Michael C., the influence of the Sun's field to that of the Earth has been discussed earlier in this forum, and the effect is practically negligible. In fact, the Sun's field does not penetrate Earth's at all, but the plasma current from the Sun is deflected by Earth's field. We are in grave danger when Earth's field eventually changes its direction in the future.

Another fact is that the Sun's magnetic field changes direction about every 11 years, and this has very little practical effect: http://www.dailygalaxy.com/my_weblog/2012/04/the-great-switch-suns-magnetic-field-does-a-complete-reverse-every-11-years.html.

You should not post nonsense here, when facts can be trivially checked from Wiki or other sources: http://en.wikipedia.org/wiki/Earth's_magnetic_field.

Neutron's magnetic moment is caused by the quarks it comprises.

Don't ask me where quarks get their magnetic moment..:-).

http://en.wikipedia.org/wiki/Earth. The Earth constantly dissipates gravitational and rotational energy by internal rotation of the core. To create Earth's magnetic field you need moving charges, i.e. a current, so the magnetic field here is induced by non-equilibrium conditions. This is also pretty evident if you consider the fact that Earth's magnetic field keeps on changing over time and even reversing its direction!

Due to the iron inside the earth.

@Nainan. It does not have anything to do with water. Your argument is unphysical and wrong.

@Graham. You're exactly right. Not only do the continents (platelets) move, but Earth's magnetic field changes slowly with the changing mass currents and will (again) reverse itself in the future. This has no correlation with "water" or anything else on the surface.

@William, there's a famous example of statistical correlations: There's a strong correlation between consumption of ice cream and drowning incidents. Thus, eating ice cream is extremely dangerous.

Can you provide a link to a published scientific paper on the claims in your link?

New study on Earth's magnetic field: Field direction related to growth of solid core!

"A study that used numerical modeling discovered a link between Earth's magnetic field reversal and the unbalanced growth of its solid inner core. Researchers Peter Olson and Renaud Deguen of Johns Hopkins University detected that the axis of the magnetic field is in the growing part of the core. The next pole reversal may be under way, which could threaten global power grids and communication systems."

http://www.newscientist.com/article/dn22059-growth-of-earths-core-may-hint-at-magnetic-reversal.html

One possible explanation for the reversal is given here: Plasma Physics: An Introduction to Laboratory, Space, and Fusion Plasmas by Alexander Piel.

The author claims that the reversal may be caused by diffusion of the magnetic field through the core of the earth (this phenomenon is well known in plasma physics where a conducting fluid can diffuse across a magnetic field and vice versa). A rough calculation of the diffusion time of the earth's B-field across the core yields a diffusion time of about 10k years which matches the order of magnitude of the reversals.

However I have some doubts because if diffusion would be the cause then the reversal should happen gradually and to my understanding the changes in the B-field start quite slowly but in the end the major part of the reversal happens very fast which would contradict such a diffusion-theory.

Does anyone have some opinion about this explanation?

I'm not an expert on plasmas but I am an expert on diffusion. I think your last statement correctly points out the problem with the diffusion theory - the distance always grows proportional to the square root of time, if the diffusion coefficient is time-independent. Thus it's difficult to see how the diffusion argument would explain the reversal.

I embarassed to admit that my understanding of the Earth's magnetic field and the apparently-random reversal of the field is perhaps too simplistic. But I like it, at least it lets me sleep at night. The geomagnetic reversal seems to be not periodic enough, at least as measured by basalt domain orientations. That's the rub.

But we reasonably theroize that the Earth's subcores are spherically layered, like an onion and that this is where the magnetic field originates. And we know that the closer to the center the more dense the materials. We also know that the Earth has slightly variable angular acceleration which has a varying effect through the layers depending on their mass density, which itself is slightly variable (with decreasing effect from the surface to the core) as the upper surfaces continuously reorient themselves.

So we're left with our layers slightly changing their relationship to each other, with Maxwell's Laws (into the magnetic induction equation) describing our geodynamo that creates the magnetic field in the first place.

So (and this is how I now sleep at night after wondering about the reversals for too long) the varying relationship between the layers leads to our constant wandering of B-field, but the nature of these surface effects "hunting" their lowest potential to each other (each producing their own component of goemagnetic field) leads to random reversals such as we would find in any typical many-body problem.

