'Vigorous' magnetic field oddity spotted over South Atlantic

An illustration of Earth's magnetic field.
(Image credit: Shutterstock)

A long-standing weak spot in Earth's magnetic field is getting weirder, and it may be splitting into two distinct zones of weakness. 

The South Atlantic Anomaly is a section of Earth's magnetic field between Africa and South America. For decades at least, this region of the magnetic field has gotten weaker and weaker, part of a global trend. According to the European Space Agency (ESA), the global magnetic field has lost 9% of its strength over the past 200 years. The South Atlantic Anomaly seems to be a particular point of change. Now, satellites investigating the anomaly have detected an intensified weakening southwest of Africa, suggesting that the anomaly could split into two separate low points. 

This change wouldn't signal any imminent danger, but it might help reveal what's going on in the Earth's core to drive the changes, according to the ESA. The agency's satellites are gathering data on the electromagnetic field to answer this question. 

Related: What if Earth's magnetic field disappeared?

Fluctuating field

The magnetic field is why compasses and GPS work, and it protects the planet from charged solar particles that can damage electrical equipment. For that reason, its fluctuations are important. But they are also poorly understood. The Earth's magnetic field arises from the churn of the planet's liquid iron core, which acts like an enormous magnet (thus, the North and South poles). But the magnetic field isn't as neat and tidy as the one created by a typical bar magnet. It has areas of strength and weakness, and sometimes the field even flip-flops, with north and south switching places. 

The current weakening of the Earth's magnetic field could portend another one of these flip-flops, or it could simply be a temporary fluctuation. If the field does reverse, the South Atlantic Anomaly is likely to be the origin of the change, research has found.

The ESA's Swarm constellation of satellites, launched in 2013, is probing the anomaly for small changes that could explain what's going on in the core. Since the group of satellites went into orbit, the South Atlantic Anomaly has developed a second center of minimum magnetic intensity, according to the ESA. This second weak spot indicates a complex process in the Earth's core; a simple dipolar, north-south magnetic field can't explain the pattern, the agency reported in a press release. 

Mystery below

"The new, eastern minimum of the South Atlantic Anomaly has appeared over the last decade and in recent years is developing vigorously," Jürgen Matzka, a geomagnetism researcher at the GFZ German Research Centre for Geosciences, said in a statement. "We are very lucky to have the Swarm satellites in orbit to investigate the development of the South Atlantic Anomaly. The challenge now is to understand the processes in Earth's core driving these changes."

The field is weak enough to sometimes affect satellites that pass over the region, according to the ESA. Unprotected from space radiation, the International Space Station and other satellites in low-Earth orbit sometimes experience "single event upsets" in which communications are disrupted or computers go on the fritz. Astronauts sometimes see sudden white flashes from a burst of radiation in front of their eyes. 

"This is a well-known area where all different types of satellites — not just a space station with people, but normal communication satellites and others — have problems," former astronaut Terry Virts told the BBC in 2018. "You want to kind of get through there as fast as you can on the way to the moon, or wherever you're going."

Originally published on Live Science.  

OFFER: Save 45% on 'How It Works' 'All About Space' and 'All About History'!

<a href="https://www.livescience.com/download-your-favorite-magazines.html" data-link-merchant="livescience.com"" target="_blank">OFFER: Save 45% on 'How It Works' 'All About Space' and 'All About History'!

For a limited time, you can take out a digital subscription to any of <a href="https://www.livescience.com/download-your-favorite-magazines.html" data-link-merchant="livescience.com"" data-link-merchant="livescience.com"" target="_blank">our best-selling science magazines for just $2.38 per month, or 45% off the standard price for the first three months.

Stephanie Pappas
Live Science Contributor

Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz. 

  • Bob Sizemore
    The article states, "The magnetic field is why compasses and GPS work ". GPS works by use of radio signals from the satellites and timing, not by use of the magnetic field.
  • DanielMoragne
    Bob Sizemore said:
    The article states, "The magnetic field is why compasses and GPS work ". GPS works by use of radio signals from the satellites and timing, not by use of the magnetic field.
    I saw that too, and wondered about what the author was trying to say. Compasses, yes - GPS doubtful, unless the varying field effects the orbit of the satellites, or their signal timing.
  • rickv
    Yes, GPS works on precise timing coordinated among various satellites that emit timing signals. The satellites are equipped with atomic clocks so that they are all synchronized to the true, accurate time. Then any timing differences from multiple satellites received by the GPS device allows the device to know the precise relative distance it is from the satellites and 'triangulate' its position.

    Compasses are often integrated into the GPS device as an aid for orienting a displayed map, routing and other features provided on the GPS device itself. However, the GPS positioning information is not dependent on the earth's magnetic field.
  • GTJohn70
    admin said:
    European satellites are investigating the development of two distinct weak points within the South Atlantic Anomaly of Earth's magnetic field.

    'Vigorous' magnetic field oddity spotted over South Atlantic : Read more
    This article just demonstrates how foolish all the climate change rhetoric is. Earth is not permanent, humans on earth are not permanent. There are so many things that can happen that we have no control over - any of which will end humanity. The magnetic field is just one of those things. Dr. Fauci funding gain-of-function for viruses is another. There are countless others and one day, one of them will probably happen. So enjoy life today, stop worrying about stupid stuff and do something meaningful with your life.
  • TimLong
    What is the relation to the rapid motion of the northern magnetic pole?
  • Sally
    Have a play with this https://maps.ngdc.noaa.gov/viewers/historical_declination/
  • spkay31
    "The magnetic field is why compasses and GPS work ", sadly I have come to the conclusion that Livescience is largely written by authors who could not actually get a job actually using science.

    The anomalies in the earth's magnetic field are not only well known but also somewhat expected. The earth's internal liquid iron core is essentially 2 major rivers of molten material flowing in opposite directions. At somewhat regular intervals over the earth's history those slow drastically and become disorganized for a short period of time before reforming and beginning to flow in the opposite directions, i.e. one that had a basically clockwise flow will now resume counter-clockwise and vice versa. The pattern we are now in has not reversed on a long time (approx 780,000 years) and the previous reversals were on a much shorter time scale ( 200-400K years). Changes in the magnetic field have a real effect on the earths environment though the changes do happen slowly but the possibility for more rapid changes is always a possibility given the very random nature of the change at the point of field reversal.
  • TempForumHandleRename5874
    Totally off topic, bit I want to thank you guys for these articles and discussions. I usually read articles like this in the news, but here i don’t have to filter through anything else. Everything I’m interested in is lumped together discussing current events in science. I’m no expert, so I usually don’t comment, but i love being enriched in every which way your audience and your article deliverers the discussion and when there is so much sadness to read in the news I just wanted to thank you all for giving us alternative topics. Ok emotional dorky delivery :D
  • Hayseed
    It would be much more interesting if the earth flipped 180, instead of the field.

    Interesting seasons and tides while flipping.
  • Sally
    Hayseed said:
    It would be much more interesting if the earth flipped 180, instead of the field.

    Interesting seasons and tides while flipping.
    Catastrophic even... read any Velikovsky?