Dr Osborn has an interesting career in addition to being a Science Fiction writer.
A veteran of more than 20 years in the civilian space program, as well as various military space defense programs, she worked on numerous space shuttle flights and the International Space Station and counts the training of astronauts on her resum�. Her space experience also includes Spacelab and ISS operations, variable star astrophysics, Martian aeolian geophysics, radiation physics, and nuclear, biological, and chemical weapons effects.
She posted the following on Jerry Pournelle’s Chaos Manor blog:
1) Yes indeed, I have been following sunspot numbers for many years now. And while sunspot numbers have been decreasing steadily for several cycles to date, the current dearth is very unusual — especially for this point in the cycle — and, to quote my favorite Vulcan, “Fascinating.” I am definitely continuing to keep an eye on the activity, or rather lack thereof.
2) There is a new model out (the “double-dynamo” model of the solar interior), only about 2 years old, which does a reasonable (though not perfect; it’s still not complex enough, IMHO) job of predicting extended solar minima, as well as the somewhat unusual “two-hump” shapes of recent solar cycles (when sunspot numbers vs. time are plotted). This model is predicting an extended minimum beginning in about 10-15 years, and this roughly matches my own considerations based on observation. (I think I referenced the model’s prediction in my original email, which you excerpted, though I may not have been clear enough; sometimes I forget not everyone is in the astronomical field, hence not familiar with the things I am. My bad.) If it is, indeed, not complex enough (as I strongly believe), then it may be that said extended minimum may begin sooner or later than predicted. The current rather precipitous decrease in sunspot numbers so soon after a solar max — which was itself somewhat paltry — may indicate an early start…or not. We will have to wait and see.
3) The “Little Ice Age” was actually a significantly extended cool period lasting several centuries, and no less than FOUR extended minima occurred during its “tenure.” These include, in order, the Wolf, the Spörer, the Maunder, and the Dalton minima. These extended minima were not all of the same “depth,” in that the minimum numbers of sunspots were not the same across all of them — the Maunder was far deeper than the rest — but as I mentioned previously, there are indications that we are hitting numbers in the range of the Dalton already. [Note that, during the Maunder Minimum, sunspots became so rare, that a grand total of only ~50 were observed over 28 years — this corresponds roughly to two and a half solar cycles. In a “normal” cycle, we would expect to see around 50,000 sunspots in that same timeframe, some three orders of magnitude more.]
4) The fact that, as sunspot numbers go down, the overall energies output by the Sun also go down is an indication that, in this instance, correlation may well equal causation, at least to some degree. Add in a few large volcanic eruptions to complicate matters — and there usually ARE some large volcanic eruptions in such timeframes, as a matter of course — and it may well prove interesting times ahead, as well as in the past.
5) The fact that cosmic ray fluxes are increasing is further indication that solar activity is decreasing, as the solar wind normally tends to provide a shield of some (relative) substance against cosmic rays, which originate outside our solar system, mostly from galactic sources (supernovae, active galactic nuclei, etc.). But as solar activity declines, the solar wind also declines, and so too would the cosmic ray flux increase, as the plasma which shields us from its entrance into the inner solar system decreases. (We still have the magnetosphere shielding us.)
I’m simplifying, of course; things are always more complex than meets the eye. But given the steady decrease in numbers for a good 3 or more cycles now (with considerable fluctuation for several cycles before that), I will be surprised if, at some time in the next few cycles, we do not enter an extended minimum, even if only of moderate depth. And it really isn’t a matter of “if,” but of when. Many variable star astronomers (and that’s what I studied in school — spotted variables, no less) consider that the Sun is at the very least borderline variable; some consider it outrightly so. I tend to fall in the latter camp; it all depends on the percentage of variability, and we are only now obtaining the kind of data we need to determine that. But it doesn’t actually take much.
Of course, only time will be the true validation if we are going to have another Grand Minimum. Readers thoughts?