| Topic: |
Science > Physics |
| User: |
"John Schutkeker" |
| Date: |
10 Sep 2006 10:10:17 AM |
| Object: |
"Earthspots" |
If there were such a thing as "earthspots," ie. sunspot-like locations,
associated with the reversal of the magentic field, where flux loops poke
through the outer core into the mantle, would it be possible to detect them
with existing magnetometers?
.
|
|
| User: "Sorcerer" |
|
| Title: Re: "Earthspots" |
10 Sep 2006 12:45:47 PM |
|
|
"John Schutkeker" <jschutkeker@sbcglobal.net.nospam> wrote in message
news:Xns983A71A87B6Flkajehoriuasldfjknak@207.115.17.102...
|
| If there were such a thing as "earthspots," ie. sunspot-like locations,
| associated with the reversal of the magentic field, where flux loops poke
| through the outer core into the mantle, would it be possible to detect
them
| with existing magnetometers?
Yeah, there's one in North Alaska....
.
|
|
|
|
| User: "tadchem" |
|
| Title: Re: "Earthspots" |
10 Sep 2006 11:02:39 AM |
|
|
John Schutkeker wrote:
If there were such a thing as "earthspots," ie. sunspot-like locations,
associated with the reversal of the magentic field, where flux loops poke
through the outer core into the mantle, would it be possible to detect them
with existing magnetometers?
Existing magnetometers have mapped out the earth's magnetic field at
the surface:
http://en.wikipedia.org/wiki/Image:IGRF_2000_magnetic_declination.gif
The only spots that resemble a sunspot are the geomagnetic poles - one
is shown in the picure just south of Tasmania on the coast of
Antarctica, the other is north of Canada.
Because the earth's magnetic field is so inhomogeneous, variations have
to be examined locally:
http://en.wikipedia.org/wiki/Image:Brunhes_geomagnetism_western_US.png
A "magnetic field reversal" is an event. It implies that there is a
time such that the magnetic field of the earth pointed in one direction
before that time and in the opposite direction after that time:
http://en.wikipedia.org/wiki/Geomagnetic_reversal
There have been several reversals within the existence of the genus
Homo on earth, none of which appear to have resulted in consequences
dire enough to leave gological evidence of a catastrophe. In fact the
reversals are *only* detectable from careful analysis of the magnetic
orientation of ferromagnetic particles in sedimentary rocks or cooled
lava
The stochastic nature of the variation *since* the last reversal
http://en.wikipedia.org/wiki/Image:Brunhes_geomagnetism_western_US.png
and the irregularity of timing of reversals
http://en.wikipedia.org/wiki/Image:Lowrie.gif
indicate that forecasting the *next* reversal would be a fool's errand.
Tom Davidson
Richmond, VA
.
|
|
|
|
|
