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Sunspot update for May 2018: Solar activity hangs on

NOAA yesterday posted its monthly update of the solar cycle, covering sunspot activity for May 2018. As I do every month, I have annotated the graph and posted it below.

The small uptick in sunspots that we saw in April after the low in March continued.


May 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. The yellow line compares the present activity with the activity during solar minimum in 2008 and 2009.

In a sense, the increased activity in May was less a return to an active Sun and more a reflection of the Sun’s 27-day rotation period. I have noted this previously but it bears repeating. We count sunspots by the number seen daily on the visible hemisphere of the Sun. Since it is not unusual for sunspot activity to be unevenly distributed across the entire solar globe, it often happens that, during the time when sunspot activity is weak but still occurring, one hemisphere will be blank while the other has sunspots. As the Sun rotates we therefore go through a two week period with no sunspots followed by a two week stretch with increased activity.

SILSO graph, June 4, 2018

This happened in May, as shown by the SILSO graph on the right. While a majority of the Sun’s surface had some sunspots in May, there was a week-long period mid-month when no sunspots were visible. It was at this time that the hemisphere that happened to be less active was facing us.

That quiet period ended on May 20th. Based on the Sun’s 27-day rotation period, you could then predict that a quiet period would next return around two weeks later, around June 1st. And lo and behold, if you look at the graph on the right you will see that on June 3rd the Sun returned to a blank state once again.

Obviously, this type of prediction is very superficial and explains nothing. Moreover, it is reliable only for short periods, as sunspot activity on the surface eventually shifts about so that no specific hemisphere of the Sun remains blank for long. Nonetheless, the fact that about half the Sun’s surface is now routinely blank is another indication that we are heading toward solar minimum, and it looks like we shall reach it, based on the first graph above, sometime late this year or early in 2019. This will make this solar cycle a short ten-year-long cycle. It will also be a weak cycle. This is unprecedented, as in the past short cycles were always more active, not less.

The Sun continues to baffle, and exhibit behavior that we have not seen in more than three hundred years, since the last Grand Minimum.

Pioneer cover

From the press release: From the moment he is handed a possibility of making the first alien contact, Saunders Maxwell decides he will do it, even if doing so takes him through hell and back.

 
Unfortunately, that is exactly where that journey takes him.

 
The vision that Zimmerman paints of vibrant human colonies on the Moon, Mars, the asteroids, and beyond, indomitably fighting the harsh lifeless environment of space to build new societies, captures perfectly the emerging space race we see today.

 
He also captures in Pioneer the heart of the human spirit, willing to push forward no matter the odds, no matter the cost. It is that spirit that will make the exploration of the heavens possible, forever, into the never-ending future.

 
Available everywhere for $3.99 (before discount) at amazon, Barnes & Noble, all ebook vendors, or direct from the ebook publisher, ebookit. And if you buy it from ebookit you don't support the big tech companies and I get a bigger cut much sooner.

One comment

  • Phill O

    “Obviously, this type of prediction is very superficial and explains nothing.”

    Well, not quite true! It does explain the scatter in data near solar minimum, and that we need to remember that solar minimum has not yet come.

    However, the whole solar sun spot cycle is just one indicator for “something” is going on in solar dynamics. We are having a treasure trove of data right now, unprecedented in history: a possible chance to document what happens during a grand minimum.

    As with any research, as some questions are answered, many more come to “light”.

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