All of the norths are about to align over Britain
Magnetic north is on a walkabout, and your OCD will benefit
UK map lords at the Ordnance Survey have some big news for people with obsessive compulsive personality disorder or otherwise like everything to be neatly lined up.
Yes, for the "first time in history," the OS says, magnetic north, true north, and grid north are about to align over Britain.
OK, what does this mean? How many norths do we need?
True north: Not what Scots say to people from Yorkshire. Each day the Earth rotates about its axis once. The ends of the axes are the true north and south poles. True north on a map is the direction of a line of longitude which converges on the North Pole.
Magnetic north: This is what a compass points to because... magnets. This is not quite true north and is currently located (yes, it moves) over Ellesmere Island in northern Canada but is headed for Siberia. The horizontal angular difference between true and magnetic north is called magnetic variation or declination.
Grid north: The OS divides the UK into 1km squares. The vertical blue lines shown on OS maps run along grid north. The variation between magnetic and grid north is called the grid magnetic angle, which comes into play when navigating by compass and map.
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In 2014, the OS noted that for the first time in Britain since the 1660s, magnetic north would move from the west of grid north to the east and gently sweep across the country over the next decade or so.
Now these three flavors of north are due to align briefly. The OS says the alignment will make landfall at Langton Matravers, Dorset, this month and reach Poole by Christmas. By August 2024, it'll pass through Hebden Bridge and leave the English coast at Berwick-Upon-Tweed in August 2025.
In 2026, it'll hit land again at Drums in Scotland around May before making a last stop in Fraserburgh in July. There's a nice little video about the phenomenon below:
The OS says: "These predictions are likely to change (by a few months only) with the assimilation of new magnetic field observations into the model. This new data will capture the latest magnetic field signals from the geodynamo operating in the Earth's liquid outer core. Interactions between the flow of the molten iron-rich material in this region and the magnetic field generate electrical currents that, in turn, creates new magnetic flux which sustains the field.
"Energy sources for the fluid motions are primarily convection – as the Earth slowly cools down, warmer fluid rises and cooler fluid falls and solidifies onto the solid inner core. This changes the chemical composition of the fluid making it less dense, from which buoyancy forces result. The rotation of the planet also contributes to sustaining the geodynamo.
"And that will be that, for a few hundred years at least. 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."
Does it matter? No, not really – unless you absolutely must have everything neatly aligned. Maybe if you happen to live along the line, you can go outside and see how northerly north feels. ®