Sunspot update September 2018: Minimum!

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NOAA yesterday released its monthly update of the solar cycle, covering sunspot activity for September 2018. As I have done every month since this website began in July 2011, I am posting it below, annotated to give it some context.

Sunspot activity on the Sun in September dropped slightly from August. More significantly, the activity continues to match closely the weak activity seen in 2008, when the Sun last went through its last solar minimum. We are unquestionably now in the new minimum, and its arrival in the past few months makes the now-ending solar cycle about one to two years shorter than predicted.

September 2018 sunspot activity

The graph above has been modified to show the predictions of the solar science community. The green curves show the community’s two original predictions from April 2007, with half the scientists predicting a very strong maximum and half predicting a weak one. The red curve is their revised May 2009 prediction.

As I noted last month, the NOAA graph is now getting very close to its right edge, which ends in December 2019. They will very soon have to update this graph so that it can take us into the next solar cycle.

What that new cycle will bring will be the next mystery. I have been following this cycle now since its unusual beginning, with a solar minimum much much longer and more inactive than any solar scientist had ever expected. We can only guess at the surprises the Sun will give us in the coming decade, especially since the science of solar sunspot activity remains superficial and in its infancy. We do not really understand why the Sun’s activity fluctuates. Nor do we understand why it periodically stops producing sunspots for long periods, resulting in what solar scientists call a grand minimum.

There are some scientists who think another grand minimum is coming. We shall have to wait and see. I certainly am going to follow their upcoming observations, as this work remains one of the great scientific studies humans are presently pursuing.



  • Phill O

    Bob, you wrote “as this work remains one of the great scientific studies humans are presently pursuing.”

    I am thinking this may be one of the great understatements of the decade! However, that is consistent with your mindset of not overplaying a hand due to our lack of knowledge.

  • Phill O

    Does anyone know if weather stations record or monitor the sun’s energy reaching their sites? If so, where can I find an historical file for data? I am thinking of W/m2.

  • Max

    Weather stations only monitor the weather. (temperature and humidity, ect.)
    Total solar irradiance (TSI) is useful for such things as the solar race in Australia with EARTH at its closest approach to the sun. Or where to locate solar panels where they are the most effective. (every solar panel manufacture can tell you your TSI for your location)
    Satellites measure the suns intensity directly giving unbiased measurement. Several do this like Soho and GLORY…

    A short paragraph,
    “During periods of intense solar activity—characterized by peaks in sunspots, flares, and hotspots called faculae—TSI increases by approximately a tenth of a percent. Overall, TSI varies by approximately 0.1 percent—or about 2 watts per square meter between the most and least active part of an 11-year solar cycle.”

    Two watts (think night light) per meter squared is not much. Au. solar race usually receives 1000 W per meter or the equivalent of 10, 100 W lightbulbs in Square yard. The sun has never varied more than 1% of this total. This is why the weather is associated with cosmic radiation being attracted by earths magnetic field which increases during solar minimum. For some reason it causes more humidity which reflects more sunlight causing it’s cooler/wetter weather. It also causes more carbon 14. (A big change in atmospheric chemistry affecting pH)
    It will be interesting to have real time measurements of this true weather changing event if the prelonged solar minimum occurs.

  • Phill O

    Thanks Max. I was wondering the TSI at the earths surface as relates to smoke adsorption higher up. This relates to how much heat the earth collects vs clear days. This particular fall in Alberta has seen significant loss of heating both due to smoke from BC fires and cloud cover. Overall, is there an index for how much is the earths total collected energy?

    I believe the 0.1% number is not a constant at all wavelengths, is it not?

  • Phill O today had a TCI Thermosphere Climate Index. Something like this is what I was getting at. This may be a great new index. Another index where the surface measurement might be helpful to relay info on cloud and pollution affects!

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