The heat from the inner core continuously reaches the outer core and collides with materials that have cooled due to plate tectonic activity. This cycle causes convection and increases a process called the geodynamo, which generates the magnetic field.
Other planets, such as Mars and Venus, lack magnetic fields in part due to the absence of plate tectonics. Based on available evidence, these planets probably once had self-sustaining geodynamos, but lost them for unknown reasons. Mercury has a weak magnetic field that is 1.1% of Earth’s magnetic field and does not provide a proper protective shield against solar radiation.
With the flow of liquid metal in the Earth’s outer core, its motion and high iron content cause the Earth to act like a giant dipole magnet with a negatively charged pole and a positively charged pole. Approximately 80% of the Earth’s magnetic field is formed in this way, but the remaining 20% is not bipolar; Rather, it consists of parallel bands of magnetic force. In some areas, this magnetic field acts like weather patterns.
The irregular patterns produce strange patches of magnetic field. Areas such as the South Atlantic Anomaly are a large strip of the Atlantic Ocean where the Earth’s magnetic field is significantly reduced. According to the researchers, the reason for the reduction of the magnetic field is the strange tectonic activities under the surface of Africa. Areas like the South Atlantic Anomaly are fascinating, but worrisome for a number of reasons.
According to Joshua Feinberg, a geologist at the University of Minnesota, the magnetosphere acts like a protective sunscreen, helping to block dangerous solar radiation from hitting Earth. In places where the magnetosphere is weak, more radiation penetrates the earth and thus increases skin cancer rates.
Another concern is the effect of solar radiation on satellites. A burst of radiation from the Sun, also called a solar coronal mass ejection, can disable satellites and other spacecraft and have devastating consequences for telecommunications, Internet access, and GPS services in the affected areas.
The South Atlas anomaly is probably 11 million years old and is related to another magnetic phenomenon known as polar reversal. The history of the Earth’s magnetic field can be traced back to ancient lava and seabed sediments. This type of rock material is rich in magnetic metal parts like small pieces of iron that rotate around the magnetic field lines.
Based on sedimentary records, scientists know that our planet’s magnetic poles shift over time. At present, the geographic North Pole is almost 500 km away from its equivalent magnetic pole (which is technically South Magnetic). According to NASA, the poles suddenly rotate approximately every 300,000 years, reversing magnetic north and south.
However, ancient geomagnetic records indicate that a complete pole reversal has not occurred for approximately 780,000 years. According to some researchers, this is because we are on the verge of turning, and the strength of the South Atlas anomaly can indicate the nearness of the next inversion.
If the poles were to reverse, the Earth’s magnetic field would likely experience a 20% reduction in strength for centuries. Such an event could disrupt current global communication systems. However, based on other researches, this reversal is not imminent.
However, studies of the planet’s interior and ancient geomagnetic records help us understand the complex interplay between the magnetosphere and life on Earth, and help us better prepare for future changes.