Solar flare biggest ever recorded

Wednesday, April 4th 2001, 12:00 am
By: News On 6

Before fading beyond the far side of the sun, one of the most turbulent sunspots in a decade spawned the biggest solar flare on record, scientists said.

Meanwhile, another large area of disturbance has emerged, one that could push more powerful solar salvos toward Earth.

On Monday, a sunspot called active region 9393 by scientists unleashed a major solar flare at 5:51 p.m. EDT. The flare is the biggest on record, according to researchers with the Solar and Heliospheric Observatory, one of a fleet of spacecraft monitoring solar activity and its effects on the Earth.

The blast was even larger than a 1989 solar flare that led to the collapse of a major power grid in Canada. Radiation from the new flare was so intense it saturated the X-ray detectors on two spacecraft used by the U.S. government to determine the strength of the solar blasts.

Monday's flare also was the most powerful recorded since regular X-ray data became available in 1976. But it did not head directly toward Earth, sparing sensitive electrical and communications systems, space scientists said.

Sunspot 9393 should drift out of view within a day as the sun rotates. But active region 9415, another large sunspot emerging on the visible side of the sun, could hurl destructive solar storms our way. The new spot already produced a powerful type of solar burst on Monday.

The sun, at the peak of an 11-cycle of activity, has become increasingly active in recent weeks. At such times the star is often rife with sunspots, relatively cool and dark regions on the surface caused by a concentration of temporarily distorted magnetic fields.

Sunspots spawn tremendous eruptions into the atmosphere, known as coronal mass ejections (CMEs), which hurl billions of tons of electrified gas and radiation into space.

Directed toward Earth, such storms can disrupt satellite communications and power grids and produce dramatic aurora displays in the northern and southern latitudes.

Several such outbursts over the past week prompted some of the best aurora displays in years, dazzling nighttime sky watchers as far south as Mexico.

A pair of CMEs that erupted earlier this week reached Earth on Wednesday. But the blow was glancing and hardly stirred up the magnetosphere, said SOHO project scientist Paal Brekke.

Sky watchers should be alert for auroras after nightfall. Almost certainly, the geomagnetic storm will be less intense than the one last weekend, scientists said.