North pole vs magnetic North pole vs geomagnetic North pole



North pole vs magnetic North pole vs geomagnetic North pole

In: Physics

North pole = the axis the earth rotates on (north end)

Geomagnetic north pole = location of the north pole of the earths magnetic field

This pole is different than the rotational axis. Its also constantly moving. Land nav maps will include the angle difference of magnetic north from true north (called the declination).

Last time I reference the magnetic north pole was somewhere in Canada with a general heading going northeast towards Russia. It is not a straight line path.

Magnetic North Pole = the north pole of a magnet

The regular poles are set by the axis of Earth’s rotation.

The magnetic poles are set by where the Earth’s magnetic field comes out of the surface of the Earth, thus when your compass aligns to North, it’s aligning to that specific point where the Earth’s magnetic north is (on the surface).

However, the magnetic poles are not on *precisely* opposing sides of the Earth, and as a result a lot of modeling of the Earth’s magnetic field use a simplification that results in two perfectly opposing poles (i.e. the model pretends that, instead of a complex and inhomogeneous mass of really hot junk whirling around the Earth’s core, there’s just a really powerful bar magnet buried down there). These are the geomagnetic poles.

North pole: if you stuck a giant cocktail stick through the Earth, and it was spinning around on the stick, the ends would be poking out the North and South poles.

The magnetic North pole is the point on the Earth’s surface where its magnetic field is going straight down (rather than crossing the surface at a different angle, or not crossing at all). The magnetic South pole is where the field goes straight up.

The geomagnetic North pole is where the magnetic North pole would be if, instead of the Earth’s real magnetic field we pretended it had a giant bar magnet in it, and placed the magnet to get a magnetic field as close to the Earth’s actual magnetic field as possible.

[Diagram]( – the Green As are for the rotational poles; where the Earth spins. The Blue Bs are the geomagnetic poles, if we pretended there was a giant bar magnet in the middle of the Earth. The Purple Cs are the actual magnetic poles, where the magnetic fields go straight up or down.

The current South magnetic pole is probably the furthest out; it is in the ocean between Australia and Antarctica at about 64 degrees South, making it North of the Antarctic Circle, and about as far from the actual South pole as Iceland is from the North pole