Earth's Magnetic Field

The Earth’s Magnetic Field
 Earth's magnetic field — also known as the

geomagnetic field — is generated in our planet's interior
and extends out into space, creating a region known as the
magnetosphere.
 Without the magnetic field, life on Earth as we know it
would not be possible as it shields us all from the constant
bombardment by charged particles emitted from the
sun — the solar wind. (To learn what happens to a planet
when it loses its magnetic field, you only need to look
at Mars.)
 Earth has two sets of poles, geographic pole and
magnetic poles. Earth's magnetic field can be visualized if
you imagine a large bar magnet inside our planet, roughly
aligned with Earth's axis. Each end of the magnet lies
relatively close (about 10 degrees) to the geographic North
and South poles. Earth's invisible magnetic field lines
travel in a closed, continuous loop and are nearly vertical
at each magnetic pole.
And just to make things that little more confusing, what we call
the North Magnetic Pole is actually a south magnetic pole… bear
with me on this. Magnetic field sources are dipolar, meaning they
have a north and south pole. And when it comes to magnets,
opposite poles (N and S) attract while other poles (N and N, S and
S) repel. So when a compass points north, it is actually attracted
to the south magnetic pole which lies close to the Geographic
North Pole, according to Physicist Christopher Baird's science
FAQ website(opens in new tab)
Unlike the geographic poles, Earth's magnetic poles are not fixed
and tend to wander over time. British polar explorer James Clark
Ross first identified the Magnetic North Pole on the Boothis
Peninsula in Canada's Nunavut territory in 1831, according to the
Antarctic travel site Antarctic Logistics
Since its discovery, the magnetic north pole moves about 25 miles
(40 kilometers) a year in a northwest direction according to
the Royal Museums Greenwich(opens in new tab). Whats more,
Earth's magnetic poles have also 'flipped' whereby north becomes
south and south becomes north. These magnetic reversals occur
at irregular intervals every 200,000 years or so.
CAUSES OF EARTH’S MAGNETIC
FIELD
Earth's magnetic field is generated by what is known as the
geodynamo process. According to National Geographic(opens in
new tab), for a planet to generate its own magnetic field by the
geodynamo process, it must have the following characteristics:
 The planet rotates fast enough
 Its interior must have a fluid medium
 The interior fluid must have the ability to conduct
electricity
 The core must have an internal source of energy that propels
convection currents in the liquid interior.
The generation of Earth's magnetic field occurs deep within the
Earth's interior, in a layer known as the outer core to be precise.
Here the convective energy from the slow-moving molten iron is
converted to electrical and magnetic energy, according to the U.S.
Geological Survey(opens in new tab). The magnetic field then
induces electric currents which in turn generate their own
magnetic field which induces more electric currents, in a positive
feedback loop.
HOW EARTH’S FIELD PROTECTS LIFE
Our protective magnetic "bubble," known as the magnetosphere,
protects us from harmful space weather such as solar wind.
Without the magnetosphere, the solar wind would erode our
atmosphere, devoiding our planet of the life-giving air we
breathe.
According to NASA(opens in new tab), the magnetosphere also
protects Earth from large quantities of particle radiation emitted
during coronal mass ejection (CME) events and also from cosmic
rays — atom fragments — raining down on Earth from deep
space. The magnetosphere repels harmful energy away from
Earth and traps it in zones called the Van Allen radiation belts.
These donut-shaped belts of radiation can swell when the sun's
activity increases.
But our protective shield is not completely invincible.
During particularly strong space weather events such as high
solar winds or large CMEs, Earth's magnetic field is disturbed
and geomagnetic storms can penetrate the magnetosphere and
lead to widespread radio and power blackouts as well as
endangering astronauts and Earth-orbiting satellites.
In 1859, a large solar storm known as the Carrington Event
caused widespread telegraph system failures and in 1989, a CME
accompanied a solar flare and plunged the entire province of
Quebec, Canada into an electrical blackout that lasted around 12
hours according to a NASA statement(ope
MAGNETIC POLES REVERSALS
According to Science Daily(opens in new tab), in the last 200
million years alone, Earth's magnetic poles have reversed
hundreds of times in a process where north becomes south and
south becomes north.
The magnetic poles flip approximately every 200,000 to 300,000
years(opens in new tab) according to NASA, though it has been
more than twice that long since the last reversal. Earth's most
recent magnetic reversal occurred approximately 790,000 years
ago so we are rather overdue for another. But don't worry, the
magnetic poles won't just switch overnight, it can take hundreds
or even thousands of years for the poles to flip.
MAGNETIC FIELDS IN OTHER PLANETS
Earth is not the only planet in the solar system to possess a
magnetic field. Jupiter, Saturn, Uranus and Neptune all exhibit
magnetic fields far stronger than Earth's, according to Union
University(opens in new tab), though the underlying mechanisms
driving these magnetic fields are not yet completely understood.
Not every planet is fortunate enough to have a protective
magnetic layer. Mars does not have enough inner heat nor does it
possess the liquid interior required to generate a magnetic
field. Venus, on the other hand, has a liquid core but does not spin
fast enough to generate a magnetic field.

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The Earth’s Magnetic Field

 Earth's magnetic field — also known as the

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