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Map fans are rushing to a Dorset village as all three ‘norths’ converge on one line for first time in history

The i 02/11/2022 David Parsley
The historic triple alignment of all three ‘norths”’ made landfall at the little village of Langton Matravers in Dorset on Wednesday (Photo: Ordnance Survey) © Provided by The i The historic triple alignment of all three ‘norths”’ made landfall at the little village of Langton Matravers in Dorset on Wednesday (Photo: Ordnance Survey)

A small village in Dorset has made map reading history and become the first place where true, magnetic and grid north have met at a single point.

Early on Wednesday morning mapping organisation Ordnance Survey (OS) confirmed the historic triple alignment had made landfall in Langton Matravers, near Swanage.

It will stay converged for three and a half years as it travels through different parts of the UK ending with what cartographers are calling “the special line” making its last stop in Great Britain at Fraserburgh, around July 2026.

According to OS it is the first time compasses will point to all three measures of north in history.

The event, which is being compared to a full solar eclipse, means grid north, true north and magnetic north are now forming one line from the Dorset village.

Map fans have been travelling to the precise OS grid reference of SZ 00000 76863 to point their compass needles at all three ‘norths’ at the same time and experience the once in a lifetime occurrence for themselves.

Grid north is the blue line on an OS map that either points directly to, or near to the North Pole, whereas true north is the direction of the lines of longitude that all converge at the North Pole.

Across OS maps true north varies from grid north as it reflects the curve of the earth, except on one grid north line, which aligns with longitude 2 degrees west of the zero Greenwich meridian line. Anywhere on this special line, grid north and true north align.

Magnetic north marks the northward line to the magnetic North Pole. The position of the magnetic North Pole and the direction of magnetic north moves continually due to natural changes in the Earth’s magnetic field.

After always being to the west of grid north in Great Britain the last few years have seen magnetic north move to the other side of grid north.

The change started in 2014 at the very tip of Cornwall and is slowly moving west to east across the country. It has now reached the ‘special line’ and converged with the other two ‘norths’ for the first time in mapping history.

After making landfall at Langton Matravers, the triple alignment will pass northwards through Poole by Christmas and then Chippenham and Birmingham before reaching Hebden Bridge in Yorkshire in August 2024.

It will then pass though the Pennines before leaving the English coast at Berwick-Upon-Tweed a year later in August 2025 and it does not hit land again until around May 2026 at Drums, just south of Newburgh in Scotland.

After passing through Mintlaw its last stop is Fraserburgh, around July 2026.

Mark Greaves, Earth Measurement Expert at Ordnance Survey, told i: “It is no exaggeration to say that this is a one-off event that has never happened before. Magnetic north moves slowly so it is likely going to be several hundred years before this alignment comes around again.

“This triple alignment is an interesting quirk of our national mapping and the natural geophysical processes that drive the changing magnetic field.

“But for navigators the same rules will apply whether they are simply on a trek or a walk or flying planes or navigating ships at the other end of the spectrum. They will always have to take account of the variation between magnetic north from a compass and grid (or true) north on a map.”

Map readers are taught to know the difference when navigating with a compass between magnetic north and grid north, it is also crucial for navigating in aviation and shipping.

But it would not make much of a difference to map reading for the duration of alignment, “just make it slightly easier,” Mr Greaves said.

As part of its long-running collaboration with OS, the geomagnetism team at the British Geological Survey (BGS) has made detailed measurements of the magnetic field at 40 sites around the UK.

These enable scientists to create high-resolution maps and to make accurate forecasts of the changing declination angle.

Dr Susan Macmillan, of the BGS said: “This is a once in a lifetime occurrence. Due to the unpredictability of the magnetic field on long timescales it’s not possible to say when the alignment of the three norths will happen again.”


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