How are earth’s geographic and magnetic axes oriented relative to each other?

0
374
elena mozhvilo eA32JIBsSu8 unsplash
elena mozhvilo eA32JIBsSu8 unsplash

We all know that the earth’s geographic and magnetic poles are not aligned, but how much they diverge varies depending on where you live.

 The difference is caused by the way that the earth’s molten metal core spins as it cools and solidifies. 

To find out which direction your country’s geographic and magnetic axes are pointing, check this handy interactive map.

If you’re still unclear as to what I’m talking about, don’t worry — we’ll go over it in more detail below!

The North Pole​

To begin with, the geographic poles of earth’s magnetic and geomagnetic fields are located at about 70° North and South of the geographic poles.

 Much like the geographic poles, these locations do not change much over time. 

The magnetic north pole doesn’t even move much at all — a few kilometers per year, as a matter of fact. 

Since magnetic north is much closer to the North Pole, its position is usually thought of as being synonymous with that pole’s location.

However, because the precise location of the magnetic north pole does not change much over time, it’s not considered to be a true “pole.” The true geographic pole, on the other hand, does have its position constantly changing.

The Geographic Poles​

Since they are constantly changing locations, you can probably already guess that the geographical poles are not exactly the same as the magnetic poles.

 That’s because they’re defined by where earth’s spinning liquid metal core is actually pointing in space, not by where it’s pointing most of the time. 

Because of this discrepancy, some maps will show you both poles at once — sometimes labeled “Geographic” and “Magnetic.” But most maps will only show you one at a time.

 The one for your country will usually be labeled “geopolitics.”

The Magnetic Field​

Now that we’re a little clearer on how the geographic poles and magnetic poles are different, let’s look at the earth’s magnetic field. 

This is where things get a bit tricky, because there are actually two different concepts of what the definition of “magnetic north” really is. 

The first concept, which we’ve been talking about so far, refers to where the north pole of earth’s magnetic field is located. In this case, “north” would refer to where the magnetic field lines that run into northern latitudes diverge from one another — i.e., their measured position in space.

The second concept of magnetic north refers to where the magnetic field lines themselves converge — i.e. the actual location of the magnetic field’s source.

 But because we don’t know exactly where this is — we can only guess — and because it really doesn’t change much over time, we’ve never been able to get a good measurement of it anyway.

 The difference between these two measurements can be thousands of kilometers!

It might seem strange that earth’s polarity changes every single day; you certainly wouldn’t expect something like that from such a quiet planet!

 However, this change generally takes place far out in space, and has absolutely no effect on any matter that we’d encounter here on earth.

How are earth’s geographic and magnetic axes oriented relative to each other?

Facts to answer the above question :

1. Earth’s geographic and magnetic axes are pointed in the same direction in most places, but they can vary by thousands of kilometers.

2. Earth’s geographic and magnetic poles are located at approximately 70° north and south latitude; the magnetic north pole is much closer to the pole than earth’s geographic north pole.

3. It is constantly changing, the location of the geographic north pole is constantly changing; it’s not a true “pole” like magnetism’s north pole is — it’s a true “pole” only in regard to the definition we’ve used so far (and this one).

4. The magnetic and geographic poles are not in the same place in most places, because earth’s molten metal core is constantly rotating as it solidifies.

5. The difference between the geomagnetic and geographic poles exists because geomagnetism is measured relative to earth’s liquid metal core, which isn’t consistent over time.

6. True north (magnetic north) is less useful than true north (geographic north), because we never know exactly where it is, and its location doesn’t change much over time — we can only guess its position relative to our planet’s surface (which we call “true north”) based on anomalies in the magnetic field caused by local magnetism.

7. The current difference between the two norths is about 24,000 km (or 14,000 mi).

8. The direction of magnetic north shifts very slowly; it takes about 50 years for it to move one degree.

9. True north (geographic north) changes its direction between 180° and 360° every 24 hours.

10. True north (geographic north) is usually closer to the geographic than to the magnetic pole.

LEAVE A REPLY

Please enter your comment!
Please enter your name here