this distortion produces a magnetic
field and includes loops that erupt
from the Sun’s surface and trigger
the formation of the Sun’s dramatic
sunspots and solar prominences.
This twisting action creates the solar
dynamo and an 11-year solar cycle
of magnetic activity.
When these loops and sunspot
magnetism break free from the
suns magnetic field they send what
we term the “solar wind” out into
space. From time to time it heads
directly towards planet Earth. The
Solar wind is a stream of charged
particles released from the upper
atmosphere of our star and mostly
consists of electrons and protons.
If ejected in the right direction
the solar wind will race Earthward
at great speed 300 – 1000kms per
second and faster in some cases.
Imagine a car travelling at over a
million miles an hour and you begin
to get the idea. Once it reaches
the Earth in 2-4 days it hits our
atmosphere and interacts with our
own magnetic field.
Our planet is protected by what
we term its magnetosphere, and
this is what initially protects us from
the blast of particles. As the wind is
first channelled past the Earth, our
magnetic field then acts as a mighty
bow to deflect these particles.
Then these particles pass the
Earth and re-connect, channelling
back towards us and attracting
them to the weakest portion of the
Earth magnetic field around the
poles. At the North Polar regions
we see the “Aurora Borealis”, and
the South Polar region we see the
“Aurora Australis”.
Our Earth has quite a complex
atmosphere but is primarily made of
Nitrogen and Oxygen with smaller
amounts of other gases. Critical
in Aurora formation though is that
Nitrogen and Oxygen.
In our atmosphere we actually
have 2 types of Oxygen; we have
atomic Oxygen and molecular
Oxygen as well as the Nitrogen.
What happens to create the
colours we see in the Aurora, is the
interaction between these gaseous
atoms and the particles from the
Solar wind the electrons.
Aurora Borealis as seen in the skies above a hotel near Reykjavik, Iceland.
Photo: Andrew Green
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