Timothy Birdnow

Timothy Birdnow

Anthony Watt`s website links to an Astronomical Society of Australia paper entitled “Does a Spin-Orbit Coupling Between the Sun and the Jovian Planets Govern the Solar Cycle?“ in which the authors claim:

“Based on our claim that changes in the Sun’s equatorial rotation rate are synchronized with changes in the Sun’s orbital motion about the barycentre, we propose that the mean period for the Sun’s meridional flow is set by a Synodic resonance between the flow period (~22.3 yr), the overall 178.7-yr repetition period for the solar orbital motion, and the 19.86-yr synodic period of Jupiter and Saturn.“

In other words, much like Dr. Theodor Landscheidt, the authors contend a correlation between the position of the planets-especially Jupiter and Saturn-and the internal activity of the Sun.

According to Ian Wilson, one of the authors of the paper:

“It supports the contention that the level of activity on the Sun will significantly diminish sometime in the next decade and remain low for about 20 - 30 years. On each occasion that the Sun has done this in the past the World’s mean temperature has dropped by ~ 1 - 2 C. “

This set off a series of comments at Wattsupwiththat, most arguing over whether gravity could have this kind of impact on the Sun.

Timothy Birdnow (08:31:09) :

I may be all wet here, but must this be strictly a gravitational/tidal matter? The Sun has a magnetic interchange with the planets, and wouldn`t this interchange (and the ionized plasma in the solar interior) be influenced by the position of some of the larger bodies in the solar system-especially Jupiter, with its strong magnetic field relative to the Barycenter and the Sun`s position.

I`m not a physicist, and may be completely out on a limb here.

anna v (09:40:31) :

This is from Wikipedia, not the ultimate truth, but I needed a quikc reference for the solar dynamo:

“The solar dynamo is the physical process that generates the Sun’s magnetic field. The Sun is permeated by an overall dipole magnetic field, as are many other celestial bodies such as the Earth. The dipole field is produced by a circular electric current flowing deep within the star, following Ampère’s law. The current is produced by shear (stretching of material) between different parts of the Sun that rotate at different rates, and the fact that the Sun itself is a very good electrical conductor (and therefore governed by the laws of magnetohydrodynamics).

Any electrically conducting fluid can form a dynamo simply by shear within the fluid itself, because of a consequence of Lenz’s law of induction: moving the fluid through a pre-existing magnetic field will induce electrical currents in the fluid that distort the pre-existing magnetic field. The direction of the distortion is such that the existing field lines tend to be dragged along with the fluid, like threads of dye embedded in taffy or syrup. If the flow has a strong shear component then the individual field lines are stretched by the flow, amplifying the existing magnetic field. Such systems are called MHD dynamos. Depending on the structure of the flow, the dynamo may be self-exciting and stable, self-exciting and chaotic, or decaying.

The Sun’s dynamo is self-exciting and chaotic: the direction of the field reverses itself about every 11 years, causing the sunspot cycle as ropes of magnetic field lines rise to the surface of the Sun and manifest as sunspots on the surface.

The detailed mechanism of the solar dynamo is not known and is the subject of current research.

It is obvious that what would be affected by gravitational tidal perturbations would be “shear within the fluid“, and that could change magnetic fields. A model is needed for this, and then, to have an effect on earth climate a mechanism of how magnetic fields operate on climate has to be found and proven.

So it is a long shot, that needs a lot of research.

Good.

Stevo (10:04:22) :

The point about the equivalence principle is right - the sun is not aware of its motion relative to the barycentre, it can only detect it through tides or other external effects. (It would be interesting for someone to plot tidal strength instead of barycentre motion to see if the correlation holds up. I’d guess it should.)

Some further things to think about. The sun rotates differentially every 25 days at the equator, ranging up to about 35 days at the poles. So tides will occur roughly every 25-35 days. The sun’s axis of rotation is tilted only about 7 degrees to the ecliptic, so there isn’t a great deal of asymmetry there. Jupiter on its own will simply give a 25 day tide, wherever it is in its orbit. That’s why the Jupiter-Saturn synodic period was proposed, the effect being similar to that of spring/neap tides. Although it should be noted Saturn causes only one tenth the tidal force of Earth or Mercury, which are themselves about half that of Venus or Jupiter.

The forces are undoubtedly small, so some sort of amplification process is needed. Since we’re talking about sunspots and the solar magnetic cycle, the logical place to look is the physics of the solar dynamo, which is currently not fully understood. The basic theory is that the differential rotation of the equator faster than the poles causes polar magnetic field lines to get wound up, which magnifies their strength. Loops bubble up and get twisted by Coriolis-induced cyclonic cells (sensitive to disturbances?), which introduces helicity, induces a current along the toroidal field lines, which restores a polar field to get twisted up again. The magnification is exponential, so this seems fertile ground for looking for small perturbations becoming large ones.

