Pole Switching

[StarLab]

Since suntrack is asking about global warming, I would like to query about the poles switching, the timing and its implications, and any impending switches that might occur soon and what they mean. I'm not sure Pole Switching has been mentioned much on this forum, so I've decided to bring it out right now. Should become a nice, steaming hot topic like grandma used to make.
So, dish out those articles, share your opinions, and let's have a pole-switching discussion! Woo-hoo! B)

[Duane]

There is some evidence that the pole is in the process of switching right now. Anomalies hint at magnetic pole flip . The last recorded filp (recorded in ocean rocks) occurred about 780,000 years ago.

Alot of woo-woos believe the flip will result is some sort of catastrophe, although there is no evidence that past flips caused anything like that, and there are several such flips recorded in the magma making up the ocean floor.

Could it be happening? Maybe. The north magnetic pole has been seen to be moving approximately northwesterly at some 10 to 40KM per year--faster lately. Earth's Inconstant Magnetic Field. Reviewing the history of such flips in the oceans rocks, it is seen to flip every 300,000 years on average. Maybe we are overdue for one?

Further the strength of Earth's magnetic field has been declining by some 10 to 15% over the past century or so.

Much like the Sun's magnetic field, we don't have a good understanding of what causes Earth's magnetic field, making it hard to predict what may or may not be happening. While it is generally agreed that the magnetic field has something to do with the Earth's molten iron core, the actual process causing the magnetic field has not been clearly identified.

[StarLab]

"The actual process," I believe, is simply the earth rotating on its axis. You see, this causes the heavier stuff to fall into the center of the earth, and since the earth rotates on its axis, the heavy molten iron generates a magnetic field as a result. Since either end of the poles have a charge, the rest of the magnetosphere surrounding the earth is neutrally charged, effectively deflecting oncoming solar particles, as most of the neutrons tend to stay in the Sun's core (in agreement with the Iron Sun theory).

[Duane]

"The actual process," I believe, is simply the earth rotating on its axis.

The Earth's rotation may play a role, but it is not the process. Differential rotaion of the Earth's core versus its mantle may also be part of the process. Rotating molten iron, on its own, does not lead to a magnetic field.

From Wikapidea:

Dynamo theory proposes a mechanism by which a celestial body such as the earth generates a magnetic field. In the case of the earth the magnetic field is believed to be caused by the convection of molten iron and nickel, within the planetary core, along with the overall planetary rotation. This results in the creation of electric currents as well as a magnetic field. Similar magnetic fields are present in many celestial bodies including most stars such as the sun and active galactic nuclei.

This is one possible explanation, however as I said the actual process which forms the magnetic field is not well understood.

The Earths magnetic field is not neutral, it is bi-polar. Thats why we have north and south magnetic poles.

[StarLab]

But they must get close to cancelling each other's charges out at or near the earth's equatorial axis/circumference, and since charged particles are sent towards us, they must be deflected by the near neutrality, and those deflected particles thus go around the earth, and some go around the poles yet are oppositely charged and are thus attracted to the poles, which is why the poles are the weakest point in the magnetic field (or am I wrong and they're the strongest point?).

[Duane]

No, they are the weakest point. The bi-polar magnetosphere deflects stongest at the equator, where the field is the strongest. Most solar particles are carried past the earth with the solar wind, and only a small percentage get caught up in the magnetic field to trail back to the poles.

These are also the cause of the Van Allen belts--zones of radiation trapped in the magnetosphere.

[spacepunk]

Since suntrack is asking about global warming, I would like to query about the poles switching, the timing and its implications, and any impending switches that might occur soon and what they mean.

When the poles switch, then in theory anyway the Van Allen belts disapear. The Earth then gets all kinds of solar radiation particles raining down on its surface that otherwise would be colliding with Earth's magnetic field and viewed as aurora. This would lead one to search for life extinction evidence in the stratiographic history, or mutation/proliferation of new kinds of life forms. I don't know if there is any documentation of either, or global warming, but there is ample evidence of pole switching.

[StarLab]

On a regular basis?

[GOURDHEAD]

Is there any evidence for non-nutational changes in direction of the spin axis of the earth being coupled to the changes in the location of the magnetic axis? One can imagine thermodynamical randomness causing variations in densities of the liquid iron/nickel core which would apply a precessional force to the spin process. To be catastrophe avoiding the presession would have to be very slow. If it should change the alignment of the spin axis such that it lies close to the plane of the earth's revolution about the sun, significant climatic changes should be expected.

How are changes in magnetic field strengths and orientation as recorded in rocks distinguishable between plate tectonics effects and those of magnetic pole migration?

