APR 24, 2024 11:15 AM PDT

Unveiling Earth's Ancient Shield: A 3.7-Billion-Year-Old Magnetic Record

How long has the Earth’s magnetic field existed? This is what a recent study published in the Journal of Geophysical Research Solid Earth hopes to address as a team of international researchers discovered evidence indicating that the Earth’s magnetic field existed as far back as 3.7 billion years ago and was approximately half as strong as it is today, which puts this as the oldest evidence of Earth's magnetic field to date. This study holds the potential to help scientists better understand the processes responsible for producing the Earth's magnetic field, which is responsible for shielding the planet’s atmosphere and surface from harmful space weather.

For the study, the researchers analyzed iron-bearing rock formations among the Isua Supracrustal Belt in Southern West Greenland whose iron particles record the direction and strength of the magnetic field and are locked in time due to crystallization. In the end, the researchers determined that the iron particles exhibit evidence of the Earth’s magnetic field from 3.7 billion years ago along with its strength being half of what it is today.

Image of the iron rock formation discovered in the Isua Supracrustal Belt in Southern West Greenland exhibiting evidence of the Earth’s magnetic field from 3.7 billion years ago. (Credit: Claire Nichols)

“Extracting reliable records from rocks this old is extremely challenging, and it was really exciting to see primary magnetic signals begin to emerge when we analyzed these samples in the lab. This is a really important step forward as we try and determine the role of the ancient magnetic field when life on Earth was first emerging,” said Dr. Claire Nichols, who is an Associate Professor of the Geology of Planetary Processes at the University of Oxford and lead author of the study.

As noted, the Earth’s magnetic field is essential for protecting the Earth’s surface from harmful space weather, which could strip our atmosphere and enable radiation to reach the surface. While the magnetic field is generated within the Earth’s outer core of churning liquid metal, records of the magnetic field are often found in rocks, as depicted in this study.  

What new discoveries will researchers make about the Earth’s ancient magnetic field in the coming years and decades? Only time will tell, and this is why we science!

As always, keep doing science & keep looking up!

Sources: Journal of Geophysical Research Solid Earth, NASA, EurekAlert!

About the Author
Master's (MA/MS/Other)
Laurence Tognetti is a six-year USAF Veteran who earned both a BSc and MSc from the School of Earth and Space Exploration at Arizona State University. Laurence is extremely passionate about outer space and science communication, and is the author of "Outer Solar System Moons: Your Personal 3D Journey".
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