Thank you Kurt, that was very interesting. Just what I needed to wake me up this morning! :) Julie ----- Original Message ----- From: "Kurt Fisher" <fisherka@csolutions.net> To: <utah-astronomy@mailman.xmission.com> Sent: 2007-07-26 19:45 Subject: [Utah-astronomy] For Saturday's Sun Party - Will solar minimum everarrive?

We seem to be in year 7 of the 11 year solar cycle - and solar minimum has yet to arrive. -

http://sidc.oma.be/html/wolfmms.html

- and the prediction looks like it will not turn to the rising phase until the end of this year, almost 7 years after the last maximum -

http://sidc.oma.be/html/wolfjmms.html

- but then will rapidly rise to the next maximum in just three years in 2011.

http://solarscience.msfc.nasa.gov/images/ssn_predict_l.gif

This page -

http://solarscience.msfc.nasa.gov/predict.shtml

- references a paper on the shape of the curve of past cycles as the basis for predicting future cycles -

Hathaway, Wilson, and Reichmann Solar Physics; 151, 177 (1994) http://solarscience.msfc.nasa.gov/papers/hathadh/HathawayWilsonReichmann1994...

Among the things that the authors note are:

1) Solar cycles are not strictly periodic and do not follow a lockstep 11 year pattern. "[W]hile the average cycle length (minimum to minimum) is about 11 years, individual cycles vary in length from 9 to 14 years."

2) "Further, smaller cycles tend to rise to maximum more slowly than larger cycles (the Waldmeier effect)."

I'm not sure what a "large amplitude" cycle means - what's big, medium, and small? But this chart of the cycles back to 1750 will give you an idea:

http://sidc.oma.be/html/wolfaml.html

3) "Most cycles shows substantial asymmetry, with the rise to maximum being faster than the fall to minimum."

4) The last few cycles have been anomalous and show chaotic behavior.

The fact that we are into seven years since the last maximum seems to be norm, not the exception.

But this is probably a good thing for club members. It has given more time for club members to buy and become proficient with the ubiquitous PSTs. More solar amateurs are taking up and becoming proficient in solar imaging. They'll be ready for the next maximum. Looks like things are shaping up for a real solar Renaissance, observationally speaking, at the next max.

- Kurt

See also http://solarscience.msfc.nasa.gov/SunspotCycle.shtml

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