Imagine a world with a very wacky magnetic field, the magnetic poles are not aligned at the top of the axial tilt and the sun is active enough to cause huge northern lights each night.

I know electronic systems would fail but would a compass still point at the magnetic pole or would it be rendered useless by the major solar activity?

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    $\begingroup$ @DonyorM true, but I don't expect a lot of answers are required - fairly open/closed question based in real tech. Didn't expect 100 responses $\endgroup$ – Liath Oct 22 '14 at 11:48

Yes, it would mess up your compass systems. Geomagnetic storms (which is what high solar activity is called) mess up compass navigation. These storms are what cause the auroral display to be seen at lower latitudes, and they have been proven to throw compasses off. They may not be entirely useless, but it could be thrown off by several miles.

This behavior of compasses was first noticed by Alexander von Humboldt. Humbodldt recorded compass bearings in Berlin for a year, from May 1806 to June 1807. On December 21, 1806, he noticed that his compass had become erratic during an auroral event.

Note that a stronger magnetic field would help protect against these magnetic storms.


I know I'm late to this but it needs a map.

The problem is that simple magnetic compasses are fairly approximate anyway, they don't show direction by the global magnetic field but rather by the local one. For it to be truly useful over large distances you also need a map of Magnetic Declination. An up to date map shows how wrong your compass is at your current location.Magnetic Declination (Map source is link above)

As you can see, the magnetic fields on our planet are pretty wacky even at the best of times.

It's well known that the magnetic poles move, so it's important to have an up to date map, however:

New research shows the pole moving at rapid clip—25 miles (40 kilometers) a year. http://news.nationalgeographic.com/news/2005/12/1215_051215_north_pole.html

It was previously thought to be about 10km/year.

and just to add to your troubles:

On any given day, the magnetic pole may be as much as 80 kilometers away from its average position, depending on the geomagnetic disturbances in the ionosphere and magnetosphere. http://www.scientificamerican.com/article/are-the-earths-magnetic-p/

In answer to your question, your simple magnetic compass is pretty useless without a lot more data.

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    $\begingroup$ Earth is way crazier than I thought it was ten minutes ago. That map is freaking gorgeous. $\endgroup$ – Draco18s no longer trusts SE Feb 2 '16 at 16:02
  • $\begingroup$ Not only does an up-to-date map give a figure for the magnetic-north error, it also gives a rate of change for this error. For example (hypothetical figures), the map might say that the error is +5.6 degrees as of 2010, with a rate of change of -0.3 degrees per year. This means that such a map is useful for longer than a simple point-in-time figure would allow for. $\endgroup$ – user Jul 8 '16 at 11:38
  • $\begingroup$ @MichaelKjörling, that's certainly true of Ordinance Survey maps, but in this case the map in question is the one I'm showing above and it's a tad too complex for that. $\endgroup$ – Separatrix Jul 8 '16 at 11:41
  • $\begingroup$ Absolutely true. Of course, a map showing the magnetic field of the whole planet is pretty much the source for magnetic-north error figures, if you only know how to read it (and it is reasonably up-to-date). $\endgroup$ – user Jul 8 '16 at 11:43

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