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Sunspot update: February activity declines to predicted values

Time to do another sunspot update. Below is NOAA’s March 1, 2021 monthly graph, showing the Sun’s monthly sunspot activity. It is annotated by me as always to show the previous solar cycle predictions.

February continued the decline of sunspot activity seen in January after a very unusually active November and December. Though the actual sunspot number was more than the prediction, the difference in February was trivial.

February 2021 sunspot activity

The graph above has been modified to show the predictions of the solar science community for the previous solar maximum. The green curves show the community’s two original predictions from April 2007 for the previous maximum, with half the scientists predicting a very strong maximum and half predicting a weak one. The blue curve is their revised May 2009 prediction. The red curve is the new prediction, first posted by NOAA in April 2020.

The high activity at the end of 2020 might be a harbinger of a very active coming solar maximum, or it could be simply an outlier, one of those random events on the edges of the normal pattern. We really won’t know for at least four to six months. By then a pattern for the ramp up to solar maximum will I think begin to become evident.

As for what will happen in the longer term, I think it easiest to simply quote what I wrote last month:

What we do know is that there is no consensus among solar scientists as to what will happen next. The solar scientists from NOAA, as indicated by the red curve above, expect a relatively weak solar maximum, comparable to the weak maximum seen in 2009. Others believe that the upcoming solar maximum will be very strong, as much as two times stronger than NOAA’s prediction. Others had predicted no solar maximum at all, a prediction which now appears to have been wrong.

At this moment we do not know which prediction (weak or strong maximum) will be right. We must simply wait. And regardless neither prediction really understands the fundamentals that cause the solar cycle in the first place. All they are really doing is making best guesses based on past behavior.

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  • Phill O

    Thanks for the ongoing review of solar activity as depicted by the sunspot index.

    While this is a slow process (watching changes in cycles) it seems to me to be an extremely important topic.

  • Phil Berardelli

    Bob, I’ve been watching the solar image on for the past several weeks, following the last prolonged period void of sunspots. There has been activity — e.g., today’s (3/9) number is 12, with a decaying zone to the southeast and a new zone emerging in the northwest of the image. But the sunspots aren’t visible. They require more magnification to identify.

    It occurs to me that back during the previous Maunder Minimum the telescopes trained on the sun had no greater resolving power than what is displayed on that image. So, it’s possible the sun was exhibiting the same amount of activity back then, but observers weren’t able to record the tiniest sunspots.

    That isn’t to say we’re in a new grand minimum, but it’s possible. In any event, when I was covering the topic, the solar scientists I contacted were predicting the phenomenon to begin around 2030. It might be starting up early.

  • Phil Berardelli: I’ve read a number of papers that proposed the same thing you do. However, in November and December we definitely had strong enough activity to have been spotted by those first telescopes in the 1600s.

    The bottom line remains: No solar scientist in the world has the faintest understanding of the actual reasons the Sun’s dynamo causes these cycles. All they do is predict based on past events. With such a limited understanding, no prediction is really nothing more than a guess.

  • Phil Berardelli

    Bob, I absolutely agree. Your admirable and dogged work about “the uncertainty of science” should show anyone with an open mind that what we don’t know still vastly outweighs what we know about so many subjects, including that middling star on which we owe our existence. Nevertheless, the instruments available during the last solar minimum could not resolve many of the sunspots our modern technology can identify.

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