Auroral phenomena were observed during the time of the Greeks.
Aristotle recorded "glowing clouds" in his Meterorlogica. In
AD 37 the Roman Emperor Tiberius despatched a garrison to aid in what
he thought to be the burning port of Ostia.
The Roman philosopher Seneca
proposed that the aurorae where flames viewed through cracks in the heavenly
firmament. The French mathematician and philosopher Descartes thought
the sunlight reflected from high altitude clouds was responsible for
the aurorae.
In 1722 in was discovered that the geomagnetic field of the earth could
experience large and rapid variations. Knowledge of how and why these
variations occurred were important as ocean navigation depended on knowledge
of the Earth's magnetic field. Consequently, in 1836 the Gottingen Magnetic
Union was established by the German mathematician Karl Friedric Gauss followed
by the establishment of the British Colonial Observatories in 1840. It was not
until the Twentieth century that a more thorough understanding of this
phenomena
became available. It was at this time that a correlation between
solar activity and occurence of the aurorae became apparent.
We now know what causes these spectacular displays in the sky.
The interaction
of the
solar wind
with the
geomagnetic field of the Earth
cause energetic particles (primarily electrons and protons) to enter into the
Earth's upper atmosphere
where they interact with molecules of nitrogen and oxygen to produce the red
and green light seen in the auroral phenomena
(as seen from space,
as seen from Earth,
some recent research results).
-Revised 16 June 1999 by
cmw@ucar.edu.
Copyright 1999, NCAR.
Return to HAO homepage.
-Written by Bill Roberts-
- Approved by Paul Charbonneau -
Return to Sun Education page.