[Matthew]

If the magnetic field flips we will be open to moe solar radiation than usual, much more. If it will be a fatal dosage even the best minds are unsure. But I don't really want to find out.

But the "flip" is not an insteneous thing. It happes in the course of a couple of years, nearly a decade. Which of course is essentially an instant in geological terms.

[unregistered]

Here's a related news item from last year and the discussion at Universe Today, about the Sun's pole switching. This may help in the understanding of Earth's pole switching, effects, etc

http://www.esa.int/export/esaCP/SEMDU4ZO4H...HD_index_0.html

http://www.universetoday.com/forum/index.p...ct=ST&f=2&t=521

[Whim]

Reading the forum so far has me confused. First, magnetic poles do not cancel each other out. The strongest effects from a bipolar magnet are at it's poles, not at the center of the field. The magnetic "lines of force", or "flux", are directional, going from north seeking to south seeking poles. This is why the Auroras are different at the north and south poles. The process by which auroras are created, is the captured charged particles spin around the flux lines (magnetic field) going towards the poles. The direction of their spin and the pole they are directed towards is determined by their electrical charge. (Their spinning motion is called electrosychronous spin). When they enter the atmosphere, they enter a different refractive medium than empty space and must give up some of their energy. The result is the auroras we see.

The upwellings in the oceans are composed of magnetic, hardened magma. It appears in "bands" or strips, radiating out along the point of origin in alternating "north pole bands" and "south pole bands". The difference being only the direction of the north pole. Since the magma hardened in a magnetic field it took the magnetic direction of the field at the time of it's hardening. Since the bands alternate, it's obvious that the magnetic field was pointing in a different direction over time, north sometimes, south sometimes. It is unknown if the field collapses or simply rotates around to change direction. We may soon see.

The Van Allen Belts are the magnetic lines of flux surrounding the earth. They do hold charged particles but are not composed of them. I suspect that we can all be thankful that they are there. Without them a change in life as we know it is probable. Even with them in place, substantial cosmic (ionizing) radiation gets to us. Watch a cloud chamber sometime and see for yourself. A cascade shower from a molecule in the air struck by a cosmic particle is something to see, if you can.

Whim

[Gaz]

Im not sure if this is a silly question or not but why does the Earth actually undertake this changing of its magnetic field? Does anyone know? Why can't it just stay the same as it is?

I dont really know much about this topic but i just dont understand why the Earth would flip around its magnetic poles.

Could anyone give me any info about this?

Thanx,

Gaz

[Bridh Hancock]

Great topic!
Friends were concerned about this matter a few years ago. (Nothing seems to have happened, not even when the planets aligned&#33
I recall that the magnetic lines do not only reverse, (flip 180o), but have been shown to flip to other degrees, tho not to 90o. Memory is failing me on this matter. Maybe I can contribute more later, before the next Flip.

[Duane]

Is there any evidence for non-nutational changes in direction of the spin axis of the earth being coupled to the changes in the location of the magnetic axis?

Nothing that I have seen (and I assume you meant "non-ROtational"), and the timing of the pole reversals would argue against it. The changes in the spin axis are well understood now, and occur predictably. There is no evidence I am aware of that they are in sync with each other.

How are changes in magnetic field strengths and orientation as recorded in rocks distinguishable between plate tectonics effects and those of magnetic pole migration?

On the continents themselves, they aren't distinguishable. The only place where the north-south pattern is seen is on the ocean floor. Unfortunantly, this record only goes back about 200,000,000 years or so--older seafloor is subducted past that age.

First, magnetic poles do not cancel each other out. The strongest effects from a bipolar magnet are at it's poles, not at the center of the field.

True for a bar magnet, not true for a large, rotating body. You are right that the field lines do not cancel each other out, rather they extend down towards the centre of the Earth via its poles. That is why the field is weakest at the poles--and its at the poles that material from the solar wind is able to get to the atmosphere.

When they enter the atmosphere, they enter a different refractive medium than empty space and must give up some of their energy. The result is the auroras we see.

Well, no actually. The ions excite atoms in the air, which then glow. The colours are well understood, green for oxygen, blue for neon, etc. Also the auroras are the same in the north and south for this same reason. That is, they both are the direct result of ion exciting atoms in the atmosphere.

The rest of your comment is right on the mark though

why does the Earth actually undertake this changing of its magnetic field? Does anyone know? Why can't it just stay the same as it is?

Short answer is, we don't know. It may have something to do with the way the magnetic field in generated, but the process that causes the field is not well understood.