What’s Wrong with the Sun? (Nothing)

The headline comes from this article at NASA, sent in by reader “Mike D.”

The gist of the article is “that there’s nothing to report.” Says David Hathaway:

“There have been some reports lately that Solar Minimum is lasting longer than it should. That’s not true. The ongoing lull in sunspot number is well within historic norms for the solar cycle.”…Although minima are a normal aspect of the solar cycle, some observers are questioning the length of the ongoing minimum, now slogging through its 3rd year…Hathaway has studied international sunspot counts stretching all the way back to 1749 and he offers these statistics: “The average period of a solar cycle is 131 months with a standard deviation of 14 months. Decaying solar cycle 23 (the one we are experiencing now) has so far lasted 142 months–well within the first standard deviation and thus not at all abnormal. The last available 13-month smoothed sunspot number was 5.70. This is bigger than 12 of the last 23 solar minimum values.”

In summary, “the current minimum is not abnormally low or long.”

Let’s take a look at the actual data and see if the statements about the “normalness” of the sunspot number are accurate. And let’s keep in mind the real reason NASA made this press release, the purpose of which is never directly stated—can you see it?. I’ll come back to this later.

Here is a picture from NASA showing the “Yearly Averaged Sunspot Numbers 1610-2007.”
Sunspots through time

Solar cycle “number 1” peaked around 1760, the cycles and other behaviors before this time are ignored in the official counting. Well, that’s neither here nor there—the labels do not matter—but we should always remember that the sun’s sunspot activity has been taking place for at least 4 to 5 billion years, and we only have measurements on the last 400. Thus we are in a very poor position to say what is “normal” and what is not. We can, however, make statements conditional on the data observed so far.

Hathaway’s analysis starts with cycle number “1” and ignores the previous data, which, given the extended period of low to no sunspots from 1650 to 1700, actually weakens his case. This is because, conditional on all the available evidence, periods of time with no or low sunspots are not that unusual. These quiescent periods are more likely given all the evidence than they are just using the data from 1749. This is true based on the simple observation that all the data has more quiescent periods than does the later half. It is true regardless of the periodicities or other structures present. Because we have seen periods in the past with few or no sunspots is excellent evidence, after all, that we will see these periods in the future.

So why would he purposely ignore evidence that would have strengthened his case? Part of the reason is that there is the possibility that the data before 1749 is measured with error, and so should be discounted somewhat. However, this error is not especially large. The real reason has to do with the “Maunder Minimum” (shown on the graph), the period with few or no sunspots. This period does not fit the probability model Hathaway has in mind, so it is ignored. NASA says this about the Maunder:

For reasons no one understands, the sunspot cycle revived itself in the early 18th century and has carried on since with the familiar 11-year period. Because solar physicists do not understand what triggered the Maunder Minimum or exactly how it influenced Earth’s climate, they are always on the look-out for signs that it might be happening again.

But Hathaway thinks the “quiet of 2008 is not the second coming of the Maunder Minimum.”

Thus we have gone from “For reasons no one understands” to “the solar cycle is progressing normally.” The path from one statement to the other is indeed rocky. This is why I believe Hathaway’s statements are too certain. I believe that periods of low to no sunspots are more likely. I am not, however, disagreeing with Hathaway in the sense that it does not appear that we are in another Maunder: there is only scant, at best, evidence for this.

As a technical note: It is not clear that the uncertainty in length of time in months that the cycles last is best represented by a normal distribution, as used by Hathaway. Ignoring the Maunder makes his approximation a better one, but there is never a good reason to ignore part of the data it does not fit your expectations.

Anyway, back to the real purpose of this press release. Why are people so interested in the length of the solar cycle? Easy. Because for years, most climatologists insisted that the role the sun plays in the climate was minimal. That is to say, changes in the behavior of the sun were not thought to be related to changes in the Earth’s climate. The sun, which alone supplies all the energy that goes into creating the climate, was thought not to be important. Obviously, this attitude is starting to change. This press release is a tacit admission that some now admit some role of the sun in climatology.

I do not have time to talk here of the actual methods to predict sunspot number, which is an important activity in space weather. But take a look at the first picture in the press release and see if you can not anything odd.


