Fwd = "Northern and southern auroras are mirror images of each other"
- Forwarded by: fwestra@... (Frits Westra)
Original Date: Thu, 1 Nov 2001 11:02:35 -0800
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The picture of the auroras confirms a two-century-old theory.
Scientists studying the effects of solar radiation have confirmed a
two-century-old theory - the northern and southern auroras are mirror
images of each other.
Pictures taken by Nasa's polar satellite, which was launched in
February 1996 to study the effects solar energy has on the Earth's
atmosphere, prove the theory.
The northern lights - the aurora borealis - and the southern lights -
the aurora australis - are giant magnetic storms which usually occur
during the autumn and spring equinoxes caused by sudden gusts in the
The northern lights have been pondered for millenniums, but it was
only in September 1770 that the lights in both hemispheres were
recorded at the same time.
In that month, Captain James Cook saw lights in the south and Chinese
astronomers spotted similar lights in the north.
Scientists have since studied the auroras over both poles.
But because images were taken at different times they did not allow
One of the designers of the camera that took the satellite images, Dr
John Sigwarth, said they showed for the first time that auroras were
giant mirror images.
Early analysis suggested they matched on a broad scale, but some of
their fine features differed.
The gust that caused this display erupted from the enormous sunspot
9682 on October 20 and sped to Earth at about 1.6 million kilometres
Witnesses in North America said the night-time show was spectacular. .
Meanwhile, Australia and the Pacific could experience a dazzling
hailstorm of shooting stars this month as the Earth hits a series of
dense meteor trails.
Experts believe that at the storm's peak more than 20,000 meteors an
hour may be seen by observers in the western Pacific, eastern Asia and
Australia, but not New Zealand as the display will occur during our
But if the predictions are correct, the show will be awesome - a
firestorm in the heavens the like of which has not been seen for 35
The Leonid meteor shower occurs each November when the Earth ploughs
through trails of tiny dust particles left by the comet Tempel-Tuttle
as it sweeps through the inner solar system every 33 years.
Sometimes thick trails are hit, resulting in a spectacular meteor
storm as the particles - most no bigger than a grain of sand - burn up
in the atmosphere at 240,000 km/h.
This year's Leonid shower is expected to be so big it could threaten
orbiting satellites. Astronomers believe at least one satellite could
be knocked out between November 17 and 19, at the height of the meteor
Each time Tempel-Tuttle returns, it leaves a trail of shed comet
debris in a slightly different position.
�Copyright 2001, New Zealand Herald
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