IF Prime Minister Andy Burnham wants to clear up his apparent confusion over where the north is, he could head to Shetland around June next year.
There, just in the waters beside the island of Foula, it will become exceptionally easy to find out.
However, it may confuse him even more to learn there are three norths – geographic north, grid north and magnetic north which are predicted to be in a rare alignment for a very short time just beside Foula. This phenomenon occurs as magnetic north drifts along a line where grid and geographic north already coincide.
History has already been made after the three norths aligned in Scotland this year for the first time since records began.
It was a once-in-a-lifetime alignment that geographers had been waiting for, but it hit Aberdeenshire earlier than expected.
“It happened in Berwick-upon-Tweed, and we were waiting for it to crop up in Aberdeenshire, but it sped up a bit, and we missed it,” said geophysicist Dr William Brown of the British Geological Survey (BGS).
The “it” he is referring to is magnetic north, which wiggles around a lot because it is determined by the iron sloshing around the Earth’s core.
That is not something that is likely to trouble Burnham unless he is using a compass to find out exactly where he is in the UK. Then he would have to take into account that the north on his compass is slightly different to the north on an Ordnance Survey map, otherwise known as grid north.
This is because planet Earth is a sphere, so it has to be distorted to draw it on a 2D map. Grid north is stable, as is geographic north, which is the bit at the top of a globe.
“When people say ‘north’, they usually mean geographic north which is directly up a line of longitude towards the North Pole and down to the South Pole,” said Dr Brown. “If you were to have a globe or a map, that is the bit at the top by convention.”
There is one long line through the UK where both grid north and geographic north align. It runs from Poole on the south coast of England up to Berwick-upon-Tweed, where it then dips into the North Sea and hits land again just south of Fraserburgh. The next land mass that it goes close to, but doesn’t hit, is Foula.
Geographic and grid north always line up this way, but magnetic north has only aligned with them in the UK since November 2022, travelling upwards to reach Berwick-upon-Tweed in December last year. It was predicted to hit Drums, south of Newburgh in Aberdeenshire this October, then reach Fraserburgh around mid-December but has speeded up to leave the Scottish mainland months earlier and is now in the North Sea heading for Shetland.
“That line is moving northward because the magnetic field changes in time,” explained Dr Brown. “It’s not a static thing because it is being generated by this really dynamic mechanism within the Earth, so the field drifts a little bit in time, although it is generally quite slow. No-one needs to worry about it unless you make maps.
“From 2022 until this summer, that point where magnetic north also crosses that line of grid north and geographic north has moved from the south coast of England to the north coast of Scotland.
“That distance in four years is pretty slow for humans but fast for geology, and it’s the first time they have aligned in Scotland since records began 400 years ago.”
As the magnetic field is not predictable and does not change at a steady rate, it is now six months ahead of where it was predicted to be earlier this year.
There is also no guarantee it will keep drifting north forever.
“It happens to have drifted northward for the last 400 years or so, but it could equally slow down or stop or start moving southwards,” said Dr Brown The magnetic field of the Earth has, in fact, changed orientation in the past – leading to the magnetic north and south poles actually changing places.
“They can drift all the way round, but it is important to say that is very dramatic and something that happens over a much longer timescale,” Dr Brown said.
“The geographic poles are fixed, but the magnetic field over really long timescales can completely turn upside down, and it has done, but the last time was about 780,000 years ago. It is not something that is imminent but it is likely to happen again in the distant future.”
Conveniently for the UK, grid north and magnetic north are only a couple of degrees out and Ordnance Survey maps give guidance on how to align compasses with them. Smartphones do it automatically thanks to the models supplied by the British Geological Survey.
In other countries, the misalignment is more severe, and anyone navigating at the north or south geographic poles is advised to ditch their compass altogether as the magnetic field will send it haywire.
Due to the unpredictability of the magnetic field, scientists are unable to say when the three norths will align in Scotland once more, but believe it will be a few hundred years at least.
