What's also unclear to me is how all 3 could reliably be colinear, but maybe it's an aspect of spherical geometry that eludes me.
You can draw a line between your location and the north pole, they talk about three variants:
- Magnetic North: Shortest surface line to the magnetic north pole (simply in the direction of the compass at your location).
- True North: Shortest surface line from where you are to the geographic north pole (based on the rotation axis?).
- Grid North: A line to the same geographic north pole, but aligned to the longitude lines (EDIT: for a local UK grid standard, slightly different from the global one). I didn't fully understand the subtleties of why it's different from True North, something about the projection. Not sure if it's exactly to the same north pole, the rotation axis might also change slightly and I assume that the grid north point is fixed by convention?
They are saying that there's a particular point where all three lines point in the same direction, and that point is moving.
It's a transverse mercator projection rather than a mercator as you might often see because it minimises distortion over the UK as a whole which means that the distortion is as you move away from the meridian, rather than as you move away from the equator (with a regular mercator I think all points have the grid aligned with true North)
This grid is setup such that it's origin is not on the prime meridian (at Greenwich), but 2deg west so only points on the line 2deg west are aligned with true north.
If grid north and true north are the same everywhere, it would be proof the entire Earth is flat.
The magnetic north wanders around, and it now happens to match along the 2° meridian.
But really the article is a year early, as the alignment point should make a brief landfall in Scotland late next year (which the article acknowledges later on). Or perhaps they expect Scotland to secede before that.
oersted•1h ago
Love that, sounds like something Douglas Adams or Terry Pratchett would write :)
rwmj•19m ago