  1. HarryG


    I would like to see your analysis on the periodicity of the sunspot cycle, however as to your question. The oddity that strikes me is the steepness of the prediction for the next cycle. Isn’t it a bit steep based on the available data?



  2. braddles

    That error range on the past count looks rather wide. i wonder what it represents.

    Incidentally, the “sunspot number” is not actually the number of sunspots. It is an index that even includes a fudge factor, and it will normally be a lot higher than the real number of sunspots, unless of course there are none at all like now.

    Hathaway is confident that the next cycle is just about to start and the numbers will start to shoot up within a few months. However, the equivalent prediction from Hathaway from March 2006 said the same thing; I kept a copy and have posted it here.


    According to that, Cycle 24 is already almost 2 years late.

    So a prediction as recent as 2006 already looks woeful. Just how much credibility should we give them now? (Rhetorical)

    It’s worth remembering that sunspot cycles are inherently more predictable than climate.

  3. Luis Dias

    The steepness seems normal to me, because sunspot numbers don’t behave like bell curves, the peak is actually always leaned to the “left”. For instance, the minimum of 96-97 was followed by a peak in 2001. That’s 4.5 years. If we are in the minimum, then 2012-2013 should be a correct prediction, no?

    And the guy’s right. 96-97 to 2008 seems like 11-12 years. Quite on target, if you ask me. So the fuss seems more about trying to find other things to blame the warming rather than CO2, and the sun is in fashion. It’s a neat trick, if one gets to watch antony watt’s page, he makes the case of the sun being quiet for some months and gets a lot of attention. Sometimes he updates it with a disconcerning remark, like, “omg, the sun is shutdown!”, some commenters pander on the wagon of “omg, those creeps are forgetting / ignoring the sun, how stupid they are!!” and they keep up the charade for as long as he can. Naturally, he still has some room to play it, until the 24th cycle climbs again.

    In that time however, the fashion has changed to other event altogether, and everyone has forgotten the sun thingy.

    That’s how it seems to me, my 2 cents.

  4. Luis Dias

    Unless you’re talking about the fact that they have chosen the highest prediction they had made concerning 24th cycle sunspot number’s peak, so that subliminally one would not think that the sun is going down.

    Yeah, that’s probably a rhetorical low jab.

    Image of predictions of sunspot cycle 24 number.

  5. I’m as far from an expert on this as it’s possible to be, but I don’t think the sun supplies all the energy that drives the climate. Certainly it might be counted as such in a simplified model (and all models are simplified one way or another), but if you asked a climatologist if the climate would change if we turned off the Earth’s internal heat tomorrow morning, and I think they would tell you that of course it would.

  6. Roger W. Cohen

    Scafetta and West (Duke University and the Army Research Office) have shown that solar variability has indeed accounted for a major fraction — but not all — of 20th century warming. Perhaps even more interesting is their observation that the noise spectra of solar magnetic cycles and terrestrial climate fluctuations are identical (-2.1) power laws, with no fundamental scale. This points strongly to the two systems being coupled complex systems. Their work is phenomenological so it does not identify the actual physical mechanism for this coupling. We CAN say is that this mechicanism is not contained in the climate models. This is one more reason the models cannot be considered reliable, nor can press releases from agenda-driven agencies.

  7. But take a look at the first picture in the press release and see if you can not anything odd.

    Are you referring to the error bars (the dotted lines) that dip below zero in the late nineties and late aughties?

  8. Mike

    I don?t think the sun supplies all the energy that drives the climate./

    Trying turning it off for two weeks and measure the temperature outdoors.

  9. Bob Koss

    I tried to comment about two hours ago, but evidently the comment didn’t get through. Trying again.

    They state “The last available 13-month smoothed sunspot number was 5.70. This is bigger than 12 of the last 23 solar minimum values.”

    Have there been no changes in observational ability since 1749? If there have been, wouldn’t that make the statement misleading and of no statistical value?

  10. Brian

    Third time trying to get posted since this morning.

    The error range is smaller for the upswing of Cycle 24 despite the variability in recent observations. Where does the new confidence level come from?

  11. Cycle 24 hasn’t arrived yet. We’re still in the lull. Comparing this lull to any past lull is like comparing a ballgame in the fifth inning to previous complete 9-inning games.

