The Northern Lights The
Northern Lights, or 'Aurora Borealis', are a natural light show
that can be seen at the North Pole. They also occurs at the
South Pole, where they are called the 'Southern Lights' or 'Aurora
Australis'. They are a spectacular display of different shades
and colours of light rapidly moving in the night sky.
The lights occur when particles from the sun interact with the Earth's atmosphere. These particles are what's know as 'solar wind', and are quickly moving charged particles that are emitted from the Sun. The solar wind is very closely linked to the 11 year solar sunspot cycle and to solar flares. Most of the world is protected from these particles by the magnetic field of the earth, except the Poles. Here the solar wind can interact with the Earth's atmosphere.
When the charged particles collide with the Earth's air molecules,
their energy is emitted as light. As the solar wind only interacts
with the air at the Poles, this is where we see the lights, in a
ring around the Poles called the 'auroral ovals'. When there are
more particles travelling from the sun, the ring expands and northern
lights have been reported in the UK. They are more common in the
north of Scotland, as it is further north.
The lights occur very high above the Earth, usually over 40 miles
high. This is even higher than jet planes fly, but the lights have
been seen as high as 600 miles above Earth, which is even higher
than space shuttles fly.
The solar wind can also have an effect on our telecommunications.
Many radio signals are 'bounced' around the Earth
using the top of the atmosphere. The charged particles of the solar
wind disturb parts of the atmosphere, which causes interference.
Long ago, weather forecasts were predicted using the aurora.
Countries could not agree on what they indicated though. In
Greenland they were believed to forecast storms, but elsewhere
they were believed to foretell fine weather. We now use more
sophisticated methods of forecasting weather, but the there
is some indication that the overall climate may have some
link with the amount of aurora activity.
The Earth is not alone in experiencing this light show. Aurora
have also been reported on Jupiter, it just seems a waste that no
one is able to witness it!
