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Old March 10th, 2017, 08:13 PM   #1
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What ancient clay jugs reveals about Earth's magnetic field

No doomsday stuff here, but really interesting.
What ancient clay jugs reveals about Earth's magnetic field
Time stamp in a jar: The intensity of the Earth's magnetic field spiked suddenly in the 8th century BC, according to a new analysis of ancient ceramic jar handles.


If anyone in the Near East had owned smartphones 2,700 years ago, they might have noticed something very weird.

Though compasses seem pretty steady, the orientation and strength of the Earth’s magnetic field vary sharply over time, sometimes shifting in the geological blink of an eye. A new study took advantage of conveniently time-stamped clay pots to create the most detailed reconstruction of the historical magnetic field yet, revealing some mysterious behaviors.

Direct measurements of this vital planetary shield date back almost two centuries, during which time we’ve seen the field weaken by about 10 percent, prompting some scientists to wonder if we’re at the beginning of a periodic flip, where north becomes south and south becomes north.

Other recent reminders of the field’s dynamic nature include the magnetic north pole wandering over 900 miles since 1990, and at least four “geomagnetic jerks” within the last fifty years, where the field’s rate of change jumped suddenly before returning to normal.

At the opposite time extreme from these very-short-term jerks are the multi-million year trends recorded in the ocean floor. Scientists can study fossilized remnants of the magnetic field at the bottom of the sea, thanks to iron-laden minerals that line up with the field when molten, and get locked into that orientation upon cooling. Those deep-underwater records show evidence of pole-flips going back about 175 million years.
More: What ancient clay jugs reveals about Earth's magnetic field - CSMonitor.com
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Old March 10th, 2017, 08:38 PM   #2
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Two interesting things. Geologists, by studying the orientation of ferromagnetic crystals in rocks have seen at least two times that the earth's magnetic field has flipped. No one is sure how fast it was. But what a mess during the transition, including the possibility of the earth losing its protection from solar particles and UV rays for a while.

https://www.nasa.gov/topics/earth/fe...eReversal.html

And something I was personally involved in and had to learn way more about the subject than I ever wanted to:

While working on one of the early heavy oil horizontal drilling programs where the wells were spaced quite close together, we discovered that the two directional drilling survey companies we contracted were using different magnetic declinations, that is the difference between the geographic and magnetic north pole.

Anyway they both could justify their number so as so often happened, a problem that no one knew anything about was thrown at me. So I got to learning about it and it turns out that for many years preceding this time, the magnetic north pole had circled around a spot in the eastern part of the Canadian Arctic and one company used an extrapolation based on one set of data. The other company used an extrapolation of some newer data which incorporated the north pole suddenly moving eastward at a relatively high rate.

To make a long story short, we ended up having to get an instrument and actually measure the magnetic declination at our site.

The last I heard, the magnetic north pole left Canadian territory and is heading to Greenland.
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Old March 10th, 2017, 10:00 PM   #3
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Quote:
Originally Posted by imaginethat View Post
No doomsday stuff here, but really interesting.
What ancient clay jugs reveals about Earth's magnetic field
Time stamp in a jar: The intensity of the Earth's magnetic field spiked suddenly in the 8th century BC, according to a new analysis of ancient ceramic jar handles.


If anyone in the Near East had owned smartphones 2,700 years ago, they might have noticed something very weird.

Though compasses seem pretty steady, the orientation and strength of the Earth’s magnetic field vary sharply over time, sometimes shifting in the geological blink of an eye. A new study took advantage of conveniently time-stamped clay pots to create the most detailed reconstruction of the historical magnetic field yet, revealing some mysterious behaviors.

Direct measurements of this vital planetary shield date back almost two centuries, during which time we’ve seen the field weaken by about 10 percent, prompting some scientists to wonder if we’re at the beginning of a periodic flip, where north becomes south and south becomes north.

Other recent reminders of the field’s dynamic nature include the magnetic north pole wandering over 900 miles since 1990, and at least four “geomagnetic jerks” within the last fifty years, where the field’s rate of change jumped suddenly before returning to normal.

At the opposite time extreme from these very-short-term jerks are the multi-million year trends recorded in the ocean floor. Scientists can study fossilized remnants of the magnetic field at the bottom of the sea, thanks to iron-laden minerals that line up with the field when molten, and get locked into that orientation upon cooling. Those deep-underwater records show evidence of pole-flips going back about 175 million years.
More: What ancient clay jugs reveals about Earth's magnetic field - CSMonitor.com
The magnetic flip has happened thousands of times in the past and Earth's magnetic field is diminishing as I write and another flip is expected in the not too distant future. The magnetic North Pole is not even close to the geographic North Pole and well south of it and heading further south. Just another thing to worry about.

What causes the flip? There is a solid inner core and a liquid outer core and the inner core is unstable and inverts at a period of some tens of thousands of years. Half way through the flip the Earth has no magnetic field and we are bombarded by the solar wind. On a good note: when the flip occurs it happens relatively fast.

edit: maximum precession of the earth's axis is around 25 degrees and we are at maximum precession as I write, the Earth is nothing more or less than a gyroscope

Last edited by Twisted Sister; March 10th, 2017 at 10:32 PM.
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