    However, it interesting to note that sun is pitching a no-spotter, and concurrently we have just experienced the coldest winter in 20 years. Co-inky-dink? Maybe.

    Here’s a great pick-up line.

    Him: “Do you believe in coincidences?”

    Her: “Yeah, I guess so.”

    Him: “That’s amazing, ’cause so do I !!!”

  12. Basil

    More than the error bars going negative, the are narrower during the forecast period than in the hindcast/historical period. Normally, the uncertainty of a forecast increases out into the future. Hathaway seems to think that he can predict the future with greater certainty than he can explain the past. He should get a patent on that.

  13. I suppose I should point this out, since I primed the pump, so to speak. The confidence lines on the graph reference daily fluctuations in sunspot numbers. The statistic in question (in the article) is solar cycle length. Those are two completely different statistics. The graph does not show solar cycle length, it’s distribution over the last 400 years, or alleged confidence intervals associated with that distribution.

    If we did have that distribution illustrated, we would see that it is not bell-shaped. It is sharply skewed to the right, the skew being the Maunder Minimum, when sunspots were nearly absent for 70 years or so. Since the distribution is not bell-shaped, it is perforce not Gaussian normal.

    Of course, nothing in nature is Gaussian normal, Gaussian normal being a theoretical parametric formulaic equation. It is a wonderful equation with all sorts of interesting properties, but it does not correspond to the “real” world, “real” meaning the physical, chaotic, non-mathematical world of nature. And it follows that “standard deviations from the Gaussian normal” also have no corresponding reality in the “real” world.

    It’s just stat babble, which I am fond of, but know the limitations of, too. And Matt knows them even better and more so. He points out (repeatedly, see his book) that the confidence bred by reliance on standard deviations from the Gaussian normal is poppycock and false certainty. Emperor NASA wears no clothes, statistically speaking.

    That’s what I see, or don’t see to be more precise, in the picture.

  14. Let’s take the analysis a step further. The key question is: how long until we get a full solar maximum again? The answer is not to be found looking at the average, but in looking at the tail of the distribution.

    Similar questions might be, what will be the extreme value of say, the 100-year flood, or the 50-year snowfall? What happens in the extreme case and how frequently does the extreme case arise? Extreme value questions probe the tail of the distribution, not the middle. We wish to map the skewed part, not the hump.

    The average never happens, as Matt has pointed out. The average is just average of all those happenings to right and left of it, or this case to the far right, out in the tail.

    Moreover, the phenomenon of solar sunspot activity is not a roll of the dice. There are factors involved, like solar magnetic strength, solar pole reversal, the solar conveyor belt, gravitational pulls, etc. that influence, or at least correlate temporally, with sunspot activity. So we might possibly get some insight from a model of some kind, like a generalized extreme value regression with weighted measured explanatory factors.

    Bumbling along with the bell-shaped Gaussian curve is so Jr. High. NASA can do better than that.

  15. Robin Starveling

    No one can know that there is nothing wrong with the sun because there is no deductive process leading to that conclusion.

    Many modern people like Hathaway are cognitively impaired because they think that observing many consistent solar cycles determines its normative state when they are in fact missing critical principles.

  16. Luis Dias

    Yeah, I think I got it. The problem with it is the error bars. They assume that they know how the sunspot number graph will look like, and the error bars are only noise bands or something like that. The problem is that those noise bands are assumed visually to be the boundaries of what science can tell about the sunspot cycle, when they are clearly not, for the graph is the highest “prediction” available.The error bars should then be quite wider below the shown curve.

    Am I right? I’m not even close to be a statistician, so what I said probably is dumb.

  17. John

    If this is a duplicate comment, my apologies. It didn’t look like it went through last time. Take this one over the previous, though; I corrected an error in my writing and clarified some other things.

    Here’s what I find odd. I think the thing we are supposed to notice is much more basic than where we commenters have been looking so far.

    In the graphic, it looks like Hathaway is calling for cycle 24 to be unusually short, say, 9 years or so, if we add a generous curve just to the right of the graph’s ending. If we don’t use our imagination like that, his graph would show as little as a 7 year cycle. Both sides of that curve are incredibly steep; it looks like he adjusted the front side without doing much adjustment on the back side.

