Three Norths Align, And It’s Not Even Up North

Sometimes here at Hackaday we bring you stories from slightly outside our world of tech, because they have an interesting angle. Maybe they relate to science or astronomy, or in the case of the UK’s Ordnance Survey explaining how Britain’s three Norths will align, geography.

Some of you may know that the British monarch has two birthdays, but three Norths, what on earth is going on? You’ll guess that two of them are true North, pointing to the North Pole, and magnetic North, pointing to the Earth’s north magnetic field, but how about the third? It’s grid North — the north of the country’s mapping grid system in which the curved surface is projected onto a flat sheet.

It aligns with true North at 2 degrees West of Greenwich, and the news is that for the first time ever due to movement of the magnetic North Pole, the three different Norths will align at a point in the south of England. Magnetic North has been on the move at some pace over the last few decades, from a position somewhere in the Canadian Arctic islands northwards, and it so happens that for Brits its direction is briefly aligned with our view of the Pole. The Ordnance Survey story is of some interest, but for a wealth of information it’s worth consulting NASA. Take a look at the video below the break.

Header image: ArnoldReinhold, CC BY-SA 4.0.

7 thoughts on “Three Norths Align, And It’s Not Even Up North

  1. Magnetic North (while in flux over time) is at any specific time the direction to the magnetic North Pole, True North is not in flux over time, it is simply the direction to the geographic north pole, but… Grid North? It is ‘upwards’ in any map, so if you have a map of a huge area, depending on the projection, you will ususally have Grid North be equal to True North in the middle line of the map, diverging to the sides (with True North pointing slightly to the middle, while Grid North is always straight up) – the larger the area depicted in the map, the harsher the divergence. If i make a map of my front yard, the divergence of True North to Grid North cannot be shown with an inkjet printer.

    So True North and Grid North always coincide in the middle line of usual maps, so there should be a great circle on the globe (through True and Magnetic North) where any map centered anywhere on this circle would have the three coincide. At any point in history.

    1. Ah, now i get it. the great circle (which moves when the moveable of the two points defining it moves) is going throughEngland for the first time. Yay.

      As it is a Great circle, it goes through a host of other countries too, though, some of them also for the first time… So… Wha?

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