# Our sun to soon reverse its magnetic field

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1. Aug 7, 2013

### Naty1

A four minute video from NASA

Let's hope the climate scientists start talking with the solar scientists.

2. Aug 7, 2013

### Greg Bernhardt

Why? What are the consequences of the switch?

3. Aug 7, 2013

### HallsofIvy

Staff Emeritus
Well, if it happens every 11 years, the consequences can't be too dramatic!

4. Aug 8, 2013

### Naty1

Here is a link to some NASA 'news'....

It is rather easy to pick some titles possibly related to changes in the magnetic field of the sun and our solar system heliosphere. See the left hand panel of subjects here:

http://science.nasa.gov/science-news/science-at-nasa/2013/08mar_solarwind/

Regarding the solar wind,
The article outlines one theory.

Other possible effects of magnetic field changes in the sun are changes in the solar wind impacting our upper astmosphere. Maybe our own magnetic field? And coronal mass ejections, like the one that recently just missed earth, would also seem to be affected by major magnetic field changes. Such effects would seem to have possible long term consequences here on earth.

5. Aug 8, 2013

### Dotini

Cosmic rays are also affected. These are high-energy particles accelerated to nearly light speed by supernova explosions and other violent events in the galaxy. Cosmic rays are a danger to astronauts and space probes, and some researchers say they might affect the cloudiness and climate of Earth. The current sheet acts as a barrier to cosmic rays, deflecting them as they attempt to penetrate the inner solar system.
http://science.nasa.gov/science-news/science-at-nasa/2013/05aug_fieldflip/

"some researchers" I think refers to CERN and Henrik Svensmark's cloud chamber experiments of a few years ago.

Last edited: Aug 8, 2013
6. Aug 8, 2013

### D H

Staff Emeritus
More satellites fall out of the sky.

The switch occurs just around solar max, when solar activity is at its highest. While the effects of the solar cycle on climate and weather are perhaps dubious, the effects on the upper atmosphere is well known. All that solar activity makes the upper atmosphere puff up like a balloon, dramatically increasing drag on satellites on low Earth orbit.

7. Aug 8, 2013

### Naty1

I just checked and it looks like climate change discussions are still prohibited in these forums.

8. Aug 8, 2013

### davenn

Tis a good thing that this solar max is one of the lowest in the last 100 years
It will give the satellites a lesser impact than in the last couple of solar max's
Its also been suggested that the next solar max could be even lower wonder if we will see another
Maunder Minimum. The last one produced a mini ice age throughout much of the nthrn hemisphere.
from wiki...

Dave

9. Aug 8, 2013

### jackmell

Why is it changing? Can we entertain that or no? Is it changing for basically, dynamically speaking at least, for the same reasons the earth's magnetic field changes? For example, the equations which describe the fluctuations of the earth's magnetic field, are they similar to equations which model the sun's changing polarity? Can we do a side-by-side comparison of the two sets of equations and find similarities?

10. Aug 8, 2013

### davenn

why is what ( specifically) changing ?

Dave

11. Aug 9, 2013

### Naty1

There must be 'similarities' as both magnetic fields are plasma induced effects; there are likely differences as well since the plasma of the sun dwarfs our puny inner core of molten rock.

There is a lot of detail about the 'solar dynamo', the origin of the magnetic field of the sun, which is not understood. [check Wiki if interested.] The solar wind of our entire entire solar system varies with the magnetic field of the sun. That affects our outer atmosphere as in the aurora borealis for example which is a visual effect, and a number of solar scientists believe has climate effects as well.

Some solar scientists attribute current warming of numerous planets in our solar system to variations in the sun's activity...a lack of sunpots, as Davenn noted in a different context. The current very low level of sunspots suggests a cooler period should sunspot activity again increase as is expected. Last I read the activity level of the sun was NOT part of the UN IPCC [climate] reports. That is weird.

The earth's magnetic field seems to reverse every few hundred thousand years due to changes in the liquid inner core of the earth; the magnetic field of the sun seems to reverse at about 11 year intervals, but I don't know how really periodic [regular] either is. I'd guess those periods are related to the size, the mass, of the plasma origins.

[For some interesting contrasts between earth and sun cores, see here

http://en.wikipedia.org/wiki/Solar_core
and here

http://en.wikipedia.org/wiki/Inner_core] [Broken]

Last edited by a moderator: May 6, 2017
12. Aug 9, 2013

### Dotini

13. Aug 9, 2013

### jackmell

Alright, that wasn't bad but still no tamalie. Still, the dynamo theory remains intack from the thread I read above. That's where I wanted to start. Here are some quotes from Wikipedia:

Alright, "magnetohydrodynamic equations":

What in the system of magnetohydrodynamic equations uses to simulate the evolution of the earth or sun's magnetic field, what in those equations is responsible for field reversal?

Last edited: Aug 9, 2013
14. Aug 9, 2013

### Naty1

I'm guessing some aspect of chaos....randomness.....instabilities....etc...

no tamalie here either....will be tough to get a precise answer until someone who works in the field replies...
meantime, some things to get you started.....

