The term “Aurora” basically refers to a
natural light at very high altitudes in the sky. The aurora borealis (the
Northern Lights) and the aurora australis (the Southern Lights) have always
fascinated mankind, and people even travel thousands of miles just to see the
brilliant light shows in the earth's atmosphere. The auroras, both surrounding
the north magnetic pole (aurora borealis) and south magnetic pole (aurora
australis) occur when highly charged electrons from the solar wind interact with
elements in the earth's atmosphere.
Solar wind contains equal number of
proton and electrons along with heavier ions. It blows continuously from the
surface of the sun at a speed about 400km/hr. These winds scatter these ions in
the solar system also towards the earth.
Earth
is a gigantic magnet. It
is approximately the field of a magnetic dipole tilted at an angle of 11
degrees with respect to the rotational axis—as if there were a bar magnet
placed at that angle at the centre of the Earth. However, unlike the field of a
bar magnet, Earth's field changes over time because it is really generated by
the motion of molten iron alloys in the Earth's outer core (the geodynamo). The
Magnetic North Pole wanders, fortunately slowly enough that the compass is
useful for navigation
This magnetic field around the
earth is acts as a shield against the harmful solar winds. The charged
particles in solar winds may lead to severe damage to telecommunication
network. These particles would strip away the ozone layer, which protects the
Earth from harmful ultraviolet rays. Calculations of the loss of carbon dioxide
from the atmosphere of Mars, resulting from scavenging of ions by the solar
wind, are consistent with a near-total loss of its atmosphere since the
magnetic field of Mars turned off.
The charged particles when travel in space
with great velocity generates magnetic field which is influenced by earth’s
magnetic field. Hence they are driven by the magnetic field of the earth
towards the poles.
These charged particles enter the ionospheres at the poles. In the
ionosphere, the speeding electrons collide violently with gas atoms. This gives
the gas atoms energy, which causes them to release both light and more electrons.
In this way, the gases of the ionosphere glow and conduct flowing electric
currents into and out of the polar region. The electrons flowing back out don't
have as much energy as the incoming one hence the remaining goes to aurora.
-Article done by Akshay Nemade
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