The new study, led by Sami Solanki
of the Max Planck Institute
in Germany, employed a novel approach to pinning down
sunspot activity going back 11,400 years:
Cosmic rays constantly bombard Earth's atmosphere.
Chemical interactions create a fairly constant source
of stuff called carbon-14, which falls to Earth and
is absorbed and retained by trees. But charged particles
hurled at Earth by active sunspots deflect cosmic rays.
So when the Sun gets wild, trees record less carbon-14.
While trees don't typically live more than a few hundred
years or perhaps a couple thousand, dead and buried
trees, if preserved, carry a longer record, "as
long as tree rings can be identified," said Manfred
Schuessler, another Max Planck
Institute researcher who worked on the study.
The study's finding: Sunspot activity has been more
intense and lasted longer during the past 60 to70 years
than at anytime in more than eight millennia.
Polar lights from increased sunspot activity
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