In other words, I envision it like a room full of politicians spouting out a nonstop parade of "yeas" and "nays" over a certain question ... there will be a narrow consensus of either "yea" or "nay" over a few days, but as the politicians interact with each other in their own many-body arrangement, eventually the consensus will narrowly flip from "yea" to "nay" or vice-versa.

The lamina of the outer core all add their own component of geomagnetism, all somewhat randomly, but the consensus at any given time allows for the slight wandering and ocassionally flips of orientation.

William, I have a question to your post: You wrote "the implication of this idea is to the effect that the Earth's magnetic field does not originate within the core of an isolated Earth, but with an interaction between Earth fields and the field of the Sun..."

Unfortunately I cannot open the paper, but if the B-field of the earth is not created in the core of the earth, where does it come from (there still has to be an earth field which interacts with the sun according to the theory you mentioned) - how is this one then created?

William,

This is a nice thought experiment, but why not calculate it?

I fail however to see, how you get a frequency of the B-field of 25 kHz - the period of the suns B-field is ~22 years (i.e. the change of the direction of the field vector).

As the plasma density between earth and sun is rather thin, I guess you can neglect plasma effects for a first estimation.

I'm afraid it doesn't look so good for this idea, according to my following (rough) estimation:

If you want induction, you have to have an alternating B-field, so you have to work with the alternating B-field, that is given by the sun. This has, as I mentioned before a period T = 22 years --> f = 4 x 10^(-12) Hz.

from that you can calculate the wavelength L via: c = L * f, which gives:

L = 0.75 x 10^20 m

As the B-field of the earth is a dipole, the resonance condition is that the dipole lengh (so the diameter in this case) has to be L/2

For our case that would be ~ 0.4 x 10^20 meters.

Than I substracted the diameter of the earth itself to see how far the resonant dipole field would go: 0.4 x 10^20 m - 1.27 x 10^6 m = 3.9 x 10^19 m

Divide this by two (because yo have a sheath around a sphere: ~2 x 10^19 m = 2 x 10^16 km (that you then roughly be the thickness of your resonant field).

As the distance between earth and sun is only 150 x 10^6 km = 1.5 x 10^8 km your pickup-dipole for the magnetic induction from sun to earth would have to be more then 10^8 times the distance between earh and sun (if I haven't overlooked someting important).

Hi Vasuki:

Virtually all geophysicists agree that the magnetic field of Earth originates in the motion of the metallic liquid outer core (between 2890 km and 5150 km depth). I appended a brief introduction to this topic from Don Anderson's book on Earth. The book was written about 30 years ago and much more reasearch on this topic has happened since. However, it is clear that motion of the metallic liquid outer core is the only viable theory to explain Earth's magnetic field.

The details of the fluid motion determine the direction of the magnetic dipole axis (magnetic North and South pole) which has been moving over Earth's surface with time. As shown in the paleo-magnetic record relatively sudden and large motions alternated with periods of almost stability.

A electrically conducting liquid, such as the molten outer core of Earth, which is exposed to thermal gradients as they persist in Earth's interior will convect and thereby create a magnetic field. The mathematical description of this process is in terms of non-linear partial differential equations. Chaotic behavior of the magnetic field magnitude and direction are quite common for such systems.

Planets that do not possess a electrically conducting liquid region in their interiors do not have magnetic fields, for example Mars and Venus in our solar system.

Wolfgang is absolutely right. I think it's clear that the numbers just don't work out for the alternate scenarios - especially the Sun cannot possibly induce such permanent fields. I can easily come up with a few more general arguments:

(i) It's well established that Earth's core works like a dynamo; moving charges (conductors) always generate a magnetic field.

(ii) Some other planets farther from the Sun actually have much stronger B-fields than the Earth, while Venus has virtually no B-field (see e.g. http://www.astronomynotes.com/solarsys/plantblb.htm). If Sun induced the fields of planets, the B-fields should rapidly decay in magnitude with distance from the Sun.

(iii) If the Sun induced the B-field of the Earth, the field should be changing with distance (seasons) and the Sun's fluctuating particle flux.

(iv) I cannot see how one can explain the reversals coming from the Sun.

I think there's as much credibility to claim that Earth's B-field is externally generated by the Sun as there is to claim that the Earth is flat :).

There's no doubt that the solar magnetic field interacts with ours, but usually the effect is relatively small (at least on the ground level :)). Are you aware of the fact that the Sun's B-field actually changes direction every 22 years? If Earth's field were Sun-generated, this should have a significant effect on Earth.

