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Weakening field
The planet's magnetic field is generated by the churning of liquid iron in the core. Without the field, life on the planet would be much different, if not impossible: This invisible shield protects the Earth's surface from deadly cosmic radiation.
Right now, the field is undergoing a weakening, and no one is sure why. The South Atlantic Anomaly, a region of the magnetic field that stretches from South Africa to Chile, is particularly weak, Tarduno said, so scientists have become interested in figuring out what might be going on in the core underneath that area.
The problem is that before about 160 years or so ago, with the advent of magnetic observatories and (eventually) satellite observations, there weren't many records of what the magnetic field looked like in the Southern Hemisphere, Tarduno said. Ninety percent of the data that does exist comes from the northern half of the planet. To start to rectify that disparity, Tarduno and his team excavated clays from the Limpopo River Valley of Zimbabwe, South Africa, and Botswana. In times of drought hundreds to thousands of years ago, Bantu-speaking farmers would burn down their clay huts and grain bins in ritualistic ceremonies. Unbeknown to these ancient farmers, the fire heated the magnetic minerals in the clay and locked into place a record of the strength and orientation of the field at that time. Now, researchers can study those properties to find out what the magnetic field was doing at that moment in time.
Locked in clay
The excavations unearthed these burnt clays as long ago as A.D. 425, Tarduno said, providing the longest record yet of the magnetic field in southern Africa. The data show that the magnetic field experienced sudden directional shifts between A.D. 400 and 450, and then again between A.D. 750 and 800. Between about A.D. 1225 and 1550, the field noticeably weakened. The first two shifts might also indicate a weakened field, Tarduno said, but more research is needed to determine the magnetic intensity in those time frames. The researchers reported their findings Feb. 15 in the journal Geophysical Research Letters.
What these shifts suggest is that what is going on in the Southern Hemisphere's magnetic field today may have happened before, Tarduno said.
originally posted by: intrptr
Theres no ground zero for magnetic field. Earths mass, the molten, spinning core is a dynamo, generating a field like a spinning motor. As long as the motor is on, the axis and spin rate never change, the earths magnetic field will continue, even if it 'flips'.
So what, the compass needles will point the wrong direction. Oh, and a zillion satellites will lose their way.
That could be interesting.
originally posted by: JoshuaCox
a reply to: lostbook
I wonder if it couldn’t be the electric grid that is messing it up..
The earth went from almost no elecric fields besides the earth itself and those life gives off.
To powerlines. Nuclear plants, hadreon colliders and such..
Maybe that stuff matters o a macro scale
originally posted by: intrptr
Theres no ground zero for magnetic field. Earths mass, the molten, spinning core is a dynamo, generating a field like a spinning motor. As long as the motor is on, the axis and spin rate never change, the earths magnetic field will continue, even if it 'flips'.
So what, the compass needles will point the wrong direction. Oh, and a zillion satellites will lose their way.
That could be interesting.
originally posted by: smurfy
originally posted by: intrptr
Theres no ground zero for magnetic field. Earths mass, the molten, spinning core is a dynamo, generating a field like a spinning motor. As long as the motor is on, the axis and spin rate never change, the earths magnetic field will continue, even if it 'flips'.
So what, the compass needles will point the wrong direction. Oh, and a zillion satellites will lose their way.
That could be interesting.
There's a wee bit more. The iron in the core is thought to be solid, and that there is an outer liquid core that carries ionized iron that moves around the outer core in a very slow process, and that is thought what causes the magnetic field, which then is variable, and the outer core is probably asymmetrical in its motion.
originally posted by: YouSir
originally posted by: smurfy
originally posted by: intrptr
Theres no ground zero for magnetic field. Earths mass, the molten, spinning core is a dynamo, generating a field like a spinning motor. As long as the motor is on, the axis and spin rate never change, the earths magnetic field will continue, even if it 'flips'.
So what, the compass needles will point the wrong direction. Oh, and a zillion satellites will lose their way.
That could be interesting.
There's a wee bit more. The iron in the core is thought to be solid, and that there is an outer liquid core that carries ionized iron that moves around the outer core in a very slow process, and that is thought what causes the magnetic field, which then is variable, and the outer core is probably asymmetrical in its motion.
Ummm...I'm wondering how much truth there is in that solid core theory...
It seems to me that the core would contain the highest heat and pressure...if we have liquid iron that spews from the earth's mantle to the crust...wouldn't the iron at the center be liquid as well...?
The core is under considerably more pressure...if you compress liquid iron while increasing heat...wouldn't you end up with more dense liquid iron and not a solid...Per Se...?
With increased pressure in all directions inward...the viscosity would no doubt increase in conjunction with the density...
Still...I would think you would end up with a "rest liquid"...rather than an amorphous solid...an increased viscosity liquid in a rest state due to the increased density and pressure...
Chika...chika...there goes that singular seed rattling around that gourd again...
Perhaps I could get it to form a beat...
Yousir
originally posted by: YouSir
Ummm...I'm wondering how much truth there is in that solid core theory...
It seems to me that the core would contain the highest heat and pressure...if we have liquid iron that spews from the earth's mantle to the crust...wouldn't the iron at the center be liquid as well...?
The core is under considerably more pressure...if you compress liquid iron while increasing heat...wouldn't you end up with more dense liquid iron and not a solid...Per Se...?
Yousir