Eruption on sun triggers radio blackouts; light show possible

WASHINGTON - A strong solar flare early Wednesday morning caused some radio blackouts on parts of the Earth facing the sun and more are possible as the active solar region rotates toward the center of the sun, NASA announced.

The space agency said on its science web site that the Solar and Heliographic Observatory (SOHO) satellite recorded a massive solar flare, called an X-class flare, about 6:37 a.m. EDT Wednesday.

Streams of electromagnetic energy erupting from the flare disrupted some radio communications, the announcement said.

SOHO, a joint project of NASA and the European Space Agency, also detected two coronal mass ejections, huge clouds of electrified gas, erupting from the sun on Monday and Tuesday.

The National Oceanographic and Atmospheric Administration, which predicts the effects of solar eruptions, said there was a 40 percent chance that the mass ejection would trigger a disruption of the Earth's magnetic field by Friday. This could create aurora lights reaching into the mid-lattitudes, which would include the southern U.S. Aurora lights are common in the far northern and southern latitudes.

The coronal mass ejection sent a bubble of plasma, or electrified gas, toward the Earth at more than 2 million miles an hour. The first shock wave of the fast-moving mass was expected to smash into the Earth's magnetosphere, the magnetic field that surrounds the planet, on Thursday. Material from a second, more powerful ejection is expected on Friday.

The aurora, or northern and southern lights, are a shimmering glow in the sky caused when energetic particles from the sun strike atoms of gas in the upper atmosphere of the Earth. The Earth's magnetic field protects the planet from these solar particles, but the field dips low over the poles. For this reason, the aurora is most commonly seen at high northern and southern latitudes. Unusually powerful solar bursts can produce the blue and green lights in the night sky closer to the equator.

Experts say that the aurora is best viewed around midnight, local time.

The corona mass ejection poses no health risk to people on the ground, but such solar bursts have been known to damage spacecraft and to disrupt electrical power grids. Most utility systems and satellites now are designed to resist such effects, however.

The sun is currently at the peak of its 11-year cycle of intense activity.

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On the Net:

Solar and Heliospheric Observatory: http://sohowww.nascom.nasa.gov/

NOAA Space Environment Cebter: http://www.sec.noaa.gov/SWN/