Graham, thanks for your post. Can I give you a friendly advice to get your views understood: punctuation.

The source of the earth's magnetic field is the electric current circulating deep in the interior of the earth.

It is in variable nature due the following 3 components:-

(1) Declination angle

(2) Inclination or angle of dip

(3) Horizontal component of earth's magnetic field

At particular place these components / elements are different due flat shape of earth.

There are new data that explain the details of Earth's self-generated magnetic field even better than before: http://www.ouramazingplanet.com/4407-earth-core-hotter.html

Tapio, this is a very interesting and fascinating question. As far as I know, the reason is not yet established although there are plenty of speculations. Generally it is believed that it is the dynamo mechanism, but how does it work and what defines the value and the direction of the field is still not known.

Dear Michel, can you explain in more detail what is the main issue that remains unresolved? I'm not an expert in geophysics (I'm a condensed matter theorist) but I can figure out that a large T gradient is needed to drive the dynamo effect. The new experiments seem to confirm this.

Tapio, the dynamo effect is an extraordinary phenomenon. You have some conductors moving with respect to others with an electrical contact between them. It is quite possible, that the movement does not produce any electrical currents, and hence no magnetic field. But under certain conditions there may be an instability: a small fluctuation of current will create a magnetic field which in turn will produce a greater current in the moving parts. As always, there is an instability threshold, meaning that the motion must be fast enough to make the dynamo work. So, the problem is to find such an instability inside the Earth. The problem is difficult because of the Cowling theorem:

dynamo is not possible if the problem possesses spherical or cylindrical symmetry!

But the general, non-symmetric case is hardly tractable mathematically, besides the exact nature of motions of the liquid inside the Earth is not known. So, here you are...

If you think about the Earth and the Sun's Magnetic fields together where the

Earth passes through the magnetic field of the Sun, the Sun will impart a torque

upon the core of the Earth ( an electro-motive force ).

Changes in the Sun's electro-magnetic field intensity will impart changes in the

applied torque applied to the core of the Earth. That applied torque

increases and decreases, and the Earth's rotation rate about its own spin axis

will also increase and/ or decrease due to the increase and/or decrease in the applied Solar electro-magnetic torque.

The direction and intensity of the Earth's magnetic field is thus a record of the

Earth's response to the changes in the Sun's Magnetic field strength.

An analogy would be an electric car that uses energy to go uphill, and then

recharges the battery ( regenerative braking ) when it goes down hill.

A better analogy is that the Earth is a giant flywheel that is spinning such that

part of the time the earth is resisting the Sun's efforts to increase the earth's spin rate,

and part of the time the Earth is resisting a deceleration in its spin rate.

In either case the Earth will be producing a magnetic field, but the polarity of the

field and the intensity of the field varies according to the intensity of the change

in the magnetic field strength of the Sun.

There are a couple of on-going experiments to verify the dynamo effect in Earth, other planets, and stars, magnetars, and galaxies.

http://complex.umd.edu/research/MHD_dynamos/3m.php

http://plasma.physics.wisc.edu/mde

Tapio shared a great link too!

Michael ... regarding this Earth-Sun dynamo theory, I have a question ... since the Sun's magnetic field can do no work on the Earth, and there is a change of angular acceleration with the applied torque, thus necessating a change in Force, what is doing work on the system? If I hold a compass and the needle against the Earth's magnetic field, then my muscles are supplying the work necessary to raise the potential of the needle against the B-field until it swings around again. What does that for the Earth-Sun system?

Wouldn't that necessitate that the Earth's moment of inertia would have to change with the interaction of the Sun's B-field? And if so, what supplies the work necessary to adjust the moment?

I must be missing something here, I'm having a hard time envisioning this process.

Michael C., the influence of the Sun's field to that of the Earth has been discussed earlier in this forum, and the effect is practically negligible. In fact, the Sun's field does not penetrate Earth's at all, but the plasma current from the Sun is deflected by Earth's field. We are in grave danger when Earth's field eventually changes its direction in the future.

Another fact is that the Sun's magnetic field changes direction about every 11 years, and this has very little practical effect: http://www.dailygalaxy.com/my_weblog/2012/04/the-great-switch-suns-magnetic-field-does-a-complete-reverse-every-11-years.html.

