SPACE.com -- Sun Shoots 10th Major Flare Tuesday, Possibly Strongest Yet

The major solar flare of Nov. 4. The flare erupted off the visible disk of the Sun, just behing the right limb. Loops of hot gas jumped into view, however, emitting X-rays and other radiation. CREDIT: SOHO/NASA/ESA

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	Sun Shoots 10th Major Flare Tuesday, Possibly Strongest Yet By Robert Roy Britt Senior Science Writer posted: 04:53 pm ET 04 November 2003

A amazing 10th major flare in two weeks leapt from the Sun Tuesday, adding one more colossal eruption to a list that has already made history

UPDATED AT 9:21 P.M. ET

Editor's Note: The latest news on this flare is here.

The 10^th major flare in two weeks leapt from the Sun Tuesday, adding one more colossal eruption to a list that has already made history. This one could be the strongest yet.

Scientists are still evaluating the power of the latest outburst, which occurred at about 2:40 p.m. ET. It has tentatively been ranked at least an X17 on a scale in which X denotes severe and the number rates just how severe. [Animations below]

Paal Brekke, deputy project scientist for the SOHO spacecraft, told SPACE.com the flare could be as strong as X20 "or much higher," which would make it the most severe recorded in the modern era of satellites.

"This one saturated the X-ray detectors on the NOAA's GOES satellites that monitor the Sun," Brekke said. "The jury is therefore out on the definitive classification of the flare."

Other scientists have indicated the flare may indeed be an X20 or stronger. Only two X20 events have ever been recorded, one in 2001 that was not Earth-directed and had little effect, and another in 1989.

Tuesday's remarkable flare emanated from Sunspot 486, a dark region of the Sun about 15 times the size of Earth. The sunspot is rotating around to the back side of the Sun, so this outburst was not pointed directly at Earth.

X-ray and light radiation from the solar eruption arrived at Earth about 8 minutes after the flare. The X-rays were generated by loops of material that sprouted above the limb of the Sun.

The flare also kicked up a coronal mass ejection. This cloud of charged particles will expand outward and, in theory, could provide a glancing blow to Earth's magnetic field. It is the CME in a storm that typically causes colorful auroras for high-latitude viewers.

Christopher Balch, a forecaster at NOAA's Space Environment Center, said in a telephone interview at 7 p.m. ET that his team was still trying to pin down the flare's strength. He said effects from the eruption could be felt sometime Thursday but that it did not appear likely to create a major storm. Forecasters were still analyzing the event, however.

Auroras were spotted as far south as Texas during last week's storms.

The first of three other major flares that erupted Sunday and Monday passed early Tuesday with little effect. Sunday's flare was an X8.

All four flares this week were generated by sunspots that are rotating out of view, around the right side of the Sun. Solar activity is expected to decline in the days ahead. It is possible the sunspots will re-emerge in about two weeks. Scientists cannot say if they will grow, maintain their intensity, or diminish as they travel around the back side of the Sun.

The strongest flare in the series, prior to today, was an X17 event on Oct. 28, which generated severe geomagnetic storming when it blew past Earth less than 24 hours later.