Our planet has a magnetic field that performs various protective functions against the sun's ultraviolet rays. The science that studies the origin, properties and variations of this earth's magnetic field is called geomagnetism. In this post we are going to talk about geomagnetism and all its characteristics.
If you want to know more about geomagnetism, keep reading.
What is geomagnetism
Our planet has a magnetic field that can be observed from one point and has two origins: one internal and one external. Geomagnetism is the science that studies the origin, properties, and variations of the Earth's magnetic field. Magnetic poles are found at points where the dipole axis intersects with the Earth's surface. The magnetic equator is the plane perpendicular to this axis. It is a field of internal origin and is neither constant nor uniform. As time progresses, we see some rapid periodic variations, the most important of which is the one that varies with a 24-hour period. These variations are known as secular variations.
The magnetic field of external origin is primarily responsible for solar activity in the ionosphere and magnetosphere. There are other periodic oscillations such as lunar variation, annual variation, and undecadal variation. There are also some rapid variations that come from an external source, such as magnetic pulsations, magnetic bays, magnetic storms, and chromospheric effects. If you'd like to learn more about how the sun's magnetic field affects the Earth, you can read about it here. here.
Key features
When we talk about the Earth's geomagnetic field, we see that its main characteristic is that it is dipolar. This means it has two poles. On one side, we have the north pole and, on the other, the south pole. Both poles are analogous. It's like the ends of a magnet. Compasses work thanks to this magnetic field. This magnetic field is relatively weak on the planet's surface, so compasses are made by adding a lightweight magnet.
In the magnetic field, imaginary lines are produced that are mostly concentrated at the poles. The magnetic north pole is the south pole of the geomagnetic field, while the geomagnetic south pole is the north pole that is commonly known. To give you an idea, it's as if our planet had a giant magnet inside, with its ends pointing toward the poles. The direction of this hypothetical magnet isn't completely straight. Starting from the sides of the center, the bar is slightly skewed. This is known as geomagnetic declination. The difference between true north and geomagnetic north is what the compass indicates. It's a kind of angle that varies depending on our position and the weather.
As we have mentioned before, the Earth's magnetic field changes over the years. Currently, geomagnetism is studying that the Earth's magnetic field is inclined at an angle of 10 degrees with respect to the axis of rotation of the planet. We remember that the axis of rotation of the planet has an inclination of 23 degrees. If you want to know more about how the northern lights are formed related to geomagnetism, you can see more information here.
This magnetic field extends from the interior of the planet into outer space. Outside of outer space is where it meets what we call the solar wind. The solar wind is the stream of charged particles released from the sun, which are electrons, protons, and alpha particles. To better understand this process, you can read about the solar wind.
Geomagnetism at the National Geographic Institute
The main mission of the service that studies geomagnetism is to study and measure the Earth's magnetic field within each national territory. To this end, geomagnetic observatories are used to continuously record all the variables that affect the magnetic field. The data are obtained in various observatories and are processed to produce geomagnetic yearbooks. For more details on how this relates to the study of the Earth's magnetic field, you can consult this link.
Measurements are taken at repeater stations, and less frequently, densifications are made at so-called map points. Various values can be obtained to compare different points on the planet. Let's not forget that the Earth's magnetic field does not act equally everywhere. This makes it necessary to develop a type of global cartography to establish the variables that influence the change in the components of the Earth's magnetic field. The production of maps is essential to understand the conditions in specific areas, such as those subject to geomagnetic storms.
There are some places on the planet where mapping is not done. This is the case, for example, in the Canary Islands. This is due to the strong influence of their volcanic nature, which makes mapping on these scales unfeasible. The data obtained at these geomagnetic observatories are used for various research projects and collaborations with several international organizations.
Causes of geomagnetism
The origin of geomagnetism is under the Earth. As we already know, our planet has several inner layers. Scientists think that the inner core is made of solid iron and surrounded by a kind of extremely hot liquid metal. Because the flow of iron creates electrical currents, the magnetic field is generated. If you are interested in learning more about the consequences of this phenomenon, you can read about the implications of a possible change in the magnetic field in this article.
Because our planet also rotates, this heat can radiate from the core to other parts of the interior. The planet's magnetic field is made up of several superimposed magnetic fields from different sources. One origin is internal and the other is external. The internal origin is responsible for more than 90% of the magnetic field. This internal origin it is not stable but it varies over time. Variations in the Earth's magnetic field occur over very long periods of time and require updating of the models that study them.
As you can see, geomagnetism is a science that tries to study the evolution, characteristics and changes that occur on our planet with respect to the Earth's magnetic field.
Thanks for the very important information I liked it a lot since I am studying these phenomena at the moment and they were very helpful.