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Why Does Earth Have Magnetic Poles?

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Why Does Earth Have Magnetic Poles?

Written by Joanna Thompson

Earth is the only rocky body in the inner solar system with strong magnetic poles. But where do these poles come from, and what do they do?

Earth is unique in the solar system for a number of reasons: It’s the only planet with a breathable oxygen atmosphere, it’s covered in liquid water and it’s the only celestial body (that we know of) to harbor life.

An often-overlooked characteristic that makes our planet special, however, is that it’s the only rocky body in the inner solar system with strong magnetic poles  — your compass would be useless on Mars.

But where do these poles come from, and what do they do? To answer these questions, let’s start with a journey to the center of our planet.

Earth’s core is separated into two layers: 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 sulfur.

The inner core is extremely dense and hot, like a giant incandescent marble. But the outer core is fluid, and it swirls around this solid mass with its own convective current. It’s this constant convection that generates Earth’s magnetic field, John Tarduno, a geophysicist at the University of Rochester in New York, told Live Science.

As heat from the inner core continuously radiates into the outer core, it meets material cooled by plate tectonic activity. This cycle drives convection, giving rise to the so-called geodynamo that produces the magnetic field.

Other planets, like Mars and Venus, don’t have magnetic fields, in part because they lack plate tectonics. Evidence suggests that these planets may have once had self-sustaining geodynamos but that they petered out for unknown reasons.

Mercury does have a weak magnetic field, but it is only 1.1% as strong as Earth’s and doesn’t do much to shield the planet from solar radiation.

As the liquid metal in Earth’s outer core flows, its motion and high iron content cause the planet to act like a huge dipolar magnet, with one negatively charged pole and one positively charged pole.

Around 80 percent of Earth’s magnetic field is organized this way, but the remaining 20% is non-dipolar; rather than forming parallel bands of magnetic force, there are certain regions where the field swirls and eddies, behaving “like weather patterns that kind of float around,” Tarduno said.

These irregular patterns produce weird patches in the magnetic field — places like the South Atlantic Anomaly, a large swath of the Atlantic Ocean where the intensity of Earth’s magnetosphere dips dramatically.

Researchers think this “dent” in the magnetic field arises from unusual tectonic activity underneath Africa. Areas like the South Atlantic Anomaly are fascinating, but they are also concerning, for a couple of reasons.

“The magnetosphere is like a protective envelope,” Joshua Feinberg, a geologist who specializes in paleomagnetism at the University of Minnesota, told Live Science. It helps to deflect huge amounts of dangerous solar radiation away from Earth, acting like a planetwide layer of sunscreen.

In areas where the magnetosphere is weak, extra doses of radiation leak through, potentially contributing to higher rates of skin cancer.

“Another concern is the effect on satellites,” Tarduno said. Bursts of radiation from the sun  called coronal mass ejections can knock out satellites and other spacecraft if they aren’t shielded by Earth’s magnetic field.

This can have catastrophic effects for telecommunications, internet access and GPS services in anomaly-impacted areas.

The South Atlantic Anomaly may be 11 million years old, according to a 2020 paper published in the journal PNAS,  and it might be connected to another planetary magnetic-field phenomenon: pole reversal.

The history of Earth’s magnetic field is written in ancient lava flows and deep-sea sediments. These types of rocky material are rich in magnetic metal fragments, such as tiny chips of iron, which orient themselves along magnetic-field lines. “Eventually, that original alignment gets locked into the sediments, and we get these deep-time records of how the Earth’s magnetic field was oriented,” Feinberg said.

From these records, scientists know that our planet’s magnetic poles drift over time. Currently, the geographic North Pole is about 310 miles (500 kilometers) away from its corresponding magnetic pole (which is technically magnetic south, at the moment).

And roughly every 300,000 years, the poles suddenly flip, reversing magnetic north and south, according to NASA.

However, the paleogeomagnetic record shows that a complete pole reversal hasn’t happened in about 780,000 years. Some researchers believe this means that we’re due for a flip — and that the strength of the South Atlantic Anomaly could indicate that one is close.

If the poles were to reverse, Earth’s magnetic field would dip to 20 percent strength, possibly for centuries. Such an event would plunge our current global communications system into disarray. However, other studies suggest that a flip is not imminent.

Either way, Feinberg said, studying our planet’s interior and the paleogeomagnetic record will help us understand the complex interplay between the magnetosphere and life on Earth — and possibly help us prepare for future change.

8 COMMENTS

  1. If the poles were to reverse, Earth’s magnetic field would dip to 20 percent strength, possibly for centuries.

    The poles do not “reverse” as such. There is “up” or “down”. It is just a magnetic field generated bu interaction with the sun’s electromagnetic fields. And it is capable of changing, which is why true north and magnetic north are not on the same axis.

    Changes to the alignment of the magnetic field would require essentially flipping the earth, not the magnetic poles. So it is not going to happen in a split second, but gradually over a log period of time. As stated reversal time varies wildly, with the last one happening about 780,000 years ago, and an average reversal period of 300,000 years, but since no-one was taking notes back then, it is all theory. And a flip will not happen overnight.

    A polar shift will not happen in anyone’s lifetime. And a polar shift per se will probably not disrupt communications, as radio travels through ‘warp fluid’ commonly known as the ether.

    Polar reversal might happen over 5000 generations, so no big changes. It is not like you are going to wake up tomorrow morning and find it has reversed. There is evidence it has happened before, such as discovery that Antarctica was once NOT the coldest place, being green and lush. Why? because it was once not due south. Perhaps it was the equator.

    It will not happen over night. And we know that it is happening all the time, because magnetic north is continually moving. The idea of an overnight flip is just fear mongering.

    It is just like the Greens saying that all the ice in Antarctica could suddenly slide off the Antarctic land mass, drop into the ocean, raise the water level, and drown the earth. Or the earth’s angle of inclination could change over 100,000 years (5000 generations) and the Shara Desert could be the new Antarctic, and the Antarctic become a new tropical oasis. 1500 generations ago, you could walk from New Guinea to Australia.

    The idea of an overnight flip is just fear mongering.

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  2. The earth has already lost over 20 percent of its mag field since the Carrington event in 1859 during solar cycle 10, there has been changes to all the planets in our solar system recently, because its the sun that causes all these things during its different cycles, if anyone doubts that, ask yourself where you would be without it?
    The current obsession with CO2 is bad science, renaming their bugaboo Carbon pollution is telling in that we are all made of Carbon which is different than CO2, every body breaths out a kilo of carbon dioxide every day, you are the Carbon they want to get rid off.
    Hence the depopulation agenda of the UN 2030 and the WEF, their stated goal is reduction of populations world wide too 500 million, don’t believe me then read the documents they aren’t shy about publishing.
    No questions to the Politian’s about that during debates or press events I see, they are all pushing this bullshit on us, all the main party’s are complicit in this crime against humanity.
    Covid is just the beginning

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  3. The Poles should fuck off back to Warsaw IMHO.
    Clown World 2023, The EU are going to impose strict higher taxes on Chinese electric vehicles because the little yellow bastards are producing to many of them, FFS what happened to the mantra “more and more producers worldwide will make millions of EVs and the price will drop substantially” ? the Chinese are doing exactly that and are going to be sanctioned for it, FFFUUCCK, Western leadership are suffering some type of a moronic catchy virus that forces them to do stupid stuff.

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