How the Earth's Magnetic Field Works: Causes, Effects, and Importance
We all know that our Earth has a magnetic field. It is because of this magnetic field that the needle of our compass points north. So how did the Earth get such a magnetic field? Besides making this compass work, what are the benefits of earth's magnetic field for us?
Composition of the Earth
So to understand how earth's magnetic field works, we need to take a look at what's inside the Earth. At the surface of the Earth is the Earth's crust, below that is the Earth's mantle, below that is the Earth's outer core, and then the inner core.
The thickness of the earth's crust is usually about 30 to 40 kilometers. The oceans we see, the mountains, and the cities we have built are all located in this crust. The diameter of our earth is about twelve thousand seven hundred and forty-two kilometers (12742 km).
So you can imagine how thin this crust is compared to this. It's like the skin of an apple. Beneath the crust of the Earth is the mantle, which is about 3,000 kilometers thick. The pressure is high here, and therefore the temperature is high. What we usually see here is a rocky and metallic composition. More than eighty percent of the entire volume of the Earth is in this part called the mantle.
Beneath the mantle is the Earth's outer core. The pressure here is very high, and therefore the temperature is also very high. That's why metals like iron and nickel here exist in a liquid state.
Beneath the Earth's outer core is the inner core. Its size is usually about 70 percent of the size of the moon. The pressure here is very high, the temperature is very high. Because of this high pressure, metals like nickel and iron exist here in a solid state. The temperature here is about 5700°C. That's the same temperature as the surface of the Sun.
How Earth's Magnetic Field Is Created
So, the liquid iron and nickel in the Earth's outer core begin to move around the Earth in eddy currents. When they move like that, they create very large electrical currents. Inside this outer core is the Earth's inner core. This is a large sphere of iron and nickel. So we all know what happens when an electric current passes around an iron sphere like this. A magnetic field is created there.
This is how the Earth got its magnetic field. And we call this the dynamo effect. So this dynamo effect is just one way to explain the Earth's magnetic field. If you search the internet, you can find a lot of other explanations for this.
So from this we can understand that we still don't have a very accurate idea of how the Earth's magnetic field was formed. Our sun is a very powerful nuclear fusion reactor. This causes very powerful solar flares to hit the Earth.
The Earth is protected by our magnetic field. Without this magnetic field, life on Earth could be completely wiped out. The special thing here is that the south pole of the Earth's magnetic field is perpendicular to the north pole of the Earth. That's why the north pole of the compass we have is tilted towards the north pole of the Earth.
Pole Reversal
But the two magnetic poles of the Earth are not always aligned like this. Scientists have discovered that once every two hundred thousand years, or once every three hundred thousand years, these two magnetic poles can completely switch. We call this a Pole Reversal.
We still don't know exactly how the two poles of Earth's magnetic field switch in this way. For this to happen, the direction of the liquid iron in the outer core would have to completely reverse. So we still haven't been able to figure out what causes this kind of thing to happen.
Last Time Pole Reversal Happened
Where two tectonic plates meet, lava has accumulated and solidified over the years. By studying the patterns in these, scientists have been able to understand that the Earth's magnetic field shifted north and south about 780,000 years ago.
So something like this could happen again at any moment. And scientists have now come to understand that the Earth's magnetic field is gradually moving away from the Earth's south pole and north pole.
When Will Pole Reversal Happen?
The strength of this earth's magnetic field decreases by approximately five percent per year. So from this we can understand that a north-south shift in the Earth's magnetic field may occur in the very near future.
Effects if Pole Reversal Happen
While a complete pole shift itself would not be directly harmful to life, the transition period could have significant effects.
The reason for this is that during the Earth's magnetic north-south rotation, the Earth is directly exposed to solar flares from the Sun. Then, it may disrupt satellite communications, power grids, and some biological systems
However, the possibility of the human race becoming completely extinct during this magnetic north-south shift is very small. Because our atmosphere can stop these solar flares to some extent. But during such a transition period, our lives will be very different from what they are now.