satellite in 1994 and of a telephone communications satellite last January.

High-energy electrons from a flare can send an electrical arc into a satellite's wiring, scrambling the computer or, rarely, damaging an electronic chip or a switch. Most satellites are designed to protect against this.

At COMSAT World Systems, which operates 24 communications satellites, engineers ordered up some protective commands.

COMSAT engineer Carl Jeffcoat said his satellites have withstood greater jolts than that threatened by the recent flare.

``At the moment, while certainly we're interested, I wouldn't say that we're concerned,'' he said.

Damaging flares are rare, more apt to happen during the active part of the sun's 11-year cycle. Within four years or so, that cycle will reach ``solar max'' and spew out scores of flares every day like the one that occurred this week, Speich said.

At solar max, he said, flares 10 times bigger than the recent event will occur four to five times a day. Once every 24 to 48 hours, a flare will occur that is 100 times bigger.

Only a few ever affect the Earth, Speich said.

By Earthly standards, any solar flare is gigantic. Billions of tons of charged hydrogen and helium, ``stuff the sun is made of,'' suddenly erupt from the surface, said Speich.

Huge blobs of the material, held together by magnetic forces, streak into space at hypersonic speeds. If the material travels toward Earth, it can slam into the planet's magnetic field after two or three days and set it to vibrating. That can transfer energy to electric wiring, pipelines and satellites.

CAPTION(S):

Photo

Photo: (Color) A telescope aboard the Solar and Heliospheric Observatory spacecraft took this photo of the sun.

Associated Press