The other area to figure out is why the sun has a differential rotation. It can because it is a fluid, but what drives it to spin faster than the underlying core at the equator? The cycle period is driven by the meridional current: which rises at the equator, moves quickly to the poles in about 7 years, where it sinks and returns slowly to the equator over about 20 years. It is a wave of activity in this underlying current that carries the sunspots towards the equator - sunspots being loops of magnetic field that bubble up and pierce the surface. And the motion is known to be affected by the changes in the magnetic field, although it’s not known if it can be affected by changes external to the sun. All the mechanisms are linked. Figure out what drives the flow, and you may be some way towards understanding how planets could affect it.

You may find these documents relevant.

http://adsabs.harvard.edu/abs/1927PASP…39..228L
http://arxiv.org/PS_cache/astro-ph/pdf/0405/0405052v2.pdf

The second (big) one has a discussion of all the things that are not understood or don’t fit about the solar dynamo. Hope that helps.

Peter Taylor (10:25:20) :

I came across Landscheidt’s work several years ago - he had a remarkable capacity to predict both sunspot activity and El Nino - and this led me to review much of the oceanographic data indicating links to solar cycles - I am now convinced the solar wind affects cloud cover in pulses that somehow time the varying ocean cycles - ‘global warming’ (1980-2005) coincides with a triple peaking (harmonic) of the Atlantic 20yr cyle, Arctic 70 yr cycle and Pacific 30yr with the 1998 El Nino providing the record high - now all three cycles are entering negative phases and I expect the Arctic to begin refreezing this year or next - you can track all this my following ‘depth-average temperature’ data rather than surface data for the oceans. So the recent oceanic shifts would indicate a solar shift - with a time lag period (Landscheidt had also worked out the lime-lags) - and reflective-type cloud data points to 2001 as the crucial year (global thinning from 1983-2001, thicker since).

I could not, with my limited physics, understand how Landscheidt derived cycles of amplitude (which he equated with Gleissberg cycles of 70 years) from the spirograph patterns of the COM around the sun. But whatever the correlative method, which was obviously accurate, we need to have a more open mind about the mechanism - the movements of the COM may be correlated with more than gravitational tides or transfer of angular momentum - the solar system is a complex almost neuronal web of magnetic fields and channels along which plasma flows, is accelerated and constrained - and this plasma is electrical current, which in turn generates magnetic field . If I recall correctly, there is still no physics explanation for the accelerating solar wind - other than it being pinched by magnetic field lines - and it snakes around the solar equatorial belt and ecliptic in four massive spirals within the current sheet that occasionally align with the earth - solar storms move very quickly through these arms. What happens to the reverse current?
Or do we still have a model of a unipolar electric current that ends at the Heliopause and simply disappears? Hannes Alfven proposed that the photosphere could not reach its 3m degrees without the backcurrent. Did anyone ever answer that question satisfactorily? If he is right, then we may be looking in the wrong place for mechanisms - could not solar visible light variability, flares and sunspots be induced by electrical phenomena caused by the back-current (and this would be influenced by Jupiter’s field)?

And let’s not forget - there may also be galactic cycles influencing the sun - there are 5000 year peaks of varying amplitude in the berrylium-10 profiles.

Shouldn’t there be a major effort to integrate all this breaking science?

end comments

This from Tim:

I posed the same question at The Reference Frame, hoping to get Lubos Motl to weigh in. I received the following response:

“ Timothy Birdnow,

The sun is electrically conductive and quite immune to external electric fields. External magnetic fields are also negligible because they fall off as the cube of distance (there is no magnetic monopole).

Of course internally generated magnetic fields play a big role in the sun’s dynamics, but planetary effects can play a role only through tidal forces and that seems unlikely to me.
Gene Day | 06.29.08 - 7:23 pm “

I`m not a physicist, and I don`t even play one on t.v. I know about the inverse cube law, but I also know that it has been discovered by NASA`s THEMIS mission that the planets are connected to the Sun via “magnetic ropes“ which trigger explosive auroras. These Birkeland currents (named for Kristian Birkeland, who postulated that solar electric currents powered the auroras-something proven in the 1970`s) are truly amazing. According to NASA investigator Dave Sibeck states: “It was very large, about as wide as Earth, and located approximately 40,000 miles above Earth’s surface in a region called the magnetosphere.”

Here is more on Birkeland Currents.

At any rate, this is not just a matter of two magnetic fields acting on one another; there is an interaction between the Sun and planets, and, the Sun`s own magnetic field may be pushing against Jupiter and the other planets. I don`t know. Is Gene Day correct? I suspect that these magnetic ropes influence the Earth`s climate, but do they have a cumulative influence on the Sun?

Any physicists want to weigh in?

Related to this, Dr. Manuel Oliver from the University of Missouri, Columbia (Mizzou) has argued that we grossly misunderstand the nature of the solar interior, and that gravitational interaction with the planets does indeed effect the Sun`s behavior-and the Earth`s climate.

I don`t know if this is true, but it makes for some interesting speculation.