A Sunspot!
Published on Sep 24, 2008 at 4:13 pm.
2 Comments.
Filed under Sun.
A few days ago, a sunspot appeared on the Sun. It was a nice one, too. It was a classic bipolar spot group (with one end a magnetic north pole, and the other end a magnetic south pole). A lot of people got excited. After all, the Sun has been in a protracted solar minimum, with many days appearing just blank. Some people have been gloomily predicting another Maunder Minimum (though, with other doom sayers predicting dire consequences to out of control production of greenhouse gases, that might not be a bad thing). I wrote about the solar minimum a while back. At that time, I did not think that the long solar minimum was anything to worry about, and I still don’t. It has to last much longer than this to really start to worry me.
The new sunspot has a magnetic polarity opposite to that of most of the sunspots that we’ve seen the last decade or so. That means that it is likely a sunspot of Cycle 24, the next sunspot cycle. Each sunspot cycle reverses the magnetic polarity of the one before. Another indication of this spot’s membership in Cycle 24 is its location. It formed a long way from the Sun’s equator. That is where sunspots tend to form early in the cycle. As the cycle progresses, more and more sunspots form, and they tend to form closer and closer to the Sun’s equator. E. E. Maunder showed this in his famous “butterfly diagrams” of sunspot latitudes versus time.
This spot also has good timing. We also just heard news that the solar wind is at the lowest level that it has been since we’ve been recording it. Now, I don’t want to make too much of that. No doubt, the correlation between the long minimum and the low solar wind values is more than just coincidence. Correlation does not equal causation, but I think that in this case there may be a connection. But, remember, we’ve only been measuring the solar wind for about 50 years. That is a long time in human life terms, but it is nothing in terms of the Sun. It is not even long in terms of human history. The Sun has only gone through part of 5 solar cycles in that time. Since each one is a bit different, then saying that this is the lowest level in 5 varying cycles sounds a lot different that saying that it is the lowest level in history (which is what a lot of the more sensational headlines have been claiming).
This was a rather small sunspot. It was also pretty short lived. As you can see in the image below from today, it appears basically gone!
That such a small and short lived sunspot should generate so much attention, though, is indicative of how unusual such sunspots have become in this rather long solar minimum. But, despite the visible signs of the sunspot disappearing, the solar active region that gave rise to it is still there. The sunspots are not the cause of all the solar activity, they are a symptom. It is magnetic behavior that gives rise to all the solar activity. And, in the following magnetogram, you can see that the sunspot group still looks like its there, with one end magnetically one way, and the other end magnetically reversed. That is the active region. The dark spots are just a symptom of this, so it is still too early to declare this little sunspot dead, even though it doesn’t stand out in the visual images anymore.
The Sun has not gone into a Maunder minimum yet, as far as I can tell, and I do not believe that it is going to. We’ve got an active 24th Cycle to look forward to, if what I read is correct. In another 5 years, we’ll be wondering what all the fuss was about in 2008 about no sunspots.
-Astroprof
Images courtesy SOHO
Sili on September 25, 2008 at 9:29 am: 1
Thank you for the dilly on the solar wind. I saw the headlines, but thought I’d get a better story from the blogs.
Farmer John on April 9, 2009 at 3:28 am: 2
It’s way into 2009, Maunder minimum yet?