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Dec.
14, 2007: The solar physics community is abuzz this
week. No, there haven't been any great eruptions or solar
storms. The source of the excitement is a modest knot of magnetism
that popped over the sun's eastern limb on Dec. 11th, pictured
below in a pair of images from the orbiting Solar and Heliospheric
Observatory (SOHO).
It
may not look like much, but "this patch of magnetism
could be a sign of the next solar cycle," says solar
physicist David Hathaway of the Marshall Space Flight Center.
Above:
From SOHO, a UV-wavelength image of the sun and a map showing
positive (white) and negative (black) magnetic polarities.
The new high-latitude active region is magnetically reversed,
marking it as a harbinger of a new solar cycle.
For
more than a year, the sun has been experiencing a lull in
activity, marking the end of Solar Cycle 23, which peaked
with many furious storms in 2000--2003. "Solar minimum
is upon us," he says.
The
big question now is, when will the next solar cycle
begin?
It
could be starting now.
"New
solar cycles always begin with a high-latitude, reversed polarity
sunspot," explains Hathaway. "Reversed
polarity " means a sunspot with opposite magnetic polarity
compared to sunspots from the previous solar cycle. "High-latitude"
refers to the sun's grid of latitude and longitude. Old cycle
spots congregate near the sun's equator. New cycle spots appear
higher, around 25 or 30 degrees latitude.
The
region that appeared on Dec. 11th fits both these criteria.
It is high latitude (24 degrees N) and magnetically reversed.
Just one problem: There is no sunspot. So far the
region is just a bright knot of magnetic fields. If, however,
these fields coalesce into a dark sunspot, scientists are
ready to announce that Solar Cycle 24 has officially begun.
Below:
Solar Cycle 23 is coming to an end. What's next? Image credit:
NOAA/Space Weather Prediction Center.
Many
forecasters believe Solar Cycle 24 will be big and intense.
Peaking in 2011 or 2012, the cycle to come could have significant
impacts on telecommunications, air traffic, power grids and
GPS systems. (And don't forget the Northern Lights!) In this
age of satellites and cell phones, the next solar cycle could
make itself felt as never before.
The
furious storms won't start right away, however. Solar cycles
usually take a few years to build to a frenzy and Cycle 24
will be no exception. "We still have some quiet times
ahead," says Hathaway.
Meanwhile,
all eyes are on a promising little active region. Will it
become the first sunspot of a new solar cycle? Stay tuned
for updates from Science@NASA.
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Author: Dr.
Tony Phillips | Production Editor:
Dr. Tony Phillips | Credit: Science@NASA
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