Our Earth is the queen of our solar system and every queen needs a shield knowing that space is a war like zone. Earth is a perfect place in space which allowed the life to flourish on it about 3.5 billion years ago. As it swings around the Sun and around its own axis it has to protect itself by the natural mechanisms which it has developed over time, after its formation. Its atmosphere saves it from meteors etc., turning most of them into ashes before they land on Earth’s surface, it also saves us from lethal UV light. The most amazing shield that it has been gifted is its magnetic field.
Imagine a giant magnetic dipole placed at the center of the Earth tilted at an angle of about 11.5 degrees with respect to its axis of rotation. Earth’s geographic North Pole(as the compass guides) is actually the imaginary bar magnet’s the South Pole because we know that a loadstone compass’s “North seeking pole” is attracted to it and “unlike” poles attract each other.
The angle between geographic North Pole and geomagnetic North Pole,changes depending upon one’s position on Earth and it also changes over a period of time. This difference doesn’t usually matters but imagine a person who is using compass to navigate, in Alaska. He really needs to know this difference otherwise he will reach the geomagnetic North Pole rather than the geographic North Pole. For this purpose, the maps there have specifically mentioned this thing. The polarities of this giant magnet are displaced over a geological time scales and at one time the reversal occurs but this process is so slow that it doesn’t affect the navigation systems etc over a smaller time scale. This variation has been traced in the rocks, thanks to paleomagnetists. This was one of the important aspects of the magnetic field – Navigation.
But how is this field formed and what makes it be called as a shield?
The solid inner core of our earth is very hot, 5700°C, just like Sun’s surface. Inner core mostly consists of iron. Then we have the outer core where molten iron, nickel, and traces of other elements are present. The inner core is solid because of high pressure (gravity) and the outer core has to face comparably less pressure and hence it is in liquid or molten form. The liquid form of this metal(iron) in the outer core allows it to move because of temperature variation, composition and density which in turn produce convection currents. The spinning motion of Earth also plays a role in this process creating whirlpools in this molten hell. Imagine an electrical generator where kinetic energy produces electrical and magnetic energy
When this hot moving iron interacts with Earth’s already formed magnetic field, there is the formation of electric currents and these currents have their own magnetic field, this process is a never ending loop and is the creator of the giant magnetic shield of earth.That is why we call this self-sustaining process as Geodynamo.
This shield is called as Magnetosphere, where the magnetic field dominates. The solar wind is material ejected from Sun primarily in form of electrons and protons. They flow towards outer regions of the solar system with speed of about 900 m/s having temperature of about 1 million degrees, we call it plasma. Imagine what damage it could possibly do to our planet. This is where “The shield” comes in to play. Imagine the shield bumping away the solar wind.
But whenever there is a powerful solar storm, solar wind disturbs Earth’s magnetic field leading to a geomagnetic storm. This storm can affect the satellites because during such a storm Earth’s atmosphere expands which increases drag for the orbiting satellites. It can also damage electrical equipment on board or present on Earth.
Auroras, sighs, this beautiful light show is formed when magnetosphere guides the charged particles from the solar wind, towards the poles where they interact with the particles present in the Earth’s atmosphere.
Scientists suspect that mars are having a solid rather than a molten core because of its weak magnetic field. This is one of the reasons why it would be dangerous to live on a planet like mars without the presence of the shield.
Magnetosphere is a savior for a planet and is truly its shield.
Featured image credits – Wiki