You should not post nonsense here, when facts can be trivially checked from Wiki or other sources: http://en.wikipedia.org/wiki/Earth's_magnetic_field.

The Applied torque may not need to be as high as one might think because the

Sun literally took hundreds of millions of years of applying torque to the inner core

of the Earth to accelerate ( or prevent the deceleration of ) the rotation rate of the Earth.

The inner core of the Earth makes one additional rotation inside the Earth

every 400 years. That is the outer surface of the planet makes 365.26 x 400

rotations while the core makes 365.26 x 400 plus 1 rotations.

The torque is therefor applied to the inner core, and the outer core is a

liquid ( or plastic ) transfer fluid that transfers torque from the inner core

to the mantle.

Such a slow rate of transfer would imply a laminar flow of viscous

liquids rather than a turbulent flow. The change is only approximately

55 arc minutes of differential spin rate per year ( currently )

A picture of the results of the applied torque can be viewed on the cover

of Scientific American Magazine March 2000 Issue. it is shown as temperature

differences, but I recognized it as internal differences in motion.

This would be layered laminar flow ( westward creep of the mantle).

The strange part of this is that the Earth's orbit about the Sun means that the

Earth passes thru the Sun magnetic field, and the Sun's magnetic field is stronger

on the Sunny side, and weaker on the night side simply because of the

difference in distances at the point of application. The applied force is

greater on the nearer - sunny side, and lesser on the farther - night side.

What is strange is that the gravitational force applied by the Sun accelerates planets into orbital motions that cut through the Sun's Magnetic Field Lines.

What sets the Earth apart is the size of its iron-nickel core, and the

laminar Flow of the outer core that creates a protective Magnetic envelope.

The real question is what were the changes that occurred starting around

630 million years ago that warmed up the planet, and changed conditions such

that life could evolve to greater sizes, occupy the oceans, and later occupy the

surface of the Planet without getting extinguished by powerful bursts of

energy from the Sun?

There have been hundreds of geomagnetic reversals especially in the last

252 million years and only a few major extinction events in the

last 542 million years. Most of those can be traced to major impact events,

or the sudden drops in ocean levels of up to 80 meters.

I suspect the outer core is always in motion even when there is little differential

motion between the inner core and the lower mantle. There should still be

Coriolis motions of the fluids of the outer core.

Michael C. -- I have to say, it is still a lot around which to wrap my head, but you've explained the theory clearly. What measurements have been made to confirm the diferential rotational velocity of the inner core relative to the rest of the Earth?

Your point about the field strength difference from sunny to shady is interesting, even if 100% of the sun's magnetic field were blocked from the Earth's core as Tapio suggests, there could potentially still be some crustal magnetic variation from the sun due to the seasonal temperature fluctution which could produce a Seebeck gradient. This has been used to explain the the striation orientation of ice chunks in orbit around Saturn.

Seismic waves passing thru the Earth arrive at receivers just ahead or just behind

the time they are supposed to reach the receiver for the waves that refract and reflect

off the interface where densities change.

It has to do with S waves and P waves and their arrival times and the differences

of the arrival times fron different paths, and different stations.

I do not remember all the details, but atomic clocks come into play as the

time differentials are small.

Dear Graham, I don't fully understand your question, but atomic nuclei with many protons and neutrons are actually highly aspherical.

Graham, a simple explanation can be found here (as usual): http://en.wikipedia.org/wiki/Atomic_nucleus.

Atomic/elementary particle level physics is controlled by quantum mechanics, while the planetary core dynamics by classical physics. They have virtually nothing in common.

Any classical system can be explained quantumly, albeit with great difficulty. Of course on our time-scale, planetary geodynamics is a classical system and we don't observe quantum effects. But on a geologic time scale, perhaps the probabilities of the quanta including tunneling through unlikely probabilities could help us model some of these anomalies. The geomagnetic flip in particular is still not modeled, and it appears chaotic. That seems to have at least a vague property of a quantum system.

However I do not volunteer to model the geomagnetic flips in this way because it seems a lifetime of work! Is it an ideal system to model something on the geologic scale? Probably not. But will it at least give us some new insights of something that has us stumped?

Graham -- I don't know of a decent model that shows periodicity for the geomagnetic polarity flips. It is apparently chaotic when charted to the basaltic data we have. However, I've been out of this area for a while, so there may be something new.

