THE magnetic poles – In whose direction they point the magnetic needles of all the knots on the earth’s surface – and the geographical ones – which correspond to the intersection of the terrestrial rotation axis with the surface of our planet – do not coincide with each other And, even more important, the position of the magnetic poles changes continuously over timewhile that of the geographical poles is fixed. Since the beginning of its measurement in the 19th century, the North Magnetic Pole is migrating from the north of Canada to Siberia. Based on the models of the most advanced terrestrial magnetic field at our disposal, the current position of the North Magnetic Pole is 72.76 ° of West Longitude And 80.85 ° north geodetic latitudejust under 1000 km from the north geographical pole. The south magnetic pole, on the other hand, is located in the coordinates 107.24 ° and of longitude And 80.85 ° S of geodetic latitudenot far from the coast of Antarctica in the direction of Australia. The axis that connects these two points, called Dipolar magnetic axistherefore it is found misaligned by the rotation axis of our planet of about 9th.
The Earth’s magnetic field has undergone drastic variations, including 183 Inversions of the magnetic poles in the last 83 million years. This event sees the exchange between the North Pole and South Magnetic, with the lines of the field that turn upside down: a compass, the first episode to the north, would thus indicate the former southern magnetic pole.
The rhythm that the magnetic poles move is impressive. From its first location in 1831the North Magnetic Pole not only moved from Canada to Siberia, but did it at an ever increasing rhythm, From about 10 km per year about 50 km from the year. In the last 5 years it seems to have slowed down again, moving to about 35 km per year towards Siberia. The reason for this deceleration is still the subject of study and some researchers connect it to the non -uniform decrease in the last two hundred years of the magnetic field intensity, which is weaker near Canada and more strengthened near Siberia, thus moving the position of the North Pole towards the latter area.
The reason for this dramatic change has to do with theorigin same as the magnetic field. The latter is generated in the depth of the earthmore precisely in external nucleus. This area, about the thickness of about 2300 km and temperatures of the order of 3500 ° Cconsists of a fluid of iron and nickel which behaves like a sort of dynamo able to generate a Dipolar magnetic field Starting from the movement of the rich iron melted rock, which is electrified. The complex movements of this electrified fluid make the Various earth magnetic field over timeincluding its poles, which are conventionally defined as the points on the earth’s surface in which the Magnetic field lines are perpendicular to the surface same. Being a dynamic mass in continuous movement, such will also be the position of the poles.
Thanks to the study of terrestrial subsoil champions, scientists are able to determine the Directorate of the magnetic field terrestrial during the history of the earth, since the subsoil is equipped with ferromagnetic materials in which the effect of the management of the magnetic field remains imprinted as a sort of footprint in the ground. This realized that the Earth’s magnetic field has changed dramatically in the past, to the point that many times during the history of our planet there has been a reversal of the magnetic poles (183 Inversions in the last 83 million years). This phenomenon consists of an exchange of the north magnetic pole with the south and vice versa, with a variation of the lines of the magnetic field that are reversed. With a compass we would notice like the needle, which first pointed “to the north”, now would aim “to the south” (that is, towards the former southern magnetic pole).
Some scientists suppose that the weakening of the magnetic field seen in the last 200 years could prelude to one future reversal of the magnetic fieldwhose exact date of forecast is almost impossible with current knowledge. We often hear about such an event with catastrophic tones and this has to do with the fact that, during a reversal, the earth’s magnetic field reorganizes himself, decreasing his intensity. Since the Earth’s magnetic field is it shield which allows biological life to survive the intense ionizing radiation from space, its weakening would be dangerous for all living beings.
Therefore, constantly monitor the Earth’s magnetic field and model its behavior is of fundamental importance, not only for biological life, but also for everyday activities. Knowing how the poles move is essential for example to provide careful positions on the earth’s surface by GPS systems, used by ships, planes and for military and scientific purposes.