Thought I'd skim 'MHD' in Wiki.....lots of pieces....INTERESTING.....seems like the answer is complicated:

ok, this seems to be along the lines I was guessing:

http://en.wikipedia.org/wiki/Plasma_stability

Last edited by a moderator: Aug 9, 2013
15. Aug 9, 2013

### jackmell

How about we look at the induction equation of MHD:

$$\frac{\partial B}{\partial t}=\eta \nabla^2 B+\nabla+(u \times B)$$

which I'll write as:

$$\frac{\partial B}{\partial t}=f(B,u)+\nabla+\eta \nabla^2 B$$

which is in some ways similar to a reaction-diffusion equation:

$$\frac{\partial B}{\partial t}=f(B,u)+\eta \nabla^2 B$$

We know reaction-diffusion equations exhibit pattern formation and oscillations such as the Turing stripes and dots of the Brusselator model.

And so I ask are the oscillating field reversals observed for earth and the sun caused by reaction-diffusion oscillations?

16. Aug 9, 2013

### davenn

there seems to be no regularity in the Earth's field reversals. Looking at the data shows it to be quite random with no preference for one polarity or the other. The shortest period seen was 2 flips within 50,000 yrs, the longest is ~ 35 million years

http://en.wikipedia.org/wiki/Geomagnetic_reversal

Solar magnetic field reversals on the otherhand are very regular. And in a couple of the papers that DH linked to described the process quite well. Here are the links DH posted in the other thread.....

Dave

17. Aug 10, 2013

### the_wolfman

The two important MHD equations are

momentum conservation:
$\rho \left(\frac {d\vec v}{dt} + \vec v \cdot \nabla \vec v\right) = -\nabla p + \vec J \times \vec B$

Faradays Law using an MHD Ohm's Law;

$\frac {d\vec B}{d t} = \nabla \times ( \vec v \times \vec B - \eta \vec J )$

To accurately understand the reversal process you need to consider both the evolution of the magnetic field and the evolution of the velocity field. However the MHD model does not accurately predict the time scale of the solar dynamo reversal. With a Spitzer resistivity it is simply to slow. We know that you need to include more physics ( electron inertia, electron pressure, the hall electric field, kinetic effects, etc) in the Ohm's law.

I'm not an expert on reaction-diffusion oscillations, but I suspect that the answer is no. In order to correctly model the field reversal, you need to account for the fact that changes in the magnetic field influence the flow via the Lorentz force.

18. Aug 11, 2013

### jackmell

Very nice start guys. I did look at the four references cited by Dave. Kinda' tough but an interesting concept.

I was mostly interested if the system of equations exhibit some sort of critical point, whereby if the state of the system were to pass through the point, a phase-transition would occur. An analogy would be pushing a glass of water across a table. While the glass is on the table, it's state varies continuously. However, at some point, when the glass is very close to the edge of the table, just a very small push, and the state of the glass of the water changes qualitatively as it tumbles off the table and crashes to the floor.

I was just curious if the equations modeling the field reversal of the sun exhibit a similar type of behavior, that is, during the evolution of the field, if it ever reaches some point, some critical distribution over the surface of the sun, then by virtue of the dynamics of the equations, the field (orientation) will qualitatively change state to the new orientation.

That is how reaction-diffusion works: if during the evolution of the system, it reaches a particular distribution (the details of which is not known), it will evolve into the distinctive patterns and oscillations.

Last edited: Aug 11, 2013
19. Aug 14, 2013

### BobG

It's not that good. It's mainly dead satellites (and other debris) that fall out of the sky. We put stuff up faster than it falls down, but a little cleaning every 11 years is a good thing. A little less stuff for the active satellites to run into.

It's too bad climate change can't be discussed. The absorbtion of heat by CO2 and the increase in CO2 means a little less "puffing up" of the atmosphere. The CO2 creates a barrier, keeping more heat inside and less heat escaping to the altitudes that low earth satellites orbit in, meaning long term atmospheric drag models should account for less atmospheric drag as time goes by.

In other words, in the future, the space debris we create will hang around longer before it finally falls out of the sky.

20. Aug 16, 2013

Reading the renewed "Voyager 1 has left the building" headlines that seem to be popping up from mainsteam science 'journalists' writing for popular, decidedly non-academic audiences on a seemingly monthly basis now got me to wondering...

While it seems a near certainty that the Voyager 1 spacecraft is still in our solar system, if at the extreme edge of it's magnetic/particle boundaries (if not it's gravitational edge, given the vast expanse of the Oort Cloud.) These premature announcements appear to be the result of impatient humans more than anything else, so ignoring whatever we call the place Voyager is presently speeding through... I was curious what, if any, impact this magnetic flip might have temporarily on the craft's observations and what effects the process of switching polarity might have in that region, at the edge of the heliosphere.

When this event happens, is there any possibility some consequential effects will be detectable by Voyager 1 instrumentation - the ratio of solar versus galactic particles, a temporary increase in high energy cosmic rays or in some other way? Or will it be a case of being so far out, with our solar system's magnetic field so expansive, that any brief hiccup during the flip gets ironed out by the immense size, distance and weakness of the field at Voyager 1's location?

I'm sure such a question only shows my lack of knowledge on the subject, but nonetheless it popped in my head and seems unlikely to be addressed in the media/elsewhere sans specific inquiry.

My reason for asking is simply in the hopes that we might be insanely lucky with the timing here - that Voyager is at the very edge of the magnetic field precisely at the once a decade flip, and so might be in a perfect position to capture some fascinating results at a stellar magnetic field's boundary during one of its polarity flips. Likewise, I expect this won't be the case, and for Voyager it'll be business as usual, but can only hope some exciting and unexpected results may come out of this fortuitous combination of events.