Earth’s magnetic field is 3.5 billion years old, and since then, it has shielded every life form on earth from the sun’s harmful cosmic radiation. The Earth’s magnetic field was studied in 1600 by William Gilbert in England. The magnetic field of the Earth’s magnetosphere is similar to a bar magnet. But the field lines are far away from Earth, and they bend away. This is due to the ionized solar wind from the Sun that encounters the earth.
Earth’s magnetosphere acts as a shield that protects it from the energetic solar wind. It extends more than five times the distance to the moon. The source of Earth’s magnetism is still not completely understood. Most investigators, however, attribute the field to convection currents within Earth’s interior. The direction and strength of Earth’s magnetic field change over time. The magnetic field can be deformed when all the other charged particles generate the electric and magnetic fields. The charged particles that are accelerated to higher energies can hit communication satellites.
What is the magnetosphere?
Plasma is ionized gas, and because the charges move, they generate currents. And those currents generate magnetic fields. The magnetosphere is the extended magnetic field that is from the earth. Then is deformed greatly through interaction with the plasma that comes from the sun. It’s called the solar wind, which deforms the earth’s magnetosphere into a long tail like a comet’s tail.
Earth’s magnetic pole is located where the magnetic field lines are perpendicular to Earth’s surface. However, it’s a complicated and rather dynamic planet because of this. The magnetic poles are not necessarily fixed at the same location. They tend to wander. Over the past few centuries, the northern magnetic pole slowly moves from Arctic Canada to northern Siberia. The magnetic field lines along Earth’s surface don’t always point to the magnetic poles. The geomagnetic poles are not currently aligned to the geographic poles.
- The major region in the magnetosphere is the Van Allen Belts. In these regions, electrons and protons are traveling at very high speeds.
So this extends outside of earth. And it affects electrically charged particles, also called ions. Magnetopause is the accidental boundary between the surrounding plasma and the magnetosphere.
Temperature: The temperature ranges are 6000 kelvin to 35,100 kelvin (10,340 to 62,720 degrees Fahrenheit). It is very hot compared to the temperatures of Earth.
Length: It extends approximately 65,000 kilometers area. The planetary distance from the magnetosphere to the solar wind pressure is called the Chapman–Ferraro distance.
Composition: It contains plasma, electrically charged particles in equal proportions of positive charge on ions and negative charge on electrons. Sun is the main source of plasma in the solar system.
Structure: Plasma, momentum, magnetic dipole, object’s spin nature, the magnitude and direction of the flow of solar wind.
What causes a magnetic field?
An electric current causes a magnetic field. There are four earth layers: the inner core, outer core, mantle, and crust. The inner and outer core is made of iron because iron is a good conductor. Iron atoms form metallic bonds where the electrons are shared between atoms and move freely in an electron sea. These moving electrons can create a magnetic field. The solid inner core heats the lower part of the liquid outer core. This causes convection currents. A hot, less dense molten mass moves upward, while a cooler, more dense mass sinks to the bottom of the outer core. These moving iron electrons generate a current, which in turn generates Earth’s magnetic field.
There’s a process on Earth called the Coriolis effect. This is what determines the major wind directions on Earth. Its directionality also controls motion deep in the Earth. In combination with the convection currents, a spiraling effect occurs. Because of this spiral, all the individual magnetic fields align and create one big magnetic field. This is why Earth has a magnetic field!
- A major difference between Earth’s magnetic field and a bar magnet’s is that the Earth’s magnetic field changes in direction over time.
How much does the Earth’s magnetic field move? A lot! The Earth’s magnetic poles flip about four to five times every million years. It’s estimated that a full pole flip only takes several thousand years. All of Earth’s past magnetic field orientations are imprinted in the Earth’s crust.
A new crust is formed at mid-ocean ridges on the seafloor, where two tectonic plates pull apart and lava wells up between them. As the lava cools, it forms tiny magnetic mineral grains. As these minerals cool, they turn into small magnets aligned with Earth’s magnetic field. This magnetic fingerprint is locked into the crust when it solidifies and can stay there for a very long time.
How does this prove that the poles flipped? People have measured the magnetism of the crust at mid-ocean ridges. And they have found that the magnetism in the rocks switches back and forth, forming a symmetrical zebra-striped pattern. Some scientists think we might see another pole reversal soon since the North pole has been wandering towards Siberia recently.
How magnetosphere is formed?
The magnetic field is generated deep down in the Earth’s core. A dynamo effect causes Earth’s magnetic field or magnetosphere. The outer core of Earth is the liquid metal, and fluid motion there generates electric currents.
- The motion of the fluid is sustained by convection and driven by buoyancy.
When the Earth spins on its axis, the electric currents form a magnetic field that extends around the planet. If the whole mass of the earth were solid, there wouldn’t be much of an electric field.
A similar example of the dynamo effect is the dynamo light on a bike. When you pedal, the bike magnets in the dynamo start spinning, therefore creating an electric current. It turns on the light. The Wang Sheeley, Arge Enlil model, shows high or lower speed solar wind coming at earth. The Geospace model is telling about magnetic variations in the vicinity of Earth. And those magnetic variations can cause geoelectric fields. Those geoelectric fields can drive currents and power lines and disrupt power grids.
Why is the magnetosphere important?
The sun is a magnet, and it also spits out charged particles that travel to the Earth as the solar wind. Now the thing is, the Earth is also a magnet. And when that solar wind arrives at the Earth, the charged particles from the sun interact with the Earth’s magnetic field.
The magnetosphere is a protective field around the earth, shielding the solar wind constantly streaming towards Earth. Typically, the solar wind is moving at about 400 kilometers per second, which is supersonic. The solar wind is primarily composed of protons and electrons-charged particles streaming out from the Sun. Some of those particles have very high energies radiation energies. And they can damage astronauts and spacecraft.
- The solar wind would blow the atmosphere away, and without an atmosphere, liquid water could not exist on the surface. So, It is the magnetosphere that protects the earth from this damage.
The radiation coming from outer space would be very damaging to any life on earth. It can cause mutations in the DNA and all sorts of bad things. So magnetosphere helps to protect it and keep the atmosphere safe.
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“Magnetospheres.” NASA Science. NASA.
Ratcliffe, John Ashworth. An Introduction to the Ionosphere and Magnetosphere. CUP Archive. ISBN 9780521083416.
“Ionosphere and magnetosphere.” Encyclopædia Britannica.
Van Allen, James Alfred. Origins of Magnetospheric Physics. Iowa City, Iowa USA: University of Iowa Press.