WHY DO AURORAS
Roaliyah XII Science 5
Aurora is an electro-static phenomenon,
characterised by a bright glow and caused by
the collision of charged particles in the
magnetosphere with atoms in the Earth’s upper
Ultimately, the source lies in the solar wind, a
fast-moving stream of particles constantly
flowing from the Sun that carries the Sun’s
magnetic field out into space. The solar wind,
typically moving at 250 miles (400 kilometers)
per second, flows past Earth’s magnetic field
and molds it into an elongated bubble or
cavity, compressing its sunward side and
stretching its night side far beyond the Moon’s
Under certain conditions, the solar wind’s
magnetic field can merge with Earth’s, creating
electrical currents that drive protons and
electrons into the polar atmosphere. Powerful
events occurring on the Sun can drive
enormous changes in the solar
wind, increasing both its speed and density
and enhancing its effect on Earth.
An aurora is usually observed in the night
sky, particularly in the polar zone. For
this latter reason, some scientists call it a
“polar aurora” (aurora polaris).
Aurora Coloured light in the night sky
near the Earth’s magnetic poles, called
aurora borealis (northern lights) in the
northern hemisphere and aurora australis
(southern lights) in the southern
Northern lights is the name of a light
phenomenon often seen in the northern
regions. The lights have been around since
Earth formed an atmosphere The scientific
name for the phenomenon is “Aurora
Borealis”, aurora for short.
The southern lights or aurora australis, most
commonly seen in southern New Zealand. It
shows a typical red and green aurora, the
nearly vertical rays tracing the earth’s
magnetic field lines.
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