zpostcode
Earth's magnetic field formed before the planet's core, study suggests
Apr 26, 2025 12:06 AM

Earth's magnetic field may have been similarly as strong 3.7 billion years ago as it is today, pushing the earliest date for this planetary protective bubble back 200 million years.

The timing puts the magnetic field in play around the same time life was first emerging on Earth. The oldest fossils on the planet bacterial mats called stromatolites date back 3.5 billion years, with some researchers claiming to have found stromatolites as old as 3.7 billion years.

The new study suggests that at that time, the planet had a protective magnetic bubble around it that deflected cosmic radiation and damaging charged particles from the sun.

However, the flow of solar charged particles was much stronger at that time, said Claire Nichols, an Earth scientist at the University of Oxford and lead author of the study, which was published April 24 in the Journal of Geophysical Research. That strong "solar wind" would have stripped away the magnetosphere protecting the planet, meaning Earth was far less shielded than it is today. That finding has implications for the search for alien life.

"When we're looking for life on other planets, having a magnetic field is not necessarily key," Nichols told Live Science. "Because actually, with a much smaller magnetosphere, it still looks like life was able to develop."

The hunt for extraterrestrial life is only one reason to wonder about Earth's magnetic field. Not every planet has a magnetosphere, and researchers aren't quite sure what kicked Earth's into gear. Today, the magnetic field is driven by the churning of the liquid part of the core and the transfer of heat from the solid inner core to the convective outer core as the former cools. But researchers think the core didn't solidify until about a billion years ago.

Co-author Athena Eyster standing in front of a large exposure of banded iron formation, the iron rich deposit from which ancient magnetic field signals were extracted.

Nichols and her team went far out of the way to seek out signs of the ancient magnetic field 93 miles (150 kilometers) inland of Nuuk, Greenland, to a spot on the edge of the ice sheet accessible only by helicopter.

The rocks from this region, called the Isua Supracrustal Belt, are some of the oldest surviving portions of Earth's crust on the planet. They contain iron-rich formations that preserve information about the magnetic field's direction and strength when the rocks formed.

Researchers can also look at folds in the rock caused by later geological upheaval to see if the direction of the magnetic field matches the orientation of the rock. If it doesn't, the magnetic field predates those geological events, for which researchers often know the ages.

RELATED STORIESWhy does Earth have magnetic poles?

Strange radio signals detected from Earth-like planet could be a magnetic field necessary for life

Weird dent in Earth's magnetic field is messing with auroras in the Southern Hemisphere

Using these methods, the researchers found that 3.7 billion years ago, the magnetic field was at least 15 microtesla in strength. That's half the average strength of the magnetic field today. But it's a lower-end estimate, Nichols said, so it's possible that the field back then was around as strong as it is now.

"Whatever is driving the magnetic field in the core was just as powerful before the core was solidified," Nichols said.

The researchers are now interested in delving more deeply into the connections between the ancient magnetic field and Earth's atmosphere. Around 2.5 billion years ago, the atmosphere suddenly experienced a flood of oxygenation. This was partially due to the development of photosynthesis, Nichols said, but the strength of the magnetic field can affect which gases stay within the atmosphere and which ones escape into space.

"I'm really interested to know if the magnetic field has played a role in the evolution of Earth's atmosphere over time," Nichols said.

Comments
Welcome to zpostcode comments! Please keep conversations courteous and on-topic. To fosterproductive and respectful conversations, you may see comments from our Community Managers.
Sign up to post
Sort by
Show More Comments
Recommend >
Anna Meares
  Anna Meares Australian cyclist Actions Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Anna-Meares Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Anna-Meares Also known as: Anna Maree Devenish Meares Written by Joan Hibler Joan Hibler is a senior editor at Encyclopædia Britannica. Joan Hibler Fact-checked by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas...
Google Gemini
  Google Gemini generative AI Actions Share Share Share to social media Facebook X URL https://www.britannica.com/technology/Google-Gemini Share Share Share to social media Facebook X URL https://www.britannica.com/technology/Google-Gemini Also known as: Google Bard Written by Frannie Comstock Frannie Comstock is a writer based in Chicago. Frannie Comstock Fact-checked by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they...
Consumer discretionary sector: Investing in companies that make life a bit sweeter
     You have material needs in life—and also desires and wants. Companies in the consumer discretionary sector of the stock market make products that you may intensely covet but not need. For that reason, companies that offer goods and services subject to discretionary spending can (and do) see dramatic changes in demand, unlike the consumer staples sector.   Investing in the...
Industrials sector: Investing in big companies that do big things
     When envisioning the pillars of American industry, numerous products and services come to mind: heavy machinery for transportation, farming, and defense; building products, electrical equipment, and machine parts; and an array of functions, from supply chain consulting to basic facility services, like plumbing and janitorial duties.   What is the industrials sector?The industrials sector comprises companies that produce capital goods—products...
Information Recommendation
Naval Battle of Campeche
  Naval Battle of Campeche Mexican history [1843] Actions Cite verifiedCite While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions. Select Citation Style MLA APA Chicago Manual of Style Copy Citation Share Share Share to social media Facebook X...
Consumer staples sector: Investing in stocks that provide the basics for living
     Some things you just can’t live without. Consumer staples are products that are essential or that you’re likely to purchase regardless of your personal finances or how the economy is performing. Food, drinks (including alcoholic beverages), tobacco, and household and personal care items are all considered consumer staples.   The sector comprises a broad swath of companies that make, market,...
...
spot price
  also called:cash priceSpot price is the current price at which you can buy or sell an asset for immediate delivery and settlement. Also called the cash price, spot prices typically fluctuate throughout the day due to changing supply, demand, and expectations. The spot price of physical goods will also vary by region due to local supply and demand as well...
Anne Lamott
  Anne Lamott American author Actions Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Anne-Lamott Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Anne-Lamott Written by Laura Payne Laura Payne is a freelance writer whose work covers many topics. She is a former Wayne State University linguistics instructor. Laura Payne Fact-checked by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's...
The Tête à Tête
  The Tête à Tête painting by William Hogarth Actions Share Share Share to social media Facebook X URL https://www.britannica.com/topic/The-Tete-a-Tete Share Share Share to social media Facebook X URL https://www.britannica.com/topic/The-Tete-a-Tete Also known as: “Marriage A-la-Mode: 2, The Tête à Tête”, “Shortly After the Marriage” Written by Ana Finel Honigman Ana Finel Honigman is a New York- and London-based critic, curator, and...
Leslie Jones
  Leslie Jones American actress Actions Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Leslie-Jones Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Leslie-Jones Also known as: Annette Leslie Jones Written by Leigh Goldstein Leigh Goldstein is a feminist media researcher based in Montreal. Leigh Goldstein Fact-checked by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas...
Ted Koppel
  Ted Koppel American journalist and news broadcaster Actions Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Ted-Koppel Share Share Share to social media Facebook X URL https://www.britannica.com/biography/Ted-Koppel Also known as: Edward James Martin Koppel Written and fact-checked by The Editors of Encyclopaedia Britannica Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of...