Joseph, I don't know that relation, do you mind listing what the variables q, p, f, b, a, G, e represent and from what the relation is derived?

Dear joseph, i am agreed with your opinion

Hi Joseph, I would love the symbol definitions ... I guess the take is that if a meteor of large enough impact force hits the Earth then there is a spring-like action, i.e. some oscillations in an LC-like circuit? I may not have this right, I'm just guessing at this point, having just been introduced to your theory.

Is there evidence to support this? For instance some periodic meteor impact evidence that corresponds with the periodicity of geomagnetic pole flips as seen in basaltic signatures?

Geomagnetic data show no correlation with Earth's dipole reversals and asteroid impacts. The liquid core dynamics or response has nothing to do with harmonic springs.

Hi Tapio, Considering we still have no demonstrable model of the geomagnetic pole flips, I'm interested in any theory. All we can conclude now is that they're chaotic. I'm okay with concluding it's a system that defies prediction, but given all of the measured data we have on the flips, it would be terrific to at least have a theory.

Also, I have a question about what you wrote above, that "geomagetic data show no correlation with Earth's dipole reversals." I believe the historic geomagentic data we have (i.e. basaltic evidence) IS the measurement of the Earth's dipole reversals.

Until shown otherwise, I'll have to go sleep at night with my messy understanding of a laminar many-body problem with spherical symmetry. But that's hand-waving, I haven't been able to actually create any kind of model with that.

Graham, thank you for those articles, I enjoyed reading them.

There may be some mistakes in both of those articles ... In the NASA article, the author writes "while Earth's magnetic field can indeed weaken and strengthen over time, there is no indication that it has ever disappeared completely." I agree that there is going to be residual permanent magnetism, but if the polarity of the electromagnetic field flips, it will necessitate at least some duration of measurably negligible field, because the cross-product of the Lorentz force demands that.

On the Insider article, the author writes that NO (and presumably NOx) consume (presumably stratospheric) ozone. This is a simple enough reaction, but we also know that in the trosposphere, NOx and VOCs combine through photochemical reactions to form new O3 through the Leighton cycle. I'm not sure about concluding the O3 balance without a more complete model.

Can we all agree on this question that there is no experimentally-verified theory as to the process of pole flips?

You might also look at the Mars Magnetic field that NASA Published.

I have wondered if magnetic fields are more complex than we usually

imagine, and if planet size is important, and if having a Moon is important

to keep the interior of a planet stirred up.

It would seem to me that internal differential motions ( fluid or plastic flow )

is very important in creating and maintaining a protective magnetic shield.

Large Life forms on or near the surface of the Planet for about 630 million years

of the 4567 million years, and of that 630 million years, only the last 420

million years have seen large life forms on land.

Planets out-gas and out-water, but keeping the water and the gas on or near

the planets surface ( not losing it to space ) is an important job of a protective

magnetic shield.

It all begs the question " What changed internally or externally to

allow Earth to maintain a protective magnetic shield for the last roughly

10% of its existence ?", which also allowed Earth to maintain a larger

life form evolutionary process which began around 630 million years ago

under the oceans.

I suspect that planets undergo slow evolutionary processes of growth and

internal redistribution of materials that may, or may not ,lead to

allowing that planet to have surface life for a limited period of time.

We are in the midst of the sixth major extinction event, and there were numerous minor extinction events. I doubt that magnetic pole wandering and

magnetic reversals had much to do with any of extinctions unless they can

be related to any of the forms of climate change such as sudden drops

in sea level, or flood volcanism, or enormous space rock impacts.

In short quick changes lead to extinctions, but slow changes lead to

migrations of plants and animals. It would seem that magnetic reversals

would fall in the slow change category.

More food for thought. The Earth is a complex four dimensional

puzzle of fast and slow changes. Magnetic reversals are a tiny part

of that puzzle.

Michael, first of all I said that the geomagnetic data do not show any correlation with asteroid impacts. Of course it shows exactly when the field was reversed. Second, chaotic behavior naturally emerges from non-linear hydrodynamics & magnetohydrodynamics.

I have found a very useful tool to helping solve mysteries to be a wall chart called

A CORRELATED HISTORY OF THE EARTH. It can be ordered on line for

about $ 20 to $25 US Currency.

