THE FOUR NORTH POLES OF EARTH

1 . Geographic north pole 

It is a fixed point marking the northern tip of the axis the Earth rotates around. The geographic north pole is just one of the Earth’s four north poles, all of which have counterparts in the south.

2 . Magnetic north pole 

Get a compass out and in the northern hemisphere the needle will point to a second north pole – the magnetic north pole. This currently lies in the Arctic ocean, more than 1,000 km south of the geographic north pole. The magnetic north pole marks the northern focus of the Earth’s magnetic field, which is often shown sprouting from the north of the planet, spreading round and rejoining in the south.

The field is produced by charged particles moving in the spinning outer core of molten iron and nickel that lies 3,000km beneath the ground. Movement within the molten core makes the magnetic north pole creep around 40 km a year.

The magnetic poles of the actual Earth are not antipodal; that is, the line on which they lie does not pass through Earth’s center.

3 . Northern pole of inaccessibility 

The third north pole, known as the northern pole of inaccessibility, is an invention that is defined as the point in the Arctic ocean that is most distant from any coastline.

4 . Geomagnetic pole

And so finally to the geomagnetic pole. The Earth’s magnetic field varies from place to place on the ground because the charges that produce it are not evenly distributed throughout the outer core. But up in the stratosphere, the field begins to even out. The northern focus of the magnetic field from this high-altitude “map” marks the geomagnetic north pole. It is not a precise point, however. It measures a few kilometres across.

It is the northern end of the magnetic field that surrounds the Earth.The geomagnetic poles are antipodal points.

Why Magnetic and Geomagnetic Poles lie some distance apart?

If the Earth’s magnetic field were a perfect dipole then the field lines would be vertical to the surface at the Geomagnetic Poles, and they would coincide with the North and South magnetic poles. However, the approximation is imperfect, and so the Magnetic and Geomagnetic Poles lie some distance apart.