Sun makes history - 1st spotless month in Century
- From: Old Tom <rascal_51@xxxxxxxxxxx>
- Date: Mon, 1 Sep 2008 15:21:30 -0700 (PDT)
The record-setting surface of the sun. A full month has gone by
without a single spot (Source: Solar and Heliospheric Observatory
(SOHO))
The sun has reached a milestone not seen for nearly 100 years: an
entire month has passed without a single visible sunspot being noted.
The event is significant as many climatologists now believe solar
magnetic activity – which determines the number of sunspots -- is an
influencing factor for climate on earth.
According to data from Mount Wilson Observatory, UCLA, more than an
entire month has passed without a spot. The last time such an event
occurred was June of 1913. Sunspot data has been collected since 1749.
When the sun is active, it's not uncommon to see sunspot numbers of
100 or more in a single month. Every 11 years, activity slows, and
numbers briefly drop to near-zero. Normally sunspots return very
quickly, as a new cycle begins.
But this year -- which corresponds to the start of Solar Cycle 24 --
has been extraordinarily long and quiet, with the first seven months
averaging a sunspot number of only 3. August followed with none at
all. The astonishing rapid drop of the past year has defied
predictions, and caught nearly all astronomers by surprise.
In 2005, a pair of astronomers from the National Solar Observatory
(NSO) in Tucson attempted to publish a paper in the journal Science.
The pair looked at minute spectroscopic and magnetic changes in the
sun. By extrapolating forward, they reached the startling result that,
within 10 years, sunspots would vanish entirely. At the time, the sun
was very active. Most of their peers laughed at what they considered
an unsubstantiated conclusion.
The journal ultimately rejected the paper as being too controversial.
The paper's lead author, William Livingston, tells DailyTech that,
while the refusal may have been justified at the time, recent data
fits his theory well. He says he will be "secretly pleased" if his
predictions come to pass.
But will the rest of us? In the past 1000 years, three previous such
events -- the Dalton, Maunder, and Spörer Minimums, have all led to
rapid cooling. One was large enough to be called a "mini ice age". For
a society dependent on agriculture, cold is more damaging than heat.
The growing season shortens, yields drop, and the occurrence of crop-
destroying frosts increases.
Meteorologist Anthony Watts, who runs a climate data auditing site,
tells DailyTech the sunspot numbers are another indication the "sun's
dynamo" is idling. According to Watts, the effect of sunspots on TSI
(total solar irradiance) is negligible, but the reduction in the solar
magnetosphere affects cloud formation here on Earth, which in turn
modulates climate.
This theory was originally proposed by physicist Henrik Svensmark, who
has published a number of scientific papers on the subject. Last year
Svensmark's "SKY" experiment claimed to have proven that galactic
cosmic rays -- which the sun's magnetic field partially shields the
Earth from -- increase the formation of molecular clusters that
promote cloud growth. Svensmark, who recently published a book on the
theory, says the relationship is a larger factor in climate change
than greenhouse gases.
Solar physicist Ilya Usoskin of the University of Oulu, Finland, tells
DailyTech the correlation between cosmic rays and terrestrial cloud
cover is more complex than "more rays equals more clouds". Usoskin,
who notes the sun has been more active since 1940 than at any point in
the past 11 centuries, says the effects are most important at certain
latitudes and altitudes which control climate. He says the
relationship needs more study before we can understand it fully.
Other researchers have proposed solar effects on other terrestrial
processes besides cloud formation. The sunspot cycle has strong
effects on irradiance in certain wavelengths such as the far
ultraviolet, which affects ozone production. Natural production of
isotopes such as C-14 is also tied to solar activity. The overall
effects on climate are still poorly understood.
What is incontrovertible, though, is that ice ages have occurred
before. And no scientist, even the most skeptical, is prepared to say
it won't happen again.
Article Update, Sep 1 2008. After this story was published, the NOAA
reversed their previous decision on a tiny speck seen Aug 21, which
gives their version of the August data a half-point. Other
observation centers such as Mount Wilson Observatory are still
reporting a spotless month. So depending on which center you believe,
August was a record for either a full century, or only 50 years.
.
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