is it true that the earth's magnetic poles change from north to south over thousands of years?

 

I have seen TV specials that claim they do. IIRC they know this because they examined rocks and the magnetic field within them changed. The time between flips is greater then a few thousand years.

The problem is that during the flip we loose the protection provided by the magnetic field and are exposed too loads of radiation.

3v0

 

and what would be the cause of this change?

 

Convection in the earths core?

I don't think anyone really knows.

How long does it take for the change to occur?

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the time interval between shifts is mostly a guess some say 5000 years some say 5 million. But if it will happen it could mean very well the end or at least it will leave us really scared. Way back chinese knew that magnetism promotes vigor in all life. And i dont wont to think about the effects on the magnetosphere.
It also seems that the strenght of Earth's magnetic field is fading... and it is said to have droped more than a half from the time the big lizards ruled.

 

From Why Does Earth's Magnetic Field Flip?
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well if the magnetic field is weakening. would't that add to the global warming effect by letting more radiation hit us?

 

I won't say anything about the "magnetism promotes the vigor of life" stuff since it's all up in the air except that that if it does have an effect it not a necessary one (it's possible to have unhealthy life ya know), but the magnetosphere protects us from the solar wind if I'm not mistaken. I'm not sure what happens in between flips when it's almost zero, whether it occurs fast enough so it doesn't cause mass extinction.

 

Gaston, it wouldn't matter, the radiation itself would kill or cause mass mutations in life on earth regardless of amount of heat it would add. The only theory I've heard that explains the changes in the magnetic field is that the bulk of the strength of the field is caused by the convection of the earths liquid iron core, every now and then the convection patterns change and reverse, and the magnetic field goes with it.

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of all the catastrophes waiting to befall our humble planet, I like the Yellowstone eruption theory the best.

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HI, i have a fundamental doubt--
all of us know that a magnetic compass shows redmaked side towards north
now if suppose we are at noth pole or south pole (deadcentre-- how will magnetic compass behave? i am rather fond to know?

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You haven't read enough adventure books, or watched enough films - compasses are useless anywhere near the poles.

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Question:

If the earth's magnetic field does its best JK FF imitation, will:

Electric motors suddenly run backwards --
Will all the electromagnetic waves that have been broadcast suddenly come back --
Will opposities no longer attract --
Will the right-hand rule become leftist --
Will electrons flow from positive to negative --

I have googled these questions, but got no response. Please help me. I have a test coming up in a couple of hundred thousand years.

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I suspect human activity is to blame, the magnetic fields given off by the world's electricity supplies are interfering with the the currents circulating in the earth's core by electromagnetic induction.

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No, it wouldn't sterilize our planet, fortunately.

What we would see is aurora all over the planet, migrating birds getting lost, sea-turtles stranded, etc... (They rely on the magnetic field for navigation) You could speculate on an increase in cancer caused by radiation, but not mass death as a direct cause a magnetic reversal.

Just think of the astronauts and cosmonauts that spend months in space, partially unprotected by our planets magnetic field. Their biggest problem is loss of bone-mass due to the lack of gravitation, not the exposure to space radiation.