Earth already had a strong magnetic field 3.2 billion years ago

Posted on Sunday, Apr 08 2007 @ 03:30 CEST by Thomas De Maesschalck
Geophysicists at the University of Rochester came to the conclusion that our planet already had a strong magnetic field 3.2 billion years ago. This contradicts earlier beliefs:
“The intensity of the ancient magnetic field was very similar to today’s intensity,” says John Tarduno, professor of geophysics in the Department of Earth and Environmental Sciences at the University of Rochester. “These values suggest the field was surprisingly strong and robust. It’s interesting because it could mean the Earth already had a solid iron inner core 3.2 billion years ago, which is at the very limit of what theoretical models of the Earth’s formation could predict.”

Geophysicists point to Mars as an example of a planet that likely lost its magnetosphere early in its history, letting the bombardment of radiation from the sun slowly erode its early atmosphere. Theories of Earth’s field say it’s generated by the convection of our liquid iron core, but scientists have always been curious to know when Earth’s solid inner core formed because this process provides an important energy source to power the magnetic field. Scientists are also interested in when Earth’s protective magnetic cocoon formed. But uncovering the intensity of a field 3.2 billion years in the past has proven daunting, and until Tarduno’s research, the only data scientists could tease from the rocks suggested the field was perhaps only a tenth as strong as today’s.

Tarduno had previously shown that as far back as 2.5 billion years ago, the field was just as intense as it is today, but pushing back another 700 million years in time meant he had to find a way to overcome some special challenges. Tarduno, however, isolates choice, individual crystals from a rock, heats them with a laser, and measures their magnetic intensity with a super-sensitive detector called a SQUID—a Superconducting Quantum Interface Device normally used in computing chip design because it’s extremely sensitive to the tiniest magnetic fields.


About the Author

Thomas De Maesschalck

Thomas has been messing with computer since early childhood and firmly believes the Internet is the best thing since sliced bread. Enjoys playing with new tech, is fascinated by science, and passionate about financial markets. When not behind a computer, he can be found with running shoes on or lifting heavy weights in the weight room.



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