by The world is different from solar system for several reasons: It is the only planet with oxygen-breathing air, covered in liquid water and the only celestial body (capable of) sustaining life. An often-overlooked feature that makes our planet unique, however, is that it’s the only rocky body in the inner solar system with strong magnetic fields – your compass wouldn’t be useful on Mars.
But where do these poles come from, and what do they do? To answer these questions, let’s start with a trip to the center of our planet.
Earth’s core is divided into two parts: the solid inner core and the molten metal outer core. Both layers are made of a cocktail of magnetic iron and nickel, with a few dashes of lighter elements, such as oxygen, silicon and sulphur.
The inner core is extremely dense and hot, like a giant incandescent marble. But the outer core is liquid, and it’s spinning around in this solid mass itself now. It is this constant current that creates the magnetic field, John Tardunogeophysicist at the University of Rochester in New York, told Live Science.
Related: What if the magnetic field could disappear?
As the heat from the inner core continues to escape to the outer core, it encounters cooler elements through plate tectonic activity. This cycle drives convection, causing a phenomenon called a geodynamo that produces a magnetic field.
Some planets, such as Mars and Venus, do not have magnetic fields, because they lack them plate tectonics. Evidence suggests that these planets may have once existed independent geodynamos but they cry for unknown reasons. Mercury has a weak magnetic field, but still only 1.1% as solid as Earth and does little to protect the planet from the sun’s rays.
As the liquid metal in Earth’s outer core moves, its movement and high iron content cause the planet to act as a giant dipole magnet, with one negatively charged pole and one positively charged pole. About 80% of the Earth’s magnetism is organized in this way, but the remaining 20% is not dipolar; rather than forming coherent bands of magnetic energy, there are certain regions where the field rotates with eddies, behaving “like weather patterns that are kind of floating,” said Tarduno.
These unusual patterns produce unusual spots in the magnetic field – areas such as The South Atlantic Anomaly, the vast Atlantic Ocean where the Earth’s magnetic field has sunk dramatically. Researchers think this “tip” in the magnetic field It comes from unusual tectonic activity under Africa. Areas like the South Atlantic Anomaly are interesting, but also worrisome, for a few reasons.
“The magnetosphere is like a protective envelope,” Joshua Feinberg, a geologist specializing in paleomagnetism at the University of Minnesota, told Live Science. It helps deflect large amounts of the sun’s harmful rays away The world, which acts as a planetwide layer of sunscreen. In areas where the magnetosphere is weak, additional doses of radiation leak out, which can contribute to higher rates of skin cancer.
“Another concern is the impact of satellites,” Tarduno said. A burst of radiation from the sun called coronal mass ejections they can knock down satellites and other spacecraft if they are not shielded by the earth’s magnetic field. This can have detrimental effects on telecommunications, internet access and GPS services in areas of unusual influence.
The South Atlantic Anomaly may be 11 million years old, according to a 2020 paper published in the journal. PNASand can be linked to another planetary magnetic phenomenon: pole reversal.
The history of Earth’s magnetic field is recorded in ancient lava flows and deep ocean sediments. These types of rocky material are rich in magnetic metal particles, such as small pieces of iron, that move along magnetic lines. “Eventually, that original configuration is trapped in the sediments, and we get these deep-time records of how the Earth’s magnetic field was formed,” Feinberg said.
From these reports, scientists know that our planet’s magnetic poles are drifting over time. Currently, the geographic North Pole is about 310 kilometers (500 miles) away from its corresponding magnetic pole (southern magnetic technology, for now). And almost every 300,000 years, the poles suddenly turn, turning the magnet north and south, according to NASA.
However, the paleogeomagnetic record indicates a complete pole reversal it hasn’t happened in 780,000 years. Some researchers believe that this means that we have to turn around – and that the strength of the South Atlantic Anomaly could indicate that one is close.
If the poles were to move back, the magnetic field would dip to 20% stronger, perhaps for centuries. Such an event would disrupt our global communications system. However, another study shows that the flip is not close.
Either way, Feinberg said, studying our planet’s interior and paleogeomagnetic record will help us understand the complex interplay between the magnetosphere and life on Earth — and perhaps help us prepare for future changes.
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