The effects of coronal mass ejections typically last for about 24 hours, waning as the storm gradually passes.
Record output
The outburst was generated by Sunspot 484, one of a trio of unusually large sunspots that generated a record-breaking string of 10 major (X-class) solar flares in late October and early November. The spots then rotated around the back side of the Sun.
All three are again on the visible disk of the Sun, with No. 484 front and center and facing squarely at Earth.
Sunspot 484 has shrunk considerably compared to when it was on the face of the Sun last time, but it is currently the one most threatening because of its position. It has developed a complex magnetic field, according to the NASA-run web site Spaceweather.com. That suggests it has the potential for a major solar flare in the days ahead.
Sunspots 486 and 488 have just come into view on the left limb of the solar system's central star in the past two days. Last time around, they were as big as Jupiter. Scientists are just getting a look at them this time and it appears they have maintained much of their size.
"It looks like both regions still have some punch," said Paal Brekke, deputy project scientist for the SOHO spacecraft, which monitors solar activity.
Rare trio
Sunspots are cooler regions of the Sun were pent-up magnetic energy can erupt, kicking out radiation and superheated gas.
Rarely have scientists witnessed three sunspots so large and powerful on the face of the Sun at once. In fact, it happens about every 10 years, said solar physicist David Hathaway of NASA's Marshall Space Flight Center.
But the last two times a big trio appeared -- in February 1989 and July 1981 -- the Sun was near the maximum of its 11-year cycle of activity, Hathaway told SPACE.com. Right now the Sun is two or three years past peak activity and on its way to a low point in another three years or so.
"The surprise this time is where it came in the cycle," Hathaway said.
For all three spots to maintain their size during a complete revolution of the Sun is not so unusual, Hathaway said. The Sun rotates once every 25 days at its equator. "When they're this big, it takes one or two or even more rotations before they get smaller," he said.
