How much old is earths magnetics field

 How much old is earths magnetics field 



oldest remnants / बचा हुआ टुकड़ा  of the earth’s early magnetic field 


Geologists at MIT and Oxford University have found ancient rocks in Greenland that bear the oldest remnants / बचा हुआ टुकड़ा  of the earth’s early magnetic field.



The researchers determined that the rocks are about 3.7 billion years old and retain signatures of a magnetic field with a strength of at least 15 microtesla. The ancient field is similar in magnitude to the earth’s magnetic field today.


What is A microtesla (µT)

is a unit of magnetic flux density that is 1,000,000 times smaller than the SI unit, the tesla. It is equal to 10 −6 teslas


 Previous studies have shown evidence for a magnetic field on the earth that is at least 3.5 billion years old. The new study is extending the magnetic field’s lifetime by another 200 million years.


“If the earth’s magnetic field was around a few hundred million years earlier, it could have played a critical role in making the planet habitable


Magnetic shield


life-sustaining atmosphere and  shield the planet by solar radiation

 in its evolution, the earth was able to foster life, in part due to an early magnetic field that was strong enough to retain a life-sustaining atmosphere and simultaneously shield the planet from damaging solar radiation.


magnetic shield ,  evidence dating its existence to about 3.5 billion years ago.


The objective of the researchers

was to find rocks that still held signatures of the earth’s magnetic field when the rocks first formed. 


sample was collected 

team sampled from rock formations in the Isua Supracrustal Belt in southwestern Greenland.



The team returned to MIT with whole rock samples of banded iron formations — a rock type that appears as stripes of iron-rich and silica-rich rock. 


Given their composition, the researchers suspect the rocks were originally formed in primordial oceans prior to the rise in atmospheric oxygen around 2.5 billion years ago.


They used uranium to lead ratio and found that some of the magnetised minerals were likely about 3.7 billion years old. 


earth rocks likely harbored an ancient, 3.7-billion-year-old magnetic field, with a magnitude of at least 15 microtesla. Today, the earth’s magnetic field measures around 30 microtesla.

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