Re: Planet X: (Science News) A Comet's Odd Orbit Hints at Hidden Planet
In Article <Pine.BSI.4.05L.10105052131380.6502-100000@shell.golden.net> John Latala wrote:
> Planet-X then there's no way it's magnetic field
> is changing things on Earth. Magnetic fields fall
> off a lot faster than gravitational fields. You can
> see that right here in our solar system since the
> Sun's magnetic field doesn't reach us but it's
> gravitational field does.
Oh? What causes our magnetic field to point in the direction it does in
the first place? What giant magnet in the sky are we and the other
planets aligned with? And if the Earth's core is not affected by the
relative distance of Planet X, then why is it our magnetic field was
STRONGEST approximately 2,000 years ago (1/2 of 3,657 years or so) and
is becoming diffuse, rapidly?
Date: Mon, 10 Nov 1997 15:06:01 GMT
From: Larry Newitt <newitt@geolab.nrcan.gc.ca>
Subject: re: decay of the earth's magnetic field
I am not familiar with the article by Barnes in the SIS
Review, but the decrease in the earth's magnetic field to
which he referred is well-known. That is not to say that
the strength of the magnetic field is decreasing by the
same amount everywhere. Measurements of the
magnetic field strength are routinely made at different
places on the earth show, and show different rates of
decrease; in fact, some places show an increase.
However, mathematical analyses of the observations,
which are routinely done every few years, show an
overall decrease in what is called the "dipole moment"
of the magnetic field. (See for example, C.E. Barton,
Journal of Geomagnetism and Geoelectricity, v 49,
123-148, 1997.) This decrease is approximately
linear, not exponential. If it were to continue, the dipole
moment would become zero in about 1250 years, but
Barton points out that the dipole appears to be recovering
from an historic high that occured about 2000 years ago,
so there is no reason to believe that the decrease will
continue indefinitely.