Categories: world

Earth's magnetic north moves – here is a possible reason why

In the Hollywood blockbuster "The Core", the planet's core suddenly stops rotating, causing the Earth's magnetic field to collapse. Then the bursts of deadly microwaves make the Coliseum and melt the Golden Gate Bridge. While "almost everything in the movie is wrong," according to seismologist Justin Revenaugh of the University of Minnesota, it is true that the Earth's magnetic field protects the earth from deadly and destructive solar radiation. Without it, solar winds could crush the earth's sea and atmosphere. But the planet's magnetic field is not static. The Earth's North Magnet pole (which is not the same as the geographic north) has led scientists to something of a walking hunt in the last century. Every year it moves north with an average of about 30 miles. The magnetic north pole has moved north since the 20th century. Wikimedia Commons That movement made the world magnetic model (WMM) – which traces the field and informs compasses, GPS on smartphones and navigation systems on plan and ships – incorrect. Since the next scheduled update of the WMM did not happen until 2020, the US military requested an unusual early update to tell the magnetic north's accelerated gambol. Now, authors of a new study have gained insight into why magnetic north can move and learn to predict these shifts. Earth's Core Movement Earth's magnetic field exists due to swirling liquid nickel and iron in the planet's outer core about 1,800 miles below the surface. Anchored by northern and southern magnetic poles (which…

In the Hollywood blockbuster “The Core”, the planet’s core suddenly stops rotating, causing the Earth’s magnetic field to collapse. Then the bursts of deadly microwaves make the Coliseum and melt the Golden Gate Bridge.

While “almost everything in the movie is wrong,” according to seismologist Justin Revenaugh of the University of Minnesota, it is true that the Earth’s magnetic field protects the earth from deadly and destructive solar radiation. Without it, solar winds could crush the earth’s sea and atmosphere.

But the planet’s magnetic field is not static.

The Earth’s North Magnet pole (which is not the same as the geographic north) has led scientists to something of a walking hunt in the last century. Every year it moves north with an average of about 30 miles.

The magnetic north pole has moved north since the 20th century. Wikimedia Commons

That movement made the world magnetic model (WMM) – which traces the field and informs compasses, GPS on smartphones and navigation systems on plan and ships – incorrect. Since the next scheduled update of the WMM did not happen until 2020, the US military requested an unusual early update to tell the magnetic north’s accelerated gambol.

Now, authors of a new study have gained insight into why magnetic north can move and learn to predict these shifts.

Earth’s Core Movement

Earth’s magnetic field exists due to swirling liquid nickel and iron in the planet’s outer core about 1,800 miles below the surface. Anchored by northern and southern magnetic poles (which tend to move around and even turn every million years or so), the field grows and increases in strength, undulating based on what happens in the core.

Periodic and sometimes random changes in the distribution of the turbulent liquid metal can cause idiosyncrasies in the magnetic field. If you imagine the magnetic field as a series of rubber bands that penetrate the magnetic poles and the earth’s core, then the core is changed to different rubber bands in different places.

The geomagnetic towers then affect the migration of the magnetic pole and may even cause it to wander wildly from its present position.

Read more: Earth’s north magnet pole has moved – here is what it means for our navigation systems

A visualization of the earth’s interior, which is represented by a computer simulation. Aubert et al ./IPGP/CNRS Foot Library

So far, the prediction of these magnetic field shifts has been a challenge. But in the new study, geophysicists Julien Aubert and Christopher Finlay tried to simulate the physical conditions of the earth’s core by having supercomputers crush 4 million hours of calculations.

The researchers knew that the movement of heat from the interior of the planet can affect the magnetic field. In general, this happens at a rate of 6 miles per year. But their results revealed that sometimes there are pockets of liquid iron in the core that are much warmer and lighter than the surrounding liquid. If the difference between these hot, less thin pieces of liquid and their colder, denser counterparts is large enough, the hot liquid can rise very quickly.

The rapid movement then triggers magnetic waves that care about the core surface and cause geomagnetic jerks.

“Think of these waves as vibrating strings of a musical instrument,” said Aubert Business Insider.

Magnetic north is important for navigation models

Keeping tabs on magnetic north is absolutely essential for European and American military, as their navigation system is dependent on WMM. Commercial airlines and smartphone GPS apps are also based on the model to help pilots and users find their places and navigate accordingly.

Therefore, the British Geological Survey and the National Oceanic and Atmospheric Administration (NOAA) update the WMM every five years. The early update requested by the US military was completed on February 4.

But even with the periodic updates, geomagnetic jerks make it difficult to keep the model accurate, Aubert said.

Magnetic north is important for smartphone GPS apps. Justin Sullivan / Getty Images

His group’s new model could address this problem by helping predict how the Earth’s magnetic field can evolve.

“In the next few years, we see that it really should be possible for our groups […] to catch up with jerks and predict the future with better accuracy,” Aubert said.

Can the magnetic field ever collapse?

The Earth’s magnetic field protects its atmosphere, making “a great deal of work” holding out solar radiation, as Revenaugh put it. If we lost our magnetic field, we would eventually lose our atmosphere.

But according to Revenaugh, it is extremely unlikely to happen, because the earth’s core would never stop rotating.

Although the field collapsed, the devastating effects in “The Core” (people with pacemakers who released dead, unfortunate storm rays, uneven national landmarks) would not follow.

Without the atmosphere and magnetic field, the earth would always be bombarded by cosmic radiation. NASA

A much more likely scenario, which Revenaugh proposed, would mean that the magnetic poles were reversed as they did 780,000 years ago. When such reversals occur (there have been several in the earth’s history), the magnetic field falls to about 30% of its full strength, he said.

Although it is a far-off scenario, Revenaugh added that it is still important to improve researchers’ understanding of the magnetic field today.

“The better we can model it, the better we can understand what it is for,” he said.

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