﻿ magnetic field of earth

# Earth – The Magnet We Reside

(Last Updated On: August 19, 2019)

We hope you have heard of the fact that the planet we live on is itself a giant magnet and if you haven’t, this post is on that magnetic earth. Before getting you into this fact, let me give you some basic ideas on things like magnetic field which you would need to know in order to understand this astounding features exhibited by some planets like our earth .

### Magnetic field

The Magnetic field was first examined by Michael Faraday in his experiments. Magnets as we know exhibit a unique property which is the result of one of the most fundamental forces in our nature, Electromagnetic force. They have poles such as North & South. When two magnets with their north poles (Like poles) facing one another are brought towards each other it would result in a repulsion force and you’ll end up seeing two magnets repel each other. If this is the case with unlike poles (South-North) then it would be an attraction.

These magnetic fields are created with the movement of electron(s) when they are allowed to flow as free one. Consider an electron flowing along a circular path, this would result in a current flowing in the same plane but in a direction opposite to the direction of electrons (Conventional electric current). By Fleming’s rule, the electric field, magnetic field and the force all act in a direction mutually perpendicular to each other. This movement of electron produces a magnetic field perpendicular to the plane containing electric current forming magnetic loops. This is not just the case with electrons but also with ions.

You can check this by piercing a wire through a paper on which some iron fillings (iron powder) are spread uniformly. If you pass the current through the wire then you will find the iron fillings lining themselves up with the magnetic field. This is a clear indication of magnetic field present along with current.

### Layered planet

Our earth is comprised of several layers beneath the land we live on. Each layer’s temperature increases as we move deeper towards the center of the planet. The outermost surface (possibly the coolest part) which we live on is known as crust (0-100 km), mainly comprised of silica and is a perfect solid in nature. Below this is the mantle (100-2900 km) which is somewhat solid with a highly ductile nature and as a result it experiences what is known as solid state convection. In this the hotter portion of mantle which is near the core of the planet, moves up towards the crust and the cooler portion drifts down towards the core. After a while this drifted down part absorbs heat and heats up thus continuing a 500 million years cycle. This is mainly composed of aluminium, magnesium and silica. Then comes the core (2900-6370 km) which is divided into 2 regions: outer core and an inner core.

The inner core has a considerable iron content and is a dense solid as it experiences greater pressure due to the mass it encompasses. The temperature at this part is almost equal to the surface temperature of the sun (6100°C) while the outer layer is at a temperature near to 4400°C. The outer layer is liquid in nature as the pressure experienced by it is less when compared to the inner core.The outer layer comprises of iron,nickel and some light weight substances like Sulphur.

### Magnetic Earth

The outer core experiences convection similar to the one we saw in mantle but faster than that as it is a liquid. Here the cycle takes place between mantle and the inner core. On the other hand inner core region increase i.e. the volume of solid region increases because of densification of inner – outer core boundary over time due to cooling down.

During the densification process iron is trapped into the solid core being a part of its expansion but the light weight sodium forms plumes which emerge outward due to the convection current. These emerging flumes are composed of ions. These flumes raise upwards in a spiral path which can be imagined as a current flowing in a spiral due to the presence of ions. As we described in the above image, they will be engulfed by magnetic field around the spiral, perpendicular to the direction of flow of current.

These ionic loops when repeated at several parts will produce magnetic fields in different directions. All these currents and magnetic fields produced combine together in perfect way to give a resultant magnetic field which makes our earth look like a single bar magnet(Dipole) with a localized north and south poles.

### The Shield

This magnetic field around the earth extends up to an altitude of 65000 km and does the job of protecting the earth from charged particles that hits the earth from various parts of the solar system. This field is the reason why life sustains in this planet as they trap enough cosmic rays and also divert the solar storms that occur now and then. This is the reason why you could see auroras (polar lights) near the poles. But these fields are observed to be weakening and at times they would even change the earth’s north and south poles with the whole world drowning in chaos.

The disappearance of this field would result in:

• High energy particles enter the atmosphere thus ripping it out as the gases will become unstable with their contact.
• With the disappearance of atmosphere, the atmospheric pressure would drop thus vapourizing all the water molecules present in the planet which makes our condition like mars.
• It is believed that today’s mars had an atmosphere which was destroyed due to the lack of magnetic field at some moment.
• Interaction of these particles with any biological matter will result in ripping of their molecules like DNA thus resulting in unpreventable extinction.
• This would create an electronic failure all around the globe as our equipments will not be able to handle these particles without proper shielding. We have already faced a powerful solar storm in 1989,  hitting Canada which led to blackout all over the country.

Check our another article to know about Coriolis Force.

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### One thought on “Earth – The Magnet We Reside”

• March 14, 2019 at 9:24 pm