Don’t start running around like your hair’s on fire, but this might
actually matter. The Earth’s magnetic field is so discombobulated over
South Africa that some scientists believe we’re seeing the opening
strains of a planet-wide polarity change.
What have scientists observed?
We already knew that the poles of the Earth’s magnetic field
sometimes reverse, which is to say their direction flips from herding
particles in to shooing them out, or vice versa. And the Earth’s
magnetic field isn’t perfectly even, either. It’s sort of lumpy and thin
in places. This is because the innards of our planet aren’t perfectly
evenly distributed. There’s one particular region of the planet, toward
the South Pole, where the liquid iron core meets with a hot, dense patch
of the mantle. Studies of the planet’s magnetic field show that its
poles are reversed over that patch.
Michael Osadicw/John Tarduno, CC
BY-ND
Above it, that ferromagnetic weirdness results in an
overlapping region of weirdness in the planet’s magnetic field called
the South Atlantic Anomaly. The protective Van Allen belts there get
really weird; they fade in intensity, and they dip way down close to the
surface.
That region poses an annoying, but well understood problem
for space travel and satellites. Hubble doesn’t take observations when
it’s orbiting above the Anomaly. There’s a report that in 2012, SpaceX’s
Dragon spacecraft experienced magnetic interference from the Anomaly
and had to reboot systems as a result. The Anomaly may even be
responsible for how Hitomi spun itself apart.
Why is all this happening? What’s perturbing the magnetic field? The
core is liquid, it’s moving inside the planet, and it changes the
contours of the magnetosphere along with it. Earth’s magnetic field has
been weakening sharply over the last 160 years, right over the South
Atlantic Anomaly.
Evidence from fired clay from Bantu-speaking civilizations some
5,000 years ago tells us that the planet’s magnetic field was acting
just like this, right there over South Africa, back then. Modeling tells
us that this magnetic behavior preceded a planetary-scale flip in
geomagnetic alignment that would have resulted in extreme
electromagnetic strangeness on the surface. Basically, the Anomaly got
big enough that it took over, and flipped the entire planet’s poles
inside out.
NASA’s simulation of what Earth’s magnetic fields might look like during a geomagnetic reversal. Yikes.
What does a geomagnetic pole reversal mean for us?
This isn’t going to be one of those end-of-the-world articles. That
said, if the poles do flip, we could be in for some electromagnetically
interesting times. Magnetic fields deflect electrons, which would change
how electricity behaves on a subtle level. The inconsistencies in the
planet’s magnetosphere could kneecap satellite observations and act like
a poltergeist in computerized systems.
“Such a major change would affect our navigation systems,”
according
to two geophysicists from the University of Rochester, “as well as the
transmission of electricity. The spectacle of the northern lights might
appear at different latitudes. And because more radiation would reach
Earth’s surface under very low field strengths during a global reversal,
it also might affect rates of cancer.”
Tin foil is electrically conductive, though, so make sure
you keep your head well grounded. If you shape the foil right, it’ll act
like a Faraday cage around your skull and keep the polarity switch from
frying your brain.
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