N
ature
has
an
uncanny knack of
producing some of
the most spectacular
astronomical events we can witness,
the likes of Solar eclipses, meteor
showers and other phenomenon
that never fail to impress. There is
one event however, that once you
witness it, it will be burnt into your
memory and will stay with you for
the rest of your life, this is witnessing
the Aurora.
Aurora is a Latin word for “Sunrise
or Dawn” and in Roman mythology
Aurora was the goddess of the
dawn. “Borealis” means pertaining
to the North and “Australis” to the
South.
Auroral displays have been
known about for 1000’s of years
and for those cultures in the
Polar regions of the Earth they
have witnessed some of the most
breathtaking displays seen, but the
Aurora, provided conditions are
right, can be seen from many lower
latitude locations around the world
provided conditions are right.
To start to explain it we must first
look at our own star, the Sun.
Our sun is the powerhouse at the
heart of the Solar system a huge
ball of gas with a nuclear furnace
at its heart. Accounting for 99% of
the mass of our solar system the
sun is by far the largest body in our
local neighbourhood. The sun itself
has a diameter of about 864,938
miles and is primarily composed
of Hydrogen. In the core region
the Hydrogen is converted into
Helium by a process called nuclear
fusion the by-product of which is
energy and heat. The Sun is losing
approximately 4million tonnes of
itself each and every second as
energy and if we could turn that
into power we could perhaps keep
a city the size of New York or London
in electricity for many 1000’s of
years. The Sun is very powerful!
An illustration of the structure of the Sun.
20
20
As with the Earth and the other
planets, the Sun also rotates about
its axis, but in a different way to
planet Earth. Here on Earth we say
the earth revolves around each
and every 24 hours (23h 56m4s)
regardless of where you are, the
sun is different! It has what we call
“differential rotation”. All the matter
in the Sun is in the form of gas and
at high temperatures, plasma. This
makes it possible for the Sun to rotate
faster at its equator than it does at
higher latitudes and this is where the
sun begins to have an effect. At the
polar regions of the sun it rotates in
approximately 35 days and at the
solar equator in approximately 25
days and this gives rise to distortions
in the sun and its magnetic field.
This rotational difference in the
Sun causes its magnetic field lines
to become twisted and much
distorted, imagine a rubber band
that has been continually spun
and twisted together. Over time
Graphic: Kelvinsong via Wikipedia.com
www.RocketSTEM.org