The geomagnetic reversals are recorded on this chart along with numerous

other things like average temperatures, Oxygen content, CO2, geologic eras,

impact craters ( sizes and locations and periodicity ), volcanic activity, animal and plant types, and when they began, etc.

Since the record of geomagnetic reversals is recorded in the ocean floors,

the record only extends back to about 252 million years. This doesn't mean

it began 252 million years ago, it is just that the ocean floors began forming

at or before 252 million years ago so that is when the record starts.

I keep two of these charts on the wall behind my computer screen at work,

mostly because I can't read the fine print if it is too far away.

Several of the geologic eras begin and or end with either impact craters,

or flood volcanism, or the sudden end of reefs when ocean levels drop

several 10's of meters ( End Permian Extinction ).

Since there are many more reversals than geologic eras, and there is

no obvious periodicity in the reversals, they may or may not be related

to giant impact events, or possibly only a few reversals are related (directly

or indirectly) to giant impact events. If they are related, I would expect a

long time delay between an impact event, its fracturing the surface of the

planet, and internal changes in stress relief, and redistribution of

materials inside the planet, and changes in the planets rotation rate that

would show up eventually as a magnetic reversal.

Of course very long term changes in the Field strength of the Sun could

also impart changes in the field strength and polarity of the Earth.

Short term changes like the 11 years sunspot cycles would have only

minor effects.

Geomagnetic pole reversal will not cause (great) danger to nothing. If so, then life on Earth would have been erased or at least drastically changed every time this happens - each 250 thousand years, give or take. The link posted by Graham Burnett gives fair explanation, that is:

http://www.nasa.gov/topics/earth/features/2012-poleReversal.html

Information being copied from the Wiki sites are mostly inaccurate, since anyone can modify anything in them. It would be a total nonsense to use wiki sites as references. I believe this is not a professional method, rather, it is of a beginner's.

The NASA Flux Transfer Events is exactly what was needed to confirm that Planets grow larger with time. Tons of material enter the Earth Every 8 minutes when the

Magnetic Portals open and close.

The question would then be, " How many Tons " every 8 minutes?

What is the annual rate of mass gain?

What is the rate of increase in the radius of the Earth?

How do the rates change with increases and decreases in the

Earth's MagneticField strength?

Michael Clark ... do we know that there is an annual rate of mass gain and an increase in the radius of the Earth? Have there been any tests or models or papers on this?

I ask because mass also escapes the Earth with light-element gases.

I know that Los Alamos Laboratory has listened to the sound of incoming

meteorite as the crackel, pop, hiss, and burn up, but i came up with another way

to calculate the mass gain.

I used the recession rate of the moon away from the earth moon Barycenter

to calculate the mass gain of the Earth required to accelerate the Moon to

a higher orbit, and simultaneously decelerate the Earth to a lower

orbit, and increase the absolute value of the distance between the two

Spheres.

In its simplified form the mass gain is roughly one part in two times the

elapsed time in billion s of years.

The mass is 5.97352 E 24 divided by two times the elapsed time which is

2 x 4544.40 +/- E6 Years which is 6.5724 E 14 Kg of new mass to

raise the Moon, and another 6.5724 E 14 Kg to lower the Earth orbit.

The combined net change in the distance is about 41.78 mm, while

the actual net surface to surface change is only 38.2 mm.

The combined Earth and Moon increase in radius is 3.58 mm.

This is close to the GPS average annual recalibration of 4.15 mm per year.

The added mass should only account for about 2 mm of dust added per year,

but the Earth swelling averages about 4.15 mm per year.

There are too many things changing simultaneously to really pin it down, and the

location of measurement using lasers is also subject to local changes in

the Planets radius under the observatory.

Only locations with old Lawns seem to keep the acquired dust such that the

lawns grow deeper by about 1 inch every 25 years. All the rest tends to

end up at the bottom of the oceans.

1.3 E 15 Kg of mass gain is about right.

There is also a guy in Italy or Greece the came up with the same mass gain

by applying an equivalent single magnitude Earth quake 9.6 to determine

the required energy release and the required mass gain to create that energy release.

It does seem clear that the generation of the magnetic field is linked to the rotation of the earth, since Venus with a similar iron-core composition but a 243 Earth-day rotation period does not have a measurable magnetic field. It certainly seems plausible that it depends upon the rotation of the fluid metallic iron which makes up a large portion of the interior, and the rotating conductor model leads to the term "dynamo effect" or "geodynamo", evoking the image of an electric generator.

