For the first time ever, true north, magnetic north, and grid north have aligned in Great Britain.
The Ordnance Survey says the convergence made landfall at the village of Langton Matravers on Nov. 2. It will move through Great Britain for around three-and-a-half years.
Our calculations have discovered the three ‘norths’ will combine for the first time in history this weekđź§
True north, magnetic north and grid north will combine at a single point – starting at Langton Matravers, a village just west of Swanage #3Norths pic.twitter.com/suMMVfTEdT
— Ordnance Survey (@OrdnanceSurvey) November 2, 2022
More of a cartographical oddity than a navigational hazard, the alignment has the potential to turn Langton Matravers and other small British towns into unexpected tourist destinations for folks of a map-ish bent.
Map: Google Earth
What are the three norths?
It takes a basic understanding of cartography to understand why the convergence of the “three norths” in Great Britain is such an oddity.
True north (or geographic north) refers to the direction of the lines of longitude that meet at the North Pole. It is a fixed reference point.
Magnetic north refers to the direction a compass points (toward the Magnetic North Pole). This direction changes over time due to fluctuations in the Earth’s magnetic field.
Grid north is a quirk of cartography that happens because maps are flat but the earth is round. When creating maps meant to represent a curved surface, mapmakers indicate the single line where the flat map could touch the curved surface precisely.
True and magnetic north occasionally align along agonic lines. At these points, navigators no longer have to add an angle of declination (the difference between magnetic and true norths) when reading a compass, because that angle is zero.
What makes the latest alignment interesting is the addition of the third north — grid north.
Confused? Check out this video released by the Ordinance Survey.
A cartographical first
“It is no exaggeration to say that this is a one-off event that has never happened before,” Mark Greaves, Earth Measurement Expert at Ordnance Survey, said.
“Magnetic North moves slowly, so it is likely going to be several hundred years before this alignment comes around again.”
The alignment will have no impact on navigators, according to the Ordinance Survey.
“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,” Greaves noted. “They will always have to take account of the variation between magnetic north from a compass and grid (or true) north on a map.”
According to the Ordinance Survey, the convergence will pass out of Langton Matravers by Christmas, move through Chippenham and Birmingham, and drift over Yorkshire by August 2024. The convergence will leave the English coast at Berwick-Upon-Tweed before making landfall in Scotland in May 2026.
