Scientific Colloquium
May 14, 2004
The Earth's magnetic field has
always attracted much attention. Discovered
long ago, its dynamic were
uncovered only after systematic monitoring
began in the 17th Century. The
field is now precisely monitored from space
and in as many as 150
observatories worldwide. This multifaceted
phenomena, best known for
orienting needles and protecting the Earth from
the solar wind, is also an
invaluable source of information about our
dynamic planet. In this talk, I
will introduce the various sources that
contribute to the observed
magnetic field, explain how combined ground
based and satellite observations
makes it possible to isolate the field of
each source and discuss some of
the associated discoveries. Of particular
interest is the behavior of the
main magnetic field, produced within the
Earth's liquid metallic core, and
the source of most of the observed
field. The main field currently
features an intensity low within the South
Atlantic. The evolution of this
growing low could pose technological
challenges to the satellite
developers.