Backward Sunspot

http://science.nasa.gov/headlines/y2006/15aug_backwards.htm

Backward Sunspot
NASA Science News

August 15, 2006: On July 31st, a tiny sunspot was born. It popped up
from the sun's interior, floated around a bit, and vanished again in a
few hours. On the sun this sort of thing happens all the time and,
ordinarily, it wouldn't be worth mentioning. But this sunspot was
special: It was backward.

"We've been waiting for this," says David Hathaway, a solar physicist
at the Marshall Space Flight in Huntsville, Alabama. "A backward
sunspot is a sign that the next solar cycle is beginning."

"Backward" means magnetically backward. Hathaway explains:

Sunspots are planet-sized magnets created by the sun's inner magnetic
dynamo. Like all magnets in the Universe, sunspots have north (N) and
south (S) magnetic poles. The sunspot of July 31st popped up at solar
longitude 65o W, latitude 13o S. Sunspots in that area are normally
oriented N-S. The newcomer, however, was S-N, opposite the norm.

A picture is worth a 1000 words. In the magnetic map of the sun, below,
N is white and S is black. The backward sunspot is circled:

[Image]
Above: A SOHO magnetogram of the sun. July 31, 2006.

This tiny spot of backwardness matters because of what it might
foretell: A really big solar cycle.

Solar activity rises and falls in 11-year cycles, swinging back and
forth between times of quiet and storminess. Right now the sun is
quiet.
"We're near the end of Solar Cycle 23, which peaked way back in 2001,"
explains Hathaway. The next cycle, Solar Cycle 24, should begin "any
time now," returning the sun to a stormy state.

Satellite operators and NASA mission planners are bracing for this next
solar cycle because it is expected to be exceptionally stormy, perhaps
the stormiest in decades. Sunspots and solar flares will return in
abundance, producing bright auroras on Earth and dangerous proton
storms
in space: full story
<http://science.nasa.gov/headlines/y2006/10mar_stormwarning.htm>.

Solar Cycles: Past and FutureBut when will Solar Cycle 24 begin?

"Maybe it already did--on July 31st," says Hathaway. The first spot of
a
new solar cycle is always backwards. Solar physicists have long known
that sunspot magnetic fields reverse polarity from cycle to cycle. N-S
becomes S-N and vice versa. "The backward sunspot may be the first
sunspot of Cycle 24."

It sounds exciting, but Hathaway is cautious on several fronts:

First, the sunspot lasted only three hours. Typically, sunspots last
days, weeks or even months. Three hours is fleeting in the extreme. "It
came and went so fast, it was not given an official sunspot number,"
says Hathaway. The astronomers who number sunspots didn't think it
worthy!

Second, the latitude of the spot is suspicious. New-cycle sunspots
almost always pop up at mid-latitudes, around 30o N or 30o S. The
backward sunspot popped up at 13o S. "That's strange."

These odd-isms stop Hathaway short of declaring the onset of a new
solar
cycle. "But it looks promising," he says.

Even if Cycle 24 has truly begun, "don't expect any great storms right
away." Solar cycles last 11 years and take time to build up to fever
pitch. For a while, perhaps one or two years, Cycle 23 and Cycle 24
will
actually share the sun, making it a hodgepodge of backward and forward
spots. Eventually, Cycle 24 will take over completely; then the
fireworks will really begin.

Meanwhile, Hathaway plans to keep an eye out for more backward
sunspots.

zagami{baalke}335:

.

Quantcast