The magnetosphere is the immense magnetic field that surrounds the Earth. It is generated by powerful dynamic forces at the center of Earth; it protects us from erosion of the atmosphere by the solar wind, particle radiation from coronal mass ejections and cosmic rays from deep space. The forces creating a magnetic field are changing constantly. The field is continuously strengthening its wax and waning over time.
Over the past 200 years, the Earth’s magnetic field has been slowly weakening and shifting its magnetic north pole weakening and shifting its magnetic north pole. The slow shift south has quicked in recent decades, reaching a speed of 30 miles per year.
The position of Earth’s magnetic north pole was first precisely located in 1831. By more than 600 miles it has gradually drifted north-west since then. Its speed has increased from about 10 miles per year to about 34 miles per year. Navigation is affected by this gradual shift and regularly must be accounted for.
The convention of molten iron in the Earth’s core generates the magnetic field, around 1,800 miles beneath our feet. Electric currents are created by this superheated liquid that in turn produce electromagnetic fields. The process that drives pole reversal is not much understood. It is shown by the computer simulations of planetary dynamics that the reversals arise spontaneously. By observing the Sun’s magnetic field this is supported, which reverses approximately every 11 years.
At least 400 billion years ago, the Earth’s magnetic field came into existence, and the magnetic pole has reversed many times since then. Over the last 2.6 million years alone the magnetic field has switched and the most recent occurred 780,000 years ago. The scientists believe that Earth is overdue for another. But reversals are not predictable and are certainly not periodic.
Using volcanic rocks, researchers map out the ancient history of Earth’s magnetic field. The iron inside the cooled lava is magnetized in the direction of the magnetic field. Using radiometric dating techniques and investigating the rocks it is possible to reconstruct the past behavior of the Earth’s magnetism as it changed polarity or weakened, strengthened.
Scientist turns to as it strengthened, weakened or changed polarity, to track more recent magnetic changes. On these archeological artifacts carrying out measurements is challenging. The magnetism in an ancient object is very weak, which is not enough to move a needle or compass. If anything is heated and cooled many times, many magnetic patterns will be superimposed. The objects remaining in the exact location where the heating took place their reliability is dependent on. Researchers have mapped mainly modern changes in the magnetic field beneath western Europe and the Middle East despite these difficulties.
Scientists are not sure of the exact repercussions that a reversal will have. The evidence from the previous reversal is still not clear, but it may be severe. Earth is constantly attacked with a stream of charged particles from the Sun and cosmic rays, primarily protons and atomic nuclei, from deep space. The magnetic fields become weaker in the period leading up to the reversal and significantly less effectively protecting the Earth from those particles.
One of the easy ways to understand the magnetic field is to think of it as a bar magnet that has a south and north pole and runs through Earth’s center. The magnet is strong and at the surface represents roughly 75% of the Earth’s magnetic field intensity. The bar magnet is not the perfect representation. Electric currents generate the Earth’s magnetic field, but the model makes it easier to understand what is happening to Earth.
The other 25% of the magnetic field is created from another field which can be thought of as another moving bar magnet. As the central bar magnet loses the intensity, this 2nd weaker magnetic field influences Earth’s global magnetism. That is what causing the field to move in the direction it is seen moving.
Periodically locations are swap between Earth’s north and south poles, with the last flip happening about 780,000 years ago. A study in 2018 suggests that Earth’s magnetic field got weaker before the big changeover. Any kind of magnetic-field flip would still be thousands of years away and technology will be more affected.
The direct effect on humans could be slight, but not so for technology. Humans use artificial satellites for navigation, weather forecasting, tv broadcasting, environmental monitoring and all kinds of communication. These satellites could be disrupted without protecting a magnetic field by solar wind or cosmic rays colliding with electronic circuits. A weak magnetic field in the South Atlantic Ocean already adversely affects satellites and could indicate what is to come.
Deep inside the Earth, two volumes of rock are buried, each one million times larger than Mount Everest and denser and hotter than the rest of Earth’s mantle. As per scientists, these rock masses are the missing remains of Theia. The convection of molten iron interferes with them and in the South, Atlantic gives rise to the weak magnetic field.
Scientists believe that increased radiation would go along with decreased protection. However, it seems that the atmosphere would still provide sufficient protection at Earth’s surface, and animals and humans will not be significantly affected. During the moderate solar activity, all the effects currently seen during intense solar/geomagnetic storms would likely increase and occur. This includes damage to satellites or satellite outages, the ISS distortions of telecommunication and GPS signals, and increased radiation doses on long-distance aircraft.
What is geomagnetic reversal –
According to scientists, a change in a planet’s magnetic field is called geomagnetic reversal. In this, the positions of magnetic north and south are interchanged. Between the normal polarity, the Earth’s field has alternated in which the predominant direction of the field was the same as the present direction, and reverse polarity, in which it was the opposite. These periods are called Chrons.
Reversal occurrences are statistically random. There have been periods in which for several hundred years the field reversed globally, rather than complete geomagnetic reversals these events are classified as excursions. Stable polarity chrons often show rapid, large directional excursions, which occur more often than reversals.