Tell Me More About the Magnetic Pole
By Larry Newitt
Geological Survey Of Canada
Natural Resources Canada
Contrary to Captain Torvey's belief, the North Magnetic Pole is not a
magnetic meteorite floating in the polar ice. What is it then? Most of you
are familiar with a simple bar magnet. Magnetic field lines of force
leave the magnet at one end, curve around, and enter the other end. The Earth behaves somewhat like a large bar magnet. The
point where the magnetic field lines leave the Earth's surface pointing
straight up is called the South Magnetic Pole; the point where thee magnetic field
lines point straight down is the North Magnetic Pole. A compass points
approximately north because its needle orients itself parallel to the magnetic field lines
that flow between the southern and northern polar regions.
Of course the Earth's magnetic field is not produced by a simple bar
magnet at its centre. Scientists believe that it is produced by electric
currents generated by the movement of molten metal in the outer core of the
Earth. This is a complex process, resulting in two interesting
phenomena. First, the shape of the Earth's magnetic field is distorted, so
that the north and south magnetic poles are not exactly opposite each other.
The North Magnetic Pole is presently near Ellef Ringnes Island in the
Canadian arctic islands. The South Magnetic Pole is just off the coast of Antarctica,
approximately 3000 km due south of Tasmania. Second, the magnetic field is
constantly changing, and this means that the magnetic poles are constantly in
motion. In fact, since 1831 when Commander James Clark Ross first located it
on the west coast of the Boothia Peninsula, the North Magnetic Pole has
moved northwest almost 1000 km. Its current rate of motion is 15 km per
The magnetic poles also move because of distortions in the magnetic
field caused by charged particles emitted by the Sun. These emissions
result in the North Magnetic Pole moving in an irregular elliptical path
around its "normal" position. Although compasses don't work very well close
to the North Magnetic Pole, if you did have one that was functional you could
watch its needle swing over the course of a day as the Magnetic Pole moved.
It is probably this daily motion of the Pole that so intrigued and confounded
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