- 4390 - MAGNETIC POLES FLIP - should we worry? - Why do Earth's magnetic poles flip? Every so often, Earth's magnetic poles completely flip. What causes this to happen? And how do these reversals affect life on Earth?
------------------- 4390
- MAGNETIC POLES
FLIP - should we worry?
-
- Earth, our rocky, watery oasis in the
cosmos is the ideal place for life to flourish for a number of reasons. We sit at just the right distance from our
home star for liquid water to exist on the planet's surface. The gravitational
pull of other large planets helps protect us from apocalyptic collisions with
wandering meteorites. And the planet's magnetic field encircles Earth with a
protective barrier that shields us from charged particles hurtling through
space.
-
- Earth's magnetic field is generated by the
complex flow of molten metallic material in the outer core of the planet. The
flow of this material is affected both by the rotation of Earth and the
presence of a solid iron core, which results in a dipolar magnetic field where
the axis roughly aligns with the rotational axis of the planet.
-
- Hidden in the chemical composition of
ancient rocks are clues that Earth's magnetic field is a dynamic, shifting
phenomena. Cooling magma rich in iron minerals is pulled into alignment with
Earth's magnetic field, similar to how a needle is pulled to point towards
north on a compass. The study of ancient geomagnetic fields recorded in rocks
is the subject of a discipline known as "paleomagnetism."
-
- Paleomagnetic research has provided
scientists with the knowledge that Earth's magnetic field has shifted and even
reversed in polarity many times in the geological past. But why?What causes the
magnetic poles to flip?
-
- Earth's magnetic field varies at very short
timescales and extremely long ones, ranging from milliseconds to millions of
years. The interaction of the magnetic field with charged particles in space
can alter it at short timescales, while perturbations in the magnetic field at
longer timescales are caused by internal processes unfolding in the outer
liquid core of the Earth.
-
- Fluctuations in the magnetic field caused
by the movement of metallic material in the outer core have brought about full
reversals of the magnetic field's polarity in Earth's past. Paleomagnetic
studies which have studied previous states of the magnetic field have shown
there are two possible states of polarity, the current 'normal' state, where
the lines of force of the field enter towards the center of the Earth in the
northern hemisphere and exit towards the outside of the Earth in the southern
hemisphere. The inverse, or 'reverse' polarity is also equally as probable and
stable.
-
- Paleomagnetic studies have shown that
polarity reversals of Earth's magnetic field are not periodic and cannot be
predicted. This is largely because of the behavior of the mechanisms that are
responsible for it. The flow of the
metallic fluid (mostly molten iron) in the outer core of the Earth is chaotic
and turbulent.
-
- Polarity reversals occur during periods of
low geomagnetic field intensity, during which the intensity of the dipolar
component drastically decreases, and the structure of the field is unstable. The transitory period of polarity reversal appears
as a geologically instantaneous (below the geological resolution), with a
duration spanning up to a few thousand years.
-
- When the magnetic field is prone to
flipping, it is in a state of reduced intensity, resulting in a greater
exposure of Earth's atmosphere to solar wind and cosmic rays in the form of
charged particles. A recent study showed that during the Laschamps excursion, a
recent period of low magnetic field intensity which occurred only 41,000 years
ago, the global cosmic ray flux reaching the Earth's atmosphere was up to three
times higher than today's value.
-
- Currently, there is no significant evidence
of a correlation between mass extinctions of life on Earth and geomagnetic
polarity reversals. However, linking rates of species extinction and speciation
with periods of low magnetic field intensity is hindered by uncertainties in
the known timescale of these magnetic 'flips'.
-
- Magnetic reversals happen frequently on
geological timescales (several hundred times in the past 160 million years),
while recorded mass extinction events occur every hundred million years or so
(much less frequently).
-
- In terms of human civilization, it is not
the shifting of the magnetic poles that is directly concerning, but the
resulting period of reduced geomagnetic field intensity. Society is growing
increasingly reliant on technology, and the effects of a reduced magnetic field
intensity should be seriously considered by governments and international
organizations.
-
- In this configuration there would be a
notable increase in the penetration of charged particles into the magnetosphere
at altitudes closer to the Earth's surface, with important repercussions on our
technological world.
-
- The risks to which our planet and
civilization is exposed could have significant impacts on civil society, how we
do commerce, security, communications, power infrastructure, satellites and the
lives of people in low Earth orbit. Unfortunately, the sporadic nature of
magnetic variations and reversals means we cannot predict when exactly this
will happen, all we know is that it will happen.
-
-
March 16, 2024 MAGNETIC POLES
FLIP - should we worry? 4390
------------------------------------------------------------------------------------------
- Comments appreciated and
Pass it on to whomever is interested. --------
--- Some reviews are at: -------------- http://jdetrick.blogspot.com -----
-- email feedback, corrections, request for
copies or Index of all reviews
--- to:
------
jamesdetrick@comcast.net
------ “Jim Detrick” -----------
--------------------- --- Monday, March 18, 2024
---------------------------------
No comments:
Post a Comment