earth's magnetic feild

[Gaston]

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

 

[3v0]

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

 

[Gaston]

and what would be the cause of this change?

 

[Hero999]

Convection in the earths core?

I don't think anyone really knows.

How long does it take for the change to occur?

 

[hentai]

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.

 

[3v0]

From Why Does Earth's Magnetic Field Flip?

Our planet's magnetic field reverses about once every 200,000 years on average. However, the time between reversals is highly variable. The last time Earth's magnetic field flipped was 780,000 years ago, according to the geologic record of Earth's polarity.

3v0

 

[Gaston]

well if the magnetic field is weakening. would't that add to the global warming effect by letting more radiation hit us?

 

[dknguyen]

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.

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.

 

[Sceadwian]

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.

 

[justDIY]

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

 

[mvs sarma]

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?

 

[Nigel Goodwin]

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?

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

 

[AllVol]

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.

 

[Hero999]

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.

 

[johankj]

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.

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.

 

[3v0]

If our use of electricity was to blame how do you explain the previous numerous flips indicated by the magnetic record in the rock.

It is too easy to talk about the things we can do little about, and ignore that which we could actually have an impact on.

Ocean pollution.
The export of polluting industries to other countries.
And maybe the leverage of multinationals that keep us using fossil fuels.

 

[Hero999]

No, but our use of electricity is making it happen even faster than before!

I'm being sarcastic of course!

Don't astronauts have shields to protect them from the radiation?

 

[3v0]

Some days I find it hard to tell.

I do not know it for a fact, but have been told that anyone who spends time in space is infertile.

 

[Sceadwian]

That's an Urban Myth, although not entirely without warrant, ionizing radiations exposure outside of Earths magnetic is increased, though to exactly what extent I'm not sure. Nasa and other space agencies (Russia especially) have been watching it for years. I've never heard any reports of people growing third arms or an increased cancer rate.
One thing I have heard which was confirmed was that some/most Astronauts experience visual flashes of light randomly because of highly charged particles passing through the eyeball emitting photons on the way. How's that for creepy.
The magnetic field changing polarity would be pretty bad for power grids. Without it solar flare effects on power outages would increase dramatically.

 

[justDIY]

One thing I have heard which was confirmed was that some/most Astronauts experience visual flashes of light randomly because of highly charged particles passing through the eyeball emitting photons on the way. How's that for creepy.

NASA's also found that many of their older generation astronauts have developed cataracts, directly linked to radiation exposure while in orbit.