The "photo" image shown below was posted today on Facebook by Fifth Star Labs. It shows the accumulation of one year's worth of solar activity in one photo image.

So, I see that this solar activity which I assume to be sun spots, solar flairs, CME sources, and other magnetic storm phenomena appear in a belt on both sides of the equatorial plane of the Sun. Now, I assume that all of this activity is rooted in magnetic field disturbances or activity so there must be something about the magnetic field shape, position, or whatever causing this. Maybe. I know very little about the magnetic field of the Sun.

So, is there a good explanation for this activity being within this band and not including the "polar" regions (and, here I am assuming those are polar regions of a rotating sphere, I am not even sure of that).

Fifth Star Labs Image of Solar Activity

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    $\begingroup$ You would surely get a better mileage asking this question on astronomy.stackexchange.com $\endgroup$ – user154997 Jul 5 '17 at 16:54
  • $\begingroup$ The magnetic field of the Sun is chaotic, which isn't much help for your understanding. However, the Sun rotates, meaning that the linear velocity of the fluid is highest toward the equator. Maybe this contributes to the behavior? $\endgroup$ – probably_someone Jul 5 '17 at 17:48
  • $\begingroup$ @probably_someone The magnetic field patterns in the solar cycle are not chaotic and have been studied for about 400 years. $\endgroup$ – Rob Jeffries Jul 5 '17 at 18:55
  • $\begingroup$ @RobJeffries The solar cycle is periodic with periods much longer than a year, as shown in the answer by David Hammen. The photo above integrates only one year of solar activity, and thus is asking about short-to-medium-term dynamics, which are chaotic. $\endgroup$ – probably_someone Jul 5 '17 at 19:03
  • $\begingroup$ No, not chaotic. Utterly predictable that the magnetic activity occurs at low latitudes. We obviously have a different definition of chaos. @probably_someone $\endgroup$ – Rob Jeffries Jul 5 '17 at 19:09

This is a picture of our Sun after a few years after the peak of a solar cycle. The picture would be quite different a few years prior to the peak. Then you would see a broad band of reduced activity near the equator, with peaks near 30 or so degrees north and south latitude. Where sunspots occur varies over the course of a solar cycle. This is portrayed below.

Sunspot butterfly diagram, from 1870 to 2015

This looks a bit like a swarm of butterflies. Edward Maunder discovered this over a hundred years ago. The cause remains unknown, but it most certainly is connected with the Sun's magnetic field and how it varies over the eleven year solar cycle.

  • $\begingroup$ David, you could point out that part of the reason sunspots occur in this latitude range is because there is more shear flow, which causes fields to coalesce into localized regions. The localized regions are then higher in field intensity, which pushes out hotter particles, thus why sunspots appear darker. $\endgroup$ – honeste_vivere Jul 6 '17 at 15:04
  • $\begingroup$ The more I think about the magnetic fields in the Sun, the more different they must be from the Earth's. Given that the Sun does not have a mostly iron rotating core, it's magnetic fields must be due to currents of charged particles given the sun is a plasma (I think). And, these currents are definitely more affected by the rotational forces of the Sun (again, I think). What I need is a good resource (e.g. book, papers) on the Sun to learn more. $\endgroup$ – K7PEH Jul 6 '17 at 15:27
  • $\begingroup$ @K7PEH - The Sun's magnetic fields are certainly very different than the Earth's. For instance, the higher order multipole moments matter much more for the Sun's fields while the Earth's is mostly dominated by the dipole moment. The source, however, is kind of similar in that both are thought to be driven by a dynamo process. $\endgroup$ – honeste_vivere Jul 7 '17 at 15:06

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