[FrankM]

Two days ago I ran across the July 2004 issue of Natl Geographic and its article about the Sun. They
noted that what we really know about the Sun has been obtained in just the last 20 years. The most
notable feature of the Sun has been its sunspots and their 11 year cycle but I found this is actually
half of the cycle. The following from the UOregon page.

"The number of sunspots reaches a maximum about every 11 years, but successive maxima have
spots with reversed magnetic polarity. Thus the whole cycle is 22 years long."

The Natl Geographic article mentioned that the Sun puts out slightly more heat during sunspot activity,
but there seem to be longer cycles where there are very few sunspots; this also was mentioned in the
UOregon page. The Natl Geographic article noted that the "Little Ice Age" (LIA) was associated with a
period where there were almost no sunspots. Little is known about the Sun's activity during the Medieval
Warming Period which proceded the LIA.

http://zebu.uoregon.edu/~soper/Sun/cycle.htm

[Freethinker]

Originally posted by: FrankM
Two days ago I ran across the July 2004 issue of Natl Geographic and its article about the Sun. They noted that what we really know about the Sun has been obtained in just the last 20 years. The most notable feature of the Sun has been its sunspots and their 11 year cycle

Thanks for the great info. But I want to make sure one part is not confused.

Yes we have learned more about the sun in the last 20 years than the entire time before that.

But we have been aware of the sunspot cycle long before that. I was dealing with it 40 years ago myself because of involvement with RF transmissions. They can be dramatically affected by solar flairs and certain parts of the solar cycle allows for much better distance of the transmission.

[FrankM]

The material from the UOregon page indicates that the Sun's internal processes have very low cyclic
rates, at least to our lifespans. Looking at the intensity plots from 1600 on, it appears there are
cycles within cycles. The dramatic intensity drop centered around 1675 could be a natural cyclic
minimum, but since we don't have enough data we don't know when this will appear again.

It is known there was a Medieval Warming Period (MWP), but nobody was monitoring polar ice or
ocean temperatures or sunspot cycles. We have no way of knowing the current global conditions
also happened in the MWP period (800 to 1200 AD). If you consider 1000 A.D. the center of the
MWP and 1675 about the middle of the Little Ice Age (LIA) you have almost a 7 century cycle, and
we don't know if that is a complete cycle or a half cycle.

I suspect global warming maybe occur periodically, but not because of human activity. If we were
experiencing "global cooling", I would expect the same type of unscientific scare tactics to be used
by politicians to influence public response.