    I thought normal cycles were supposed to average 11 years +/- 1 year. Let’s assume that Hathaway stands by the assessment of a 9 year cycle 24. I thought that short, strong cycles like the one Hathaway predicts were supposed to lend themselves to unusually active next cycles. Note, though, that even Hathaway is calling for an unusually quiet cycle 25. His graph doesn’t appear to fit his own words.

  18. David Snyder

    One thing that bothers me about cycle 23 is that while it was low compared to recent cycles (post cycle 17) it is still an average to intense cycle in the overall record. Since cycle intensity correlates inversely with cycle length, it ‘should’ have been an 11 yr cycle (132 month) 142 months seems quite out of line.

    Also, there was no single consensus prediction for Cycle 24.
    from http://www.swpc.noaa.gov/ftpdir/weekly/README3
    November 6, 2007

    ISES Solar Cycle Progression and Prediction Displays

    The initial ISES Solar Cycle 24 Prediction was released in April, 2007. The panel charged with determining the prediction was unable to agree on a single solution and have so far provided two predictions. Those two predictions are available here, along with an average of the two predictions. The average is
    currently being used as the official prediction. The ISES panel does not consider this to be an adequate solution. To mitigate this, the lower and upper bounds used with the average cover the range of the two predictions issued by the panel. When the panel converges on a single prediction, the files here will be updated to reflect the new prediction. The two predictions
    issued by the panel can be accessed in the files named Predict_low.txt and Predict_high.txt.

  19. Earle Williams

    I find the quote about the 13-month smoothed count most egregious. If the minimum occurs the month, then the 13-month smoothed count surrounding the minimum would include the count for this month, the count for the prior six months, and the count for the next six months. Hathaway has stated a false comparison. A better estimate of the minimum would be to look at the 7 month smoothed count and compare that to prior minima. Or compare the current 13-month smoothed count with that the values six months prior to to previous minima. If I can find the data online I’ll try and see what a meaningful comparison yields.

  20. The error bars don’t contain the observed results and then get a whole lot thinner in the future.

    Methinks that they are overstating their confidence on what the trends are actually going to be.

    Of course I’ve never taken a stats course so it could be the lines are white when they really should be periwinkle.

  21. Luis Dias

    Come on, mr briggs, you can’t pose a question like that and then leave us mind dumbed at what the answer might be!

    Enlighten us.

  22. George

    While we are reviewing Dr. Hathaway’s predictions lets look at another one.


    In this article from October of 2004, Dr. Hathaway predicts that the solar minumum will occur in Oct of 2006. This would have made SC 23 a short solar cycle. Dr. Hathaway makes this bold statement by looking at the previous 8 solar cycles. (and ignoring all the rest of the historical data which does not fit this theory).

    So without being overly unkind, Dr. Hathaway’s record on short range solar forcasting is a bit weak.

  23. David Snyder

    Solar Cycle predictors have not had a lot of opportunity to to perfect their craft. My recollection of the predictions in the 1980’s is that they were simply an average of the previous cycles, and was significantly low for cycle 22. For Cycle 23 some people claimed to have reasons for prediction – and they were generally high (if I remember right). There is now an opportunity to predict cycle 24 (and the end of cycle 23). But, as the Astrologers say, this is only for entertainment value.

  24. David Archibald

    I started the current solar mania with a paper I published in Energy and Environment in 2006. At the time, I was looking at the range of Solar Cycle 24 amplitude predictions, which ranged from about 40 to Dikpati’s 170. The low end predictions tended to be wavelet derived. Dikpati left it very late in Solar Cycle 23 to make her prediction. I think that a low figure would not have been politically acceptable in NASA. Dikpati ranks above Hathaway and so he couldn’t be seen to be departing too much from her number.

    My reasoning at the time was that if 24 was going to be as weak as some were saying, then 23 was going to be very long, just as 4 was 13.6 years prior to the Dalton Minimum. The first sign that we would be having solar-driven cooling would be a long finish to 23. Now we are in the minimum and the confidence with which the month of minimum can be predicted is increasing by the day. The likely curves of the 23 rundown and the 24 ramp up intersect in July 2009, making 23 at least 13 years long. Yep, we are going to have a repeat of the Dalton Minimum.

