What was the French
explorer Jules Dumont d’Urville doing in Hobart on
January 1 1840? Well, the South Magnetic Pole was attracting him like a magnet.
So he set sails, followed his compass South and landed on the Antarctic coast
on January 22. He didn’t quite get to the
Magnetic Pole because in these days it was still on the Continent. If he tried
again now he would get there all right because the Pole moved and is now about
200 km off shore.
The Earth magnetic
field originates from the core of our planet. The inner core is a solid sphere
of nickel and iron. All it does is radiate a huge amount of heat. The outer
core is liquid nickel and iron, and has huge electric currents spinning through
it. It looks like a magnetic coil with its North pole pointing South. On the
other side, the South pole of the magnet points North. This is why the North
end of my compass points towards the North pole. Opposite poles attract!
This huge
electromagnet is not quite aligned with the Earth rotation axis, and it is not
fixed. This is why the Magnetic Poles are not quite on the Geographic Poles,
and they keep moving. Nowadays the North Magnetic Pole is at about 388 km from
the true Pole. On the Southern side the offset is even bigger, more like 2878
km. No wonder we found this 12 or so degrees difference on the compass last
week.
South magnetic pole drift
North magnetic pole drift
While the South mag pole is rather steady, the North mag pole has gone walkabout. It used to be in Northern Canada in the 90's but it is now well on its way to Siberia. Some scientists wonder if we are not overdue for a pole shift. It has happened before, about 183 times since the Precambrian era.
Maps ref:
https://www.google.com/url?sa=i&url=https%3A%2F%2Fwww.ngdc.noaa.gov%2Fgeomag%2FGeomagneticPoles.shtml&psig=AOvVaw2cVGcGDetO_r6sU7DQQFF3&ust=1612567606503000&source=images&cd=vfe&ved=0CAIQjRxqFwoTCPiQktCw0e4CFQAAAAAdAAAAABAP
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