A series of major solar flares occurred beginning on Thanksgiving evening and, after a 3-day trip to Earth, are expected to trigger aurora borealis, or northern lights, as far south as Illinois and Oregon.

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Forecasters say the burst of activity was unlike anything seen in a decade.

The first flare occurred November 23 at 10:02 p.m. MST (05:02 UT), with a second happening ten hours later, on November 24 at 8:13 a.m. MST (24/1513 UT), according to NOAA's Space Environment Center in Boulder, Colo.

As a result, a geomagnetic storm is expected to reach Earth Saturday evening, November 25, or Sunday.

"A drastic increase in the solar wind, or a shock wave, impacts the Earth's magnetic field, and typically signifies the onset of the geomagnetic storm," said NOAA forecaster Bill Murtagh.

Forecasters expect perhaps as many as four shock waves to arrive in a 24-hour period this weekend. Solar activity is likely to continue at moderate to high levels for the next several days.

The effects

Geomagnetic storms travel at a rate of 1-3 million miles per hour. Strong ones like these can cause satellites to experience surface charging and orientation problems and power systems can also be affected. Such storms can also interfere with high frequency radio communications. The initial solar flares already caused radio blackouts on the sunlit side of the Earth for about an hour.

While there have been other strong solar flares during the current peak in the 11-year solar cycle, the Thanksgiving flares were rare in that there was so many in such a short period of time.

"The rapid-fire sequence of events is unlike anything we've seen thus far, during this solar cycle," Murtagh said.

According to forecaster Larry Combs, the danger lies in the duration of the storms. "We've had several flares and coronal mass ejections (CMEs) in the past 36 hours, and if that continues, the constant bombardment of the Earth by the enhanced solar wind, could affect power systems and satellites."

The flares that produced these storms were categorized by forecasters as X-2 events, X being the highest category of flares possible. The flares occurred in the north central area of the Sun, which is expected to continue to be visible for the next seven days. There is, therefore, a distinct possibility of more activity occurring.

"The region that produced these flares continues to grow and increase in complexity," Murtagh said. "In fact, it's almost doubled in size since yesterday."

The solar wind and particles produced as a result of these flares can produce Auroral Borealis, or northern lights as far down as Illinois and Oregon (typically 50 degrees geomagnetic latitude.)

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