- [Narrator] Did you know that Earth has two north poles?
There's the geographic north pole,
which never changes,
and there's the magnetic north pole,
which is always on the move.
And right now it's moving faster than usual.
Over the last 150 years,
the magnetic north pole
has casually wandered 685 miles across northern Canada.
But right now, it's racing 25 miles a year
to the northwest.
This could be a sign
that we're about to experience something humans
have never witnessed before:
a magnetic polar flip.
When this happens, it could effect much more
than just your compass.
- Right now on the surface of the planet,
it looks like it's just a bar magnet.
Our compasses are just pointing toward one pole at a time.
There's a dominant two pole, dipole system.
- [Narrator] But sometimes, Earth doesn't always
just have a single magnetic north and south pole.
Evidence suggests that for hundreds to thousands
of years at a time,
our planet has had four, six
and even eight poles at a time.
This is what has happened
when the magnetic poles flipped in the past.
And when it happens again, it won't be good news for humans.
Now you might think that eight poles
must be better than two,
but the reality is that multiple magnetic fields
would fight each other.
This can weaken Earth's protective magnetic field
by up to 90% during a polar flip.
Earth's magnetic field is what shields us
from harmful space radiation
which can damage cells, cause cancer
and fry electronic circuits and electrical grids.
With a weaker field in place,
some scientists think this could expose planes
to higher levels of radiation making flights less safe.
This could also disrupt the internal compass
in many animals which use the magnetic field for navigation.
Even more extreme, it could make certain places
on the planet too dangerous to live.
But what exactly will take place on the surface
is less clear than what will undoubtedly happen in space.
Satellites and crude space missions
will need extra shielding
that we'll have to provide ourselves.
Without it, intense cosmic and solar radiation
will fry circuit boards
and increase the risk of cancer in astronauts.
Our modern way of life could cease to exist.
We know this because we're already seeing a glimpse of this
in an area called the South Atlantic Anomaly.
Turns out, the direction of a portion
of the magnetic field deep beneath this area
has already flipped.
Scientists say that's one reason why the field
has been steadily weakening since 1840.
As a result, the Hubble Space Telescope
and other satellites
often shut down their sensitive electronics
as they pass over the area.
And astronauts on the international space station
report seeing a higher number of bright flashes of light
in their vision, thought to be caused
by high energy cosmic rays
that the weaker field can't hold back.
Since experts started measuring
the anomaly a few decades ago,
it has grown in size.
It now covers a fifth of Earth's surface
with no signs of shrinking anytime soon.
This is so extreme that it could be a sign
we're on the brink of a polar flip
or we may already be in the midst of one.
But scientists remain skeptical, mainly because...
- The last time the poles reversed was 780,000 years ago
so we don't have a record of this.
- [Narrator] Turns out, 780,000 years
is over double the time Earth usually takes between flips.
- Since the last mass extinction,
there have been reversals roughly every 300,000 years.
- [Narrator] So, what gives?
Well, scientists haven't figured it out, yet.
It's unnerving to think that our modern way of life,
banking, the stock exchange, missile tracking, GPS,
relies on the outcome
of something we can neither predict nor control.
One study went so far as to estimate
that a single, giant solar storm today
could cost the U.S. up to
41.5 billion dollars a day in damages,
and that's with the Earth's magnetic field
at it's current strength.
It's frightening to even imagine
the devastation a storm would bring to an Earth
with a magnetic field only 10% as strong as it is now.
We may not be able to stop a polar flip,
but we can at least start to take measures
to minimize the damage.
The first step, figure out what's going on
with this wacky field.
On the hunt are the European space agency's
that are currently collecting the most precise data
on the strength of Earth's magnetic field.
Right now they could be our greatest hope
for solving this riddle.