You may have heard that the earth’s magnetic
poles tend to move around.
I mean, so do the geographic poles, but magnetic
North and South are really mobile...and magnetic
North in particular is moving real fast.
Like, way faster than we thought it would.
And the scientific community is coming up
with some really exciting and creative ways
to figure out why.
The prevailing theory about why our planet
has a magnetic field in the first place is
because of what’s underneath the crust.
Dynamo theory, as it’s called, is the idea
that the molten metals of the outer core,
like iron are being convected—basically,
swirled—all around the Earth’s interior,
around the solid inner core.
This continuously creates electric currents
as charged particles move through this liquid
metal, and—in combination with the rotation
of the Earth—becomes what’s called a dynamo:
the source of a magnetic field.
This also explains why the magnetic poles
are not necessarily fixed points, because
the liquid that creates the magnetic field
is turbulent, and always shifting, the poles
move as the fluid does. Right now, for instance,
the North magnetic Pole has been slipping
down into Siberia for the past 150 years or
so...and it’s speeding up.
Our magnetic field actually has a name. It's called the
magnetosphere and it plays a crucial role
in making Earth a habitable planet.
It wards off much of space’s harmful radiation
like cosmic rays, acting like an essential
protective cloak around the Earth.
Which is one reason why scientists and governments are
so invested in knowing how it works and how
it will behave.
Like with the World Magnetic Model, for example.
This huge and innovative computer model of
Earth’s magnetic field behavior is used
by many international bodies as the guiding
standard on what the world’s magnetic field
is up to.
It combines sensor measurements of the field’s
strength and position, measurements which
are then used in simulations of the geodynamo’s
past, present, and future behavior.
The WMM releases updates to the model every
five years, but in 2019, it was forced to
release a mid-cycle update because magnetic
North has been sauntering vaguely downwards
much faster than anticipated...the perfect
example of the fact that even though we’re
measuring and predicting to the best of our
abilities, the geodynamo is too unpredictable
and complex to make a truly complete model
of it.
That uncertainty means scientists are also
looking for experimental ways to further probe
the Earth’s magnetic behavior, which typically
involves creating models of the Earth out
of liquid sodium.
Which is quite the commitment, because sodium
is a highly reactive metal that is extremely
difficult to handle and likes to spontaneously
burst into flame.
New sodium ball experiments are being used
in several labs worldwide, and—in combination
with improvements in computing and machine
learning—could help us gain more insight
into how Earth’s magnetic field will change...and
how we could prepare for when it does.
Because what does a shifting magnetic field
actually mean for us?
Flipped poles would mean that the names of
Earth’s hemispheres may be a bit confused
for a while, and compasses would point in
the opposite direction than they did previously.
But more importantly, as the poles shift around,
the magnetosphere could get weaker, with several
smaller magnetic poles popping up in other
places around Earth.
A weakened magnetosphere means many things:
the Northern lights will be visible in new
parts of the world, for a start.
All our satellites would need to be extra
fortified against radiation, or we risk them
getting totally fried by space weather like
solar wind.
Electronics here on Earth would be extremely
vulnerable to interference and destruction
by space radiation too, like our power grids.
And that’s not even mentioning the human
health effects of being exposed to much higher
degrees of radiation from space, which let me tell you, are not great.
We know from studying magnetic inclusions
that Earth’s magnetic field has flipped
entirely in the past— they trade places
about every 300,000 years, or so but it’s
been over double that since the last time
we know they flipped.
So we are long overdue for some magnetic migration
and it’s happening...fast.
And scientists are working hard to understand
why and how they move and what exactly it
may mean for us when they do.
The next update to the WMM is expected in
early 2020.
Do you want to know more about it when it
comes out?
Let us know down in the comments below.
Make sure you subscribe to Seeker for all
your science news, and for more on surprising
things inside the planet, check out this video
here.
As always—thanks for watching, and we’ll
see ya next time.
