The magnetic north pole is moving...

[Old Bumbulum]

Lets face it, science will always have egg on its face over the electron débâcle.

Do tell, I suspect most of us can't face this as we've no idea what it is!

 

[RichardS]

Do tell, I suspect most of us can't face this as we've no idea what it is!

+ve and -ve vs directional flow of electrons, one assumes.

Richard

 

[Lon nan Gruagach]

Do tell, I suspect most of us can't face this as we've no idea what it is!

Before anyone ever actually got hold of something and said "hey guys, this is the wotsit that does all the electrickery stuff" and called it an electron, the + and - of electricity had already been defined. The guess at the time was that there was some particle involved that had a + charge and flowed from + to -.
Trouble is that electrons have a - charge and flow the wrong way.

 

[KINGFISHER 8]

The Earth's off its axis! - We're doomed! … DOOMED!

Don't panic! Don't panic! ………. :encouragement:

 

[dolabriform]

The Earth's off its axis! - We're doomed! … DOOMED!

Don't panic! Don't panic! ………. :encouragement:

I'll get me towell and stick out my thumb :encouragement:

 

[Lon nan Gruagach]

Although I'm not sure why you're quoting me rather than AntarcticPilot .... I was the one who ended my post with a smiley.

Richard

And thats exactly why I quoted you in a post that ended with polar bears and penguins.

 

[[3889]]

This thread reminds me strongly of a time when I was an undergraduate on an expedition to Spitzbergen. Six of the party were geologists, and four weren't. Our camp had an excellent view of some highly deformed rocks, and one evening we were discussing the processes that had given rise to the deformation. This was when plate tectonics was a new and exciting idea, and we were speaking of continents colliding and rocks being squeezed and crushed. One of the non-geologists listened with big, round eyes, and eventually remarked ".Gee, it must have been real exciting round here when all that was happening!"

We geologists looked at each other, and then one of us quietly asked "How long do you think it all took?" - of course, the events we had been discussing took tens or hundreds of millions of years, with the change even over a lifetime being imperceptible!

Yes, we expect the magnetic pole to flip from the present polarity to the opposite sometime, but the change will happen at rates comparable to the existing rates of change. There may be a period when the magnetic field is weak, but it won't be nothing. And the change will be slow enough that we will simply adapt, just as we adapt to the variation of the compass at present.

Certainly it is nothing to worry about!

Are you sure? The resolution of indicators of past magnetic inversions are nowhere near sufficiently precise to define a timescale in terms of millennial, decadal, annual or even instantaneous shifting. The term "geological timescale" is misleading: the K/Pg impact, which was certainly a geological event, was over in less than an hour.

 

[AntarcticPilot]

Are you sure? The resolution of indicators of past magnetic inversions are nowhere near sufficiently precise to define a timescale in terms of millennial, decadal, annual or even instantaneous shifting. The term "geological timescale" is misleading: the K/Pg impact, which was certainly a geological event, was over in less than an hour.

It depends what you are looking at. The estimates I gave ARE estimates; you are right to say that there is no record of magnetic change that is of high enough resolution or continuity to track how rapidly the change occurs. That said, there are potential datable sequences that have the potential to provide such continuity and resolution. The obvious one is polar ice cores; they can provide data at an annual resolution with high continuity over very long periods (The longest datable ice core extends to about 720,000 years ago). At least one event (see https://en.wikipedia.org/wiki/Laschamp_event) is within that period, and has been dated quite closely - the period of reversal lasted about 440 years, and the transition took about 250 years. Another candiate would be varve sequences; the problem there is that they depend on very specific conditions for their formation and these conditions tend to be ephemeral. A varve sequence may be hundreds of years long, but of course geological time is such that having a varve sequence that spans an interesting event is unlikely.

 

[cpedw]

the period of reversal lasted about 440 years, and the transition took about 250 years.

Does that mean the North Mag Pole meandered south but then went back north without really hanging about down south?

Derek

 

[AntarcticPilot]

Does that mean the North Mag Pole meandered south but then went back north without really hanging about down south?

Derek

That's exactly what it means. Short-lived events like this (called excursions) are known from the record.

 

[NickCharman]

GPS does show direction, too.

Although an old post ... You miss the point of GPS cog. Cog is what average course the GPS aerial Has Been steering recently. The compass shows the direction of the ships head. Both are useful but different. You cannot steer by cog. You will always be chasing a historic path. A well damped compass is much better for the helm to steer by.

 

[RichardS]

You cannot steer by cog.

I've never looked at my compass in 11 years of sailing ..... and have always arrived at my chosen destination without ever hitting anything ..... other than the sand.

Richard

 

[Spirit (of Glenans)]

Thanks, but 50km is only 0.7 degrees where i am in the UK so not that significant to me.

Www.solocoastalsailing.co.uk

But if your chart is ten years old, the variation would be seven degrees.
I assume the accelleration of polar movement was not noticed until relatively recently and the variation predicted on older charts is now out of date. The main learning from this discussion is that if, like me, you prefer paper charts, it's time to buy new ones.

 

[Spirit (of Glenans)]

Oops... good spot Norman. Thanks!

This was before the last polar flip.

 

[Spirit (of Glenans)]

Copy them on to transparent paper and flip them vertically?

But perhaps the North pointing end of a compass is actually a magnetic South pole and we only call it North because that's the way it points.

Richard

My old science teacher taught me that the pole marked "N" on a magnet was correctly called the " North-Seeking Pole."

 

[cpedw]

If I might drift this thread a bit ...
When the pole starts to head south, will there be a better chance of spotting Aurora from home? I write as a disappointed Hurtigruten traveller who spent a lot to see a lot of rain and mist in the fjords. Until last month, I could get plenty of that here in Oban.

Derek

 

[NickCharman]

I've never looked at my compass in 11 years of sailing ..... and have always arrived at my chosen destination without ever hitting anything ..... other than the sand.

Richard

I do not doubt you.
The problem is that the cog is telling you what course you have recently been averaging. Not where the ship is now pointing. So the helm that corrects for past average course is working behind the curve. So you will be unlikely to steer as efficient and straight course as with a compass.
Also not using the compass to compare actual heading and achieved course will mean you have no idea of leeway or tidal effects. GPS failure or the ships electrical supply failure aside.
Anyway knowing compass variation and deviation as is relevant to this threads main issue is of concern to the navigator.

 

[bbg]

Does this mean Santa and his elves will have to move too?

Not just Santa and the Elves. Polar bears and penguins will have to switch places.

 

[AntarcticPilot]

But if your chart is ten years old, the variation would be seven degrees.
I assume the accelleration of polar movement was not noticed until relatively recently and the variation predicted on older charts is now out of date. The main learning from this discussion is that if, like me, you prefer paper charts, it's time to buy new ones.

Don't worry. There are TWO magnetic North Poles! There is the Dip Pole, which is where the Earth's magnetic field lines are vertical and there's the Geomagnetic Pole, which is the pole of the average magnetic field of the Earth. The latter is what compasses point to (to a first approximation; it gets more complicated!). The Dip Pole (or North Magnetic Pole) is the one that's moving; the North Geomagnetic Pole (to which compasses point) is moving much slower, and the data on charts is still perfectly valid.

 

[Mudisox]

I was always taught and continued to teach that navigational fixes were always historical. A DR or Ep is really what you need. Even GPS is second behind. ..........Not that I like second behinds