Quest For The South Magnetic Pole
Fact Sheet #8 : Magnetism on Earth
The Earth is a giant magnet. Its hot liquid centre core
contains iron, and as it moves, it creates an electric
current that causes a magnetic field around the Earth.
The Earth has a north and south magnetic pole.
These poles aren't quite lined up with the geographic
North and South Poles on a map, because the moving
inner core's poles are always wandering around.
The north magnetic pole is currently situated near
Bathurst Island in northern Canada, about 1600 km
from the North Pole. The south magnetic pole is near
the Adélie Coast on the continent of Antarctica, about 2600 km from the South
Pole. Both pole positions can wander up to 10 km per year.
Because the Earth has a field just like a magnet, it attracts things. In particular, it
will attract a small magnetised needle. A needle mounted in a case that lets it move
freely will point to the north magnetic pole. We call this needle a compass.
Using a compass in the north can give you problems. The needle is actually pointing
at the magnetic pole, which is not right at the geographic pole. So your compass
may read north, when 'north' is actually in a slightly different direction. Airplane
pilots use a compass and map which provide corrections for this 'magnetic
variation', to allow them to know which way is true north on the map. These have to
be updated every few years as magnetic north wanders away from, or towards,
actual north.
A compass needle on the surface of the Earth will point along the magnetic field
lines, towards the north magnetic pole. The needle is actually a tiny magnet, with
the north end painted red. This red end is attracted to the 'north magnetic pole'.
This means that, magnetically speaking, the north magnetic pole of the Earth is
actually a south pole! We call it the 'north' magnetic pole because it's near the
top of the Earth, or geographic north, but really it's a magnetic 'south' pole.
That's why a compass needle's north end points to it.
Source : www.worsleyschool.net