What is the Theory of Earth’s Magnetism?

The strength of the magnetic field of the Earth was measured by Carl Friedrich Gauss. There is a famous theory of the magnetism of Earth known as the dynamo theory.

Magnetic Field of the Earth

The magnetic field of the Earth is also known as the geomagnetic field and extends millions of kilometres into outer space. The Earth’s magnetic North pole is near the south pole, and the magnetic south pole of the Earth is near the north pole. This is the main reason why a compass works and always points to the north. The compass is actually a dipole magnet, and its north dipole is attracted to the south dipole of the Earth (the North Pole).

Earth’s magnetic field protects the planet’s atmosphere from getting eroded by solar storms. It is thought that the planet Mars also had a magnetic field at one point in its history but eventually the planet cooled too much and its inner core solidified and eliminated its magnetic field. Millions of years of erosion by charged particles emitted by the Sun will drag away the atmosphere slowly, and this is what is thought to have happened with Mars’ atmosphere.

Theory of Magnetism of Earth

There are two theories known for Earth’s magnetism:

The dynamo theory- is the most popular candidate theory for Earth’s magnetism and was proposed by Walter M. Elsasser and Edward Bullard in the mid-1900s. According to this theory, the outer core of the Earth consists of iron in a molten state and many heavy metals in a molten state. The inner core of the Earth is thought to be in a solid state because of the immense pressures on it.

Ionisation Theory– According to this theory, it is Earth’s rotation in its own axis that produces a strong electric current due to the ionisation of the outer layers of Earth’s core. This produces magnetism due to the movement of the ions. This theory is not considered a strong candidate to explain Earth’s magnetic field.

Animals that depend on the Magnetic Field

Several animals are thought to depend on the Earth’s magnetic field to navigate. Especially those animals that perform long seasonal migrations. For example, Loggerhead turtles are able to swim vast distances across featureless oceans and impeccably find their home beach of birth. It is thought that turtles have internal magnetic maps of the world’s oceans. Experiments performed at the University of North Carolina at Chapel Hill showed that the turtles could use the intensity of the Earth’s magnetic field, which is strongest near the poles and weakens along the north-south axis – to judge the latitude. The ability to sense the longitude is much more mysterious because there is no such magnetic field variation from east to west. The researchers found that recreating the magnetic conditions near a particular region of Puerto Rico made the turtles instinctively swim towards the northeast as if they were navigating towards their home beach.

Turtles seem able to use geomagnetism to determine their position on the Earth-like humans use a compass. It is now thought that all plants and animals respond to the magnetic field of our planet. In addition to turtles, even whales are thought to use the magnetic field of the Earth to locate their annual feeding and mating spots.

Creatures from bacteria to spiders to squids to sea turtles are thought to use the magnetic field to navigate their way through their lives. They find food, mates, and homes using this sense. Birds are a class apart when it comes to magnetic abilities. One study suggests that they can just open their eyes and see it the way we see the light. Biologists believe that humans once had the ability to sense the field the way other vertebrates still do. Vestiges of it are knitted into our genetic makeup, albeit dormant. But mostly, we walk around unaware of this hidden force-field that has such an effect on our lives and our world.

Magnetic Pole Reversal

The Earth’s magnetic field has not flipped once but hundreds of times in its history. Not only that, but we are long overdue for a pole reversal during our present lifetimes. Scientists are able to tell that the poles of the Earth are gathering strength to reverse once again. The electrical infrastructure built by us stands at great peril if it happens. It’s not really understood what a present-day reversal of the poles might mean for all the animals that rely on them for their daily purposes.

Conclusion

Our Earth’s magnetic field is being made even now in the core. In its turn, the Earth is continually being buffeted by the magnetic field the Sun generates within itself, which is within the one our galaxy makes. Most of the planets in our solar system make their own magnetic fields. And they are all related to the universe’s electromagnetic field, one of the fields of fluid-like substances that flow everywhere.

Our magnetic field is generated in the Earth’s entrails – it is hot yet somehow frozen solid and surrounded by a liquid metallic outer core. The heat is a remnant of the planet’s fiery birth and is thought to be the secret of the Earth’s magnetic power.

The compass and the auroras are visible proofs of the Earth’s magnetic field. For humans, this field is otherwise largely invisible. However, some animals are thought to be able to perceive it.