Convection drives the outer-core fluid and it circulates relative to the earth. This means the electrically conducting material moves relative to the earth's magnetic field. If it can obtain a charge by some interaction like friction between layers, an effective current loop could be produced. The magnetic field of a current loop could sustain the magnetic dipole type magnetic field of the earth. Large-scale computer models are approaching a realistic simulation of such a geodynamo.

I have wondered if the dust particles found on parked cars when the snows melt

was related to a supply of cosmic dust, or is it just dust from winds carried from

desert regions to other areas of the globe.

The desert dust seems to currently be particularly bad from the Gobi Desert,

the Sahara Desert, and even Phoenix Arizona has had some bad dust storms.

The problem the becomes what proportion is just moving dust from one location

to another, what comes from volcanoes, and what proportion comes from

outer space?

The much simpler solution ( or so I originally thought ) was to employ a simplified

concept of orbital motions of a co-linear paired system of " planets ".

The original concept is that if there is no change in the average distance

between centers of planets, then there is no change in forces, thus no

change in gravities, and also no change in mass, and no change in mass ratios,

and orbital distance ratios.

This did not turn out to be the case for the Earth and the Moon as the

absolute value of the distance between the two " planets" is increasing.

The distance is increasing by the increase in the time it takes for a Laser

beam fired from the Earth's surface to reflect off the corner reflector on the

surface of the moon and return to the source on the earth by a few nano-

seconds per year.

Not only is the mass of the two partners changing, but the mass ratio

of the two partners is changing. Also we are not observing the

change, but observing the combined results of the rate of change in

the mass of the two partners.

The rate of change of each partner can be assumed to be quite small

because the elapsed time in billions of Years is quite large

Some where between 4.536 billion years and 4.567 billion years.

The uncertainty come in that the laser measures the surface to surface

rate of change in the distance, not the center of mass to center of mass

rate of change in the distance.

Another problem is that the two partners do not grow at the same rate

because the Earth has over 81.3 times the mass of the Moon, a significantly

larger radius, surface area, volume, and ability to attract foreign objects

to gain additional mass.

In short the bigger planet always grows faster than the smaller planet.

To shorten this explanation up, The Earth moves toward the Barycenter

by about 0.5 mm per year, and the Moon moves away from the Barycenter

by about 42.3 mm per year, so the net change is only about 41.8 mm per year.

The change in the mass of the Earth overwhelms the change in the

mass of the Moon, which really helps simplify the calculation to

both changes being predominately created by a change in the mass of the

Earth. Each change requires an Earth mass change of 6.5 E 14 KG,

so 2 x 6.5 E 14 Kg = 1.3 E 15 KG.

The change in the mass of the Moon should be a very small fraction of

one percent of the Annual Earth Mass change, so it is not significant

enough to be considered in a short term calculation.

Notice here that the sloshing of the tides and the expansion of the Universe

are not even considered as viable participants it the process of distance

change between a co-linear, co-orbiting pair of " planets ". Only the

rate of change in the mass ratios is considered.

I think that the solar protuberances are the cause of Earth's magnetic field. At least, such an assumption is in the context of our (together with Elena Kadyshevich) PFO-CFO hypothesis of the Solar System Formation and of the hypothesis of the Sun-like stars transformations (the corresponding papers are available at the ResearchGate).

William, according to our best understanding the field reversal is chaotic (non-periodic) because it's induced by a nonlinear process (the flow fields inside Earth).

Apparently, it is difficult to search the Earth's cause of the Earth's magnetic field variations. Therefore, there are ground to think that this cause is out of the Earth. If this is so, the possible cause of this variations lies in the changes of the solar activity, that reveals itself in the variations of the solar wind which, in its turn, is determined by the power and unpredictable moving of the fields of protuberance activity at the Sun.

The change in the strength of the Magnetic field of the Sun in conjunction with the

internal and external changes within the Earth should be reflected in the rotation

rate of the Earth, and specifically the number of Lunar Cycles ( number of days )

per year. If the spin rate is faster, the number of hours per day will go down while the

numbers of days per Lunar cycle will go up, and the number of days per year will

also go up.

I understand that there were more than 400 days per year previously and

now we are down to 365.26 days per year., and it has not been a smooth

transition, but has reversed direction at least once.