The US National Centers for Environmental Information (NCEI) and the British Geological Survey (BGS) released an update version of the World Magnetic Model (WMM) on Tuesday, officially updating the position of magnetic north pole and predicting how the Earth’s magnetic field will shift and change over the next five years, reports Live Science.
The WMM predicts the difference between the geographical true north and magnetic north, an ever-changing point in the Northern Hemisphere where Earth’s magnetic field lines point directly into the planet. Knowing the difference is integral to satellite and aircraft navigation, as well as the GPS used by apps like Google Maps that we all use every day. The model combines data from satellites and high-precision magnetometers at ground-based observatories to predict the magnetic field at each point on Earth, and requires consistent updates to remain accurate.
This latest update is part of the regular five-year schedule and most of us won’t notice anything different as a result. It is simply part of keeping navigational systems functioning and improving future predictions about the Earth’s magnetic field.
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Our planet’s magnetic field is generated by an outer core of molten iron some 2,850 to 5,000 kilometres below the surface. The constant motion of this electrically conductive material produces an electric current when it moves through an existing weak magnetic field. The current in turn generates its own magnetic field, creating a self-sustaining system known as geodynamo.
The dynamism of the system, key to preserving Earth’s magnetic field for billions of years, is why the WMM requires regular updates. Where geographic north is a fixed point, magnetic north is constantly in flux, shifting tens of miles per year. “The real challenge is, and the reason why we release a model every five years, [the magnetic field] doesn’t change in a regular way. It’s not completely predictable. It’s a really complicated chaotic system,” William Brown, a BGS geophysicist who helped create and update the WMM, told Live Science. Without regular updates – including some off-year ones like in 2019 – navigation could go wildly astray.
Take, for example, a certain North Pole-based delivery man, known for his distinctive red suit. According to BGS, should he travel from South Africa to a snow-covered roof in the UK using the previous WMM and be just one degree off-course, the journey of around 8,500 kilometres would end up a whopping 150 kilometres from the intended destination – that would be like aiming for Macao and ending up in Zhaoqing!
