Since Monday, news publications across the world have been reporting that the magnetic north pole is drifting fast from the Canadian Arctic and towards Russia. What is this phenomenon about?
Two north poles
The Earth has two pairs of north and south poles. The geographic poles are defined by the axis around which the planet rotates, and are fixed. The Earth behaves like a giant bar magnet — well, almost — and this behaviour defines its magnetic north and south poles, which are not static. A compass points towards magnetic north.
The Earth’s magnetic behaviour is far more complex than that of a simple bar magnet. Its north poles and south poles move around sometimes erratically. Over large periods of time, they change their locations significantly, sometimes even interchanging their positions. The last time it so happened, with the magnetic north pole getting somewhere near where the magnetic south pole currently is, was about 780,000 years ago. But this time period is not fixed either.
The origin of Earth’s magnetism lies in its outer core, a more than 2,000-km layer of liquid iron and some other metals like nickel, that surrounds the central core, or the innermost part. This liquid iron is in constant motion due to Earth’s rotation and various other reasons, and this motion produces a magnetic field.
The magnetic north pole, or south pole, does not coincide with the geographical north or south pole. Currently, the magnetic north pole is located somewhere over northern Canada, a fact discovered in 1831 by Sir James Clark Ross. Since then the magnetic north pole has been moving across the Canadian Arctic towards Russia, and has moved hundreds of miles over the last several decades.
What is new
Scientists have now realised the pace of this movement has suddenly increased, quite significantly, from about 14-15 km per year till the 1990s to about 55 km per year in the last few years. This led to scientists on Monday updating the World Magnetic Model (WMM) that tracks this movement. It was a year ahead of schedule. Every five years, a new and updated version of the WMM is released. The last update was 2015 and the next was scheduled for end-2019. However, by early 2018, scientists realised that the faster movement of the magnetic north pole had made it so inaccurate that it was “about to exceed the acceptable limit for navigational errors”.
Why it is moving faster
This is something that scientists do not have full clarity on. The movement of liquid iron and other metals in the outer core of the Earth is known to influence the magnetic field, but this movement is chaotic and turbulent. Scientists do not fully understand how the movement happens or why. The study of the phenomena happening inside the earth can only be done indirectly or through computer modelling, because of the extremely hot temperatures prevailing there. Scientists hope that this acceleration in the shifting of magnetic north pole would throw some new insights into the phenomena happening deep inside the Earth’s surface.
The entire transportation sector, especially aviation and shipping, depends on correctly knowing the position of magnetic north to chart out their navigation paths. Similarly, it is crucial for militaries, who need to know this for firing their missiles or for other purposes. Knowing the magnetic north is vital for a number of civilian applications as well.
A standalone school compass would not be affected by this change in position of magnetic north. It will reorient itself to the new resultant magnetic north pole. But this standalone school compass is no longer used for modern requirements of navigation in aviation, shipping or military, or even in our mobile phones. This is because school compasses are not very precise as they get affected by local magnetic fields that may be present.
The compasses that are used in modern instrumentation are much more sophisticated, digital and more accurate. This is the reason why they need to be recalibrated to reflect the change in the magnetic north pole. This is what the unscheduled release of the WMM has done. It has released a set of software that will update these instruments to the new positions of the magnetic north pole.
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