Sun's Unusual Activity Produces Impressive Auroras
ANCHORAGE, Alaska (Sept. 18) - A huge sunspot has been blasting Earth with magnetic clouds for weeks, producing some of the most vibrant and visible summertime auroras in years, according to NASA scientists.
Scientists say the magnetic flare-ups from Sunspot 798 will last at least through Friday.
"It is a fairly large geomagnetic storm that we've had over the past 24 hours, and it should continue a little while longer," said aurora researcher Dirk Lummerzheim, at the Geophysical Institute at the University of Alaska Fairbanks.
Skywide northern lights have awed Alaskans since last week and produced red displays as far south as Arizona.
A North Pole photographer has posted a dazzling picture of a display on the Geophysical Institute's online aurora forum, the Anchorage Daily News reported.
The shimmering green light came courtesy of Sunspot 798, which sent a gusting magnetic cloud hurtling toward Earth at more than a million miles per hour.
Sunspots are planet-sized splotches formed by the sun's roiling magnetic field.
The sunspots become unstable and explode, producing flares and propelling charged particles and radiation into space.
Sunspot activity can produce a geomagnetic storm that makes regular daily auroral activity much more visible than usual.
Solar scientists say the sun is supposed to be in the quiet phase of its 11-year cycle, with sunspot activity close to minimum.
But the year has so far produced four severe geomagnetic storms and 15 extreme flares.
"The sunspots of 2005, while fewer, have done more than their share of exploding," said solar physicist David Hathaway, of the National Space Science and Technology Center in Huntsville, Alabama.
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Big Sunspot Group Spawns Flares, Auroras by Alan M. MacRobert
(Updated Sept. 16). It's been an amazingly busy week for solar observers, considering that we're several years past the peak of the 11-year sunspot cycle. During the last nine days, a large, intensely active sunspot complex known as Region 10808 (or 808 for short) has exploded with nine X-class flares and many smaller M-class flares. These have altered the near-Earth environment and disrupted radio communications, and they set off beautiful auroras over much of North America on the morning of the 11th.
The spot group itself is large enough to see with the unaided eye through a
safe solar filter. The Sun's rotation has carried it to the western side of the Sun's disk as of the 16th, and will carry it out of sight around western limb on about the 21st.
Sunspot region 10808 (formerly known as 10798)
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