Modern Physics

# Earth’s Magnetic Field

The Earth’s magnetic field is important to prevent the entry of particles from the Sun and makes possible the existence of compasses.

The magnetic needle of a compass points to the geographic north, because the magnetic field generated by the needle aligns with the Earth’s magnetic field . Earth is a magnet , therefore, it produces a magnetic field.

The Earth’s magnetic field was described by the English physician William Gilbert (1544 – 1603), using the “terrella”, a spherical magnet on which a needle was supported.

What is the importance of the Earth’s magnetic field?

The Earth’s magnetic field is what makes compasses possible, used for locating in space. Thanks to this invention, thegreat sailings could happen.

The Earth’s magnetic field prevents the entry of high-speed particles from the Sun (solar wind) . Upon reaching the Earth’s magnetic field, these particles that make up the so-called solar wind are deflected because of the electrical charge they have. If they could reach the Earth’s surface, they would damage and make it impossible to communicate via radio waves, TV, internet, etc.

Formation of the Earth’s magnetic field

The dynamo theory is the most accepted for the explanation of the Earth’s magnetic field. According to this idea, iron and nickel in a state of fusion, at about 3,000 km deep, move generating electric currents that cause the magnetic field.

A magnet has a north pole and a south pole. The magnetic field generated by magnets , which is the region close to the magnet where the attraction of another magnet or materials such as iron and steel occurs, is represented as leaving the north pole and entering the south pole .

When the magnetic needle of a compass aligns with the Earth’s magnetic field, the north pole of the needle points towards the north region of the planet and the south pole of the compass magnet points towards the south region of the planet.

The attraction occurs only between different poles, that is, if the north pole of the needle points to geographic north, this means that what we call geographic north is the Earth’s magnetic south pole. Likewise, the geographic south pole of the planet must be the magnetic north pole. The image above reveals this inversion between the magnetic and geographic poles.