Dec 13, 2007
Happy Birthday Kristian Birkeland
Kristian Birkeland was called the first space scientist because of his
pioneering experiments in the early 1900s. December 13, 2007, marks
his 140th birthday.
"It seems to be
a natural consequence of our points of view to assume that
the whole of space is filled with electrons and flying
electric ions of all kinds." -
Kristian Birkeland.
Kristian
Birkeland is noted for his investigation into the cause and
nature of the Earth's aurora. In 1902, he embarked on an
expedition to the Norwegian polar regions with scientific
equipment to observe, measure and record the Northern
Lights.
Based on his
observations, Birkeland hypothesized that electric currents
in the atmosphere whose source was the Sun itself powered
the aurora. On returning to the University of Oslo,
Birkeland set about testing his ideas. He built a vacuum
chamber and placed a magnetized metal ball called a terrella
inside it, representing the Earth. Birkeland electrically
charged the terrella and the chamber at varying magnitudes
and polarities and observed how the terrella behaved in its
artificial atmosphere.
Birkeland wrote:
"The magnetic
globe was then made the cathode in the vacuum-box, and
experiments were carried on under these conditions for many
years. It was in this way that there gradually appeared
experimental analogies to various cosmic phenomena, such as
zodiacal light, Saturn's rings, sun-spots and spiral
nebulae."
In 1908 and
1913, Birkeland published two volumes of his work, which
includes mathematical models and images that appeared both
to support his theories and to model aspects of comet tails,
the Sun and planetary rings. The scientific world largely
rejected his findings.
To help fund his
expeditions and research, Birkeland applied his physics to
technology and industry. In 1901, he patented an
electromagnetic gun and set up a company, Birkeland's
Firearms. After successfully constructing a 10-meter-long,
6.5-centimeter calibre cannon firing 10-kilogram iron
projectiles that "always hit their target", he planned a
version that could fire a 500 kilogram projectile at 500
meters per second, but it proved too expensive.
In 1939,
Hannes Alfvιn promoted Birkeland's ideas in his own
theory of magnetic storms and of the aurorae. In the
mid-1960s, satellites discovered magnetic disturbances in
the aurora which some scientists argued supported
Birkeland's theories. In 1973, the navy satellite
Triad detected the magnetic signatures of electric
currents in the aurora, finally vindicating Birkeland's
theory of the aurora after 65 years.
Further reading:
http://www.plasma-universe.com/index.php/Kristian_Birkeland
The Northern
Lights: The True Story of the Man Who Unlocked the Secrets
of the Aurora Borealis (2001) by
Lucy Jago
Contributed by
Ian Tresman
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