The Earth's magnetic north pole is shifting rapidly - so what will happen to the northern lights?
Science May 26, 2019 12:35 PM EDT
Like most planets in our solar system, the Earth has its own magnetic field. Thanks to its largely molten iron core, our planet is in fact a bit like a bar magnet. It has a north and south magnetic pole, separate from the geographic poles, with a field connecting the two. This field protects our planet from radiation and is responsible for creating the northern and southern lights – spectacular events that are only visible near the magnetic poles.
However, with reports that the magnetic north pole has started moving swiftly at 50km per year – and may soon be over Siberia – it has long been unclear whether the northern lights will move too. Now a new study, published in Geophysical Research Letters, has come up with an answer.
Our planetary magnetic field has many advantages. For over 2,000 years, travelers have been able to use it to navigate across the globe. Some animals even seem to be able to find their way thanks to the magnetic field. But, more importantly than that, our geomagnetic field helps protect all life on Earth.
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Earth’s magnetic field extends hundreds of thousands of kilometers out from the centre of our planet – stretching right out into interplanetary space, forming what scientists call a “magnetosphere”. This magnetosphere helps to deflect solar radiation and cosmic rays, preventing the destruction of our atmosphere. This protective magnetic bubble isn’t perfect though, and some solar matter and energy can transfer into our magnetosphere. As it is then funneled into the poles by the field, it results in the spectacular displays of the northern lights.
More:
https://www.pbs.org/newshour/science/the-earths-magnetic-north-pole-is-shifting-rapidly-so-what-will-happen-to-the-northern-lights
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I found this animation on Wikipedia, showing the difference between true (geographical) north and the direction a compass points (calle the magnetic declination or variation):
That's saying that at a line marked "10", magnetic north is 10 degrees east of true north. If you watch one place, eg the Caribbean, you can see it goes from about -5 to +10 in the 400 years shown. New York is pretty stable, between -10 and -15. London has changed a lot more - from +10 in 1590, to about -25 in 1830, and then down to -5 in 1990. It's a complex pattern.
Columbus didn't have any map for where he was going, so it didn't really matter that much to him; as long as the declination was relatively stable in each place in that year, a compass would still have done its job, ie saying where north is when the sky is cloudy. Every time you get a clear night, you can check the declination just by checking the compass against the pole star (or a clear day, if you check where the sun is when it's at its highest).