  25. Luis Dias

    Mr. David, not trying to be an ass, but isn’t that prediction only based on one type of Dalton minimum? I mean, just because 4 was long and it was followed by DM, it doesn’t compute directly that if 23 is long, then another minimum follows it. I mean, we have only one recorded historical example of that, so the statistical inference is beyond ridiculous.

    So how do you base your certainty of DM repeat, more than this (yet to see) one single coincidence between long 4 and long 23, and how do you solve the everlasting dilemma of correlation being different from causation?

  26. David Snyder

    While the argument based on a single cycle is weak, I am intrigued by the statement “The likely curves of the 23 rundown and the 24 ramp up intersect in July 2009”. Also, the more than 12 year cycles are Cycles: 4,5,6,9. All of these were followed by weak (

  27. David Snyder

    Lets try to continue this …
    the more than 12 year cycles are Cycles: 4,5,6,9. All of these were followed by weak (less than 100 SSN) cycles. The current predictions for the next cycle is the is only the second time predictions have been based on more than numerology. And many will be shown wrong within the next six years. Sit back and enjoy the fallout.

    Based on ftp://ftp.ngdc.noaa.gov/STP/SOLAR_DATA/SUNSPOT_NUMBERS/SMOOTHED.PLT
    Cycle SSN Peak Length Start Peak Date

    1 86.5 11.25 1755.17 1761.42
    2 115.8 9 1766.42 1769.67
    3 158.5 9.25 1775.42 1778.33
    4 141.2 13.66 1784.67 1788.08
    5 48.6 12.59 1798.33 1804.67
    6 48.7 12.41 1810.92 1816.33
    7 71.5 10.59 1823.33 1829.83
    8 146.9 9.58 1833.92 1837.17
    9 132 12.42 1843.5 1848.08
    10 95.2 11.25 1855.92 1860.42
    11 140.3 11.75 1867.17 1870.58
    12 74.6 11.25 1878.92 1883.92
    13 87.9 11.91 1890.17 1894
    14 64.2 11.5 1902.08 1906.08
    15 105.4 10 1913.58 1917.58
    16 78.1 10.09 1923.58 1928.25
    17 119.2 10.41 1933.67 1937.25
    18 151.8 10.17 1944.08 1947.33
    19 200.9 10.5 1954.25 1958.08
    20 110.6 11.67 1964.75 1968.83
    21 164.5 9.75 1976.42 1979.92
    22 158.5 10.16 1986.17 1989.5
    23 120.8 11.67* 1996.33 2000.25
    24 2008
    * length of cycle 23 is a minimum since 24 has not yet started. But I’m almost willing to wager it will be longer than 12 yrs.

  28. David Archibald

    Let’s cut to the chase. There is a correlation between solar cycle length and the temperature in the mid-latitudes of the following cycle. See the paper I gave at the New York conference in March. The relationship is that each year of extra length lowers the temperature in the mid-latitudes of the following cycle by 0.7 degrees C. Relative to the extra short Solar Cycle 22 of 9.6 years, we already have 2.0 degrees of cooling in the bag for next decade.

    Re the curves, see Jan Janssen’s blog “Solaemon” and his graphs of the progression of Solar Cycle 23/24 minimum.

  29. Bart

    Mike D. said: “Of course, nothing in nature is Gaussian normal, Gaussian normal being a theoretical parametric formulaic equation.”

    It’s a lot more than that. Due to the Central Limit Theorem, all processes which are a superposition of many independent subprocesses tend to a Gaussian distribution.

  30. Solar cycle 23 started in May 1996. It isnt finished yet and typically finishes approx. 1 year after solar minimum. If solar minimum was this month (July 2008) then solar cycle 23 would finish August 2009 meaning it would be 13 years and 3 months long which is far from typical.

  31. Terry

    What I find odd is that the article talks about the normal behaviour for long periods of time, but the graph only shows one cycle. A nice way to hide any long term trends.

  32. John

    Hi All,

    I visited this site when Mike D first posted and noticed something else……

    If you look at the prediction graph in the press release you will notice that it’s not the latest official NASA prediction graph.
    If you refer to – http://www.swpc.noaa.gov/SolarCycle/index.html
    You will notice that the prediction was revised by NASA in May 2008 to a much lower prediction than the one used in the press release.

    Why would NASA use the old bigger prediction data in the July press release ?

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