Know Geology…
Earth’s Magnetic Field
Earth is surrounded by Magnetic Field.. Let’s understand it…
We live on the planet Earth. The Earth is our provider of all of our needs. As we all know, there are various sources of radiation present on the Earth, such as Uranium, etc. There is also cosmic radiation surrounding us, although the intensity of the radiation is so low that it cannot directly harm us. However, there is a massive amount of radiation in the vast expanse of the universe. Even the Sun emits powerful ultraviolet radiation, which is able to cause fatal cancer like illnesses. Then why is this radiation not able to harm us? The answer lies with the Earth’s magnetic field.
How magnetic field is generated?
When the Earth was formed around 4.5 billion years ago, she was a hot ball of molten rocks. As the time passed, the Earth’s interior segregated into 3 parts: crust, mantle and core. This core is made of iron and nickel. The core can be divided into outer core and inner core. The outer core is hot, and therefore in liquid state, while the inner core is also hot, but in solid state due to the pressure from surrounding crust, mantle and outer core. Still, the iron particles present in the inner core are constantly moving. When the iron particles on the surface of the inner core get relatively cooler than the particles inside the inner core, they get denser, and move towards the center of the inner core. At the same time, the relatively warmer and lighter iron particles from the interior of the inner core tend to move towards its surface. This movement of the iron particles creates electric currents in the inner core, and the currents are formed inside the inner core. These currents are called as ‘Convection Currents’. The electric currents, combined with the magnetic properties of the iron particles, generate the Earth’s magnetic field, or the magnetosphere.
Aurora
When the solar winds reach the Earth, they interact with the Earth’s magnetic field, and the interaction causes a glow in the atmosphere. This event is called as ‘aurora’. Generally, due to the bipolar nature of the magnetic field, aurora is only visible in the north and south poles. But when the solar activity is intense, the aurora will move away from the poles, and may be visible even at lower latitudes. An excellent example of this activity was observed on April 22 and 23, 2023, when the solar activity was so intense that the aurora was visible in Ladakh in northern India.
Effects of Magnetic Field
This magnetic field protects the Earth and her inhabitants from harmful cosmic radiation. However, this magnetic field is not completely invincible. In case of strong cosmic activity, the high solar winds can disturb the magnetic field, and geomagnetic storms can penetrate the Earth’s magnetosphere. This can result in the widespread radio and power blackouts. During the greatest solar storm ever recorded, known as the ‘Carrington Event’ in 1859, the solar activity was so intense that the northern aurora moved down to Hawaii and Cuba, while the southern aurora moved up to Santiago, capitol of Chile. This event caused severe disruption of telecommunication around the world, as the telegraph poles were fried and communication was stopped. Similar event took place in 1989, plunging the province of Quebec, Canada into 12 hours of electrical blackout.
Due to this magnetic field, there are charged particles trapped in the atmosphere. The area where the charged particles lie is called as the ‘Van Allen Belt’. The Van Allen Belt is supposed to be uniform around the Earth, but that is not the case. In some places, the Van Allen Belt has come closer to the Earth’s surface. In these areas, conflict between the Van Allen Belt and the Earth’s magnetosphere results in the reduction of the Earth’s magnetic field. In the southern Atlantic Ocean, there is such an area, where the strength of the Earth’s magnetic field is significantly lower than that of the rest of the Earth. This anomaly known as the ‘South Atlantic Anomaly’. Apart from the interaction with Van Allen Belt, there are few other factors, which play a crucial role in the reduction of the magnetic field. These factors include global warming, climate change, use of chlorofluorocarbons, etc. Without the magnetic field, the powerful solar winds would blow away the Earth’s atmosphere, and cause fatal cancer like illnesses on the Earth. The Earth as we know her would not exist, and instead a desolate planet would remain behind, should the Earth’s magnetic field vanish.
-Ninad Bhagwat
MTU, USA
