The “triple alignment” makes world mapping history

The limestone cliffs of the Dorset coast just south of Langton Matravers, where the ‘Triple Alignment’ landed on November 2, 202. (Phil Champion, CC BY-SA 2.0)

The small English village of Langton Matravers, on the Dorset coast, had until recently only one small claim to fame. In 1914 a young Ian Fleming, later the author of the James Bond novels, attended Durnford Preparatory School here. Obviously he hated it. Perhaps he would have been more comfortable at one of two other prep schools in town, predictably called Spyway.

All three schools have been closed for a long time, but it doesn’t matter. On November 2, 2022, Langton Matravers snuck into another footnote in the history books. Because it is here that the “triple alignment” has made landfall in Britain.

three kinds of north

Although it looks like a sinister coalition of evildoers straight out of one of Ian Fleming’s creations, the phenomenon was not one to scare the locals – merely to delight the mapmakers. In other words, the village entered the history of cartography. The term refers to the alignment of true north, magnetic north and grid north, a first in the history of cartography and an event that may not happen again for centuries, if ever.

True North is the easiest of the three to explain. This is the direction of the current North Pole, the place where all lines of longitude converge. It is also called “geographic north”.

magnetic north is the direction your compass points. Not only is it different from true north, but it’s also moving. The position of magnetic north shifts in response to changes in the Earth’s liquid outer core. (And that has changed much more rapidly in recent years than in the previous century and a half.)

north grid is the direction of north on a flat map. Since the Earth is a globe, grid north will be slightly different from true north, except for a baseline. For maps produced by Ordnance Survey (OS), Britain’s national mapping agency, this baseline, also known as the graticule line, is two degrees west of the prime meridian of Greenwich (and east marked in blue on the map at the top of this page).

triple alignment

Three types of north, visualized. (Credit: Vermont Army National Guard)

When using a compass for navigation, it is important to know the difference between grid north and magnetic north, a difference also known as the “magnetic grid angle”. This is why many topographic maps, including those produced by the OS (but also USGS maps) show the difference between these three different norths.

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Since 2014, and for the first time since the 1660s, the orientation of magnetic north in Britain has shifted eastwards, towards the OS baseline. The north of the grid (the “graticule line”) passes through Langton Matravers. Along this line, true north and grid north are already aligned. And now, due to the movement of the magnetic north pole, the magnetic north is also aligned.

To be clear: the alignment is not a line, it is a point – the point where one line (the direction of magnetic north) intersects the other two (which are identical).

If you go to Langton Matravers now – as many map nerds have done, according to UK press reports – your compass will point to magnetic north, true north and grid north at the same time. But the second contact with the glory of the village will be brief. Because the magnetic north pole keeps moving, so will the point where it intersects with 2°W.

Slowly but inevitably this point will move north across Britain. At Christmas it will already be in Poole, about 10 miles further north. This means that at this time, and for a short while, compasses in Poole will point not only to magnetic north, but also to true north and grid north. The triple alignment will continue across England, passing through the UK’s second city of Birmingham, until it plunges back into the sea, at Berwick-upon-Tweed in the north of England, around August 2025. It will respawn in Drums, north of Aberdeen. , around May 2026 and, after a short stay in Scotland, leave the UK from Fraserburgh, also in Aberdeenshire, around July 2026.

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This is the first time in history that true magnetic north and grid north have been in “triple alignment” in the UK. Let’s qualify this: the first time in cartographic the story. The Ordnance Survey did not offer the National Grid system for its maps until 1935.

The longer the timescale, the more unpredictable the movements of the magnetic north pole. Perhaps the ‘triple alignment’ will one day return to British shores. But it could easily be centuries before that happens.

According to this map, the magnetic north pole has been moving from Canada to Russia since at least 1831. The speed of movement has increased from 15 km (about 9 mi) per year until 1990 to between 50 and 60 km (about 31 – 60 km) per year. The magnetic north pole is now actually quite close to the actual (“true”) north pole. (Credit: Visual Capitalist)

Strange Cards #1178

Many thanks to Julian Hemsted for submitting this story. To learn more, see this article in the Ordnance Survey Newsroom and watch this short video.

Got a weird card? let me know at [email protected].

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