Earth’s magnetic shield much older than previously thought

And finally, study co-author Rory Cottrell says, “Some have postulated that the Earth’s magnetic field is leaking out the wrong way at that particular spot”.

Researchers on Thursday stated proof entombed in tiny crystals retrieved from the outback of western Australia signifies the magnetic subject arose at the very least four.

In comparison, the values measured by the authors in the ancient zircons were far higher, indicating the presence of a geodynamo some 4.22 billion years ago.

This puts its formation before an event called the Late Heavy Bombardment, which involved all the planets in the Solar System getting pummelled by comets and asteroids for two or three hundred million years.

The intensity of the magnetic fields that the samples recorded suggests the presence of an ancient geodynamo, the researchers said.

The measurements taken by Tarduno’s team reveal that the magnetic field likely helped protect the planet at a time when solar winds were 100 times stronger than they are today.

The study was led by John Tarduno, geophysicist from the University of Rochester, and carried out by researchers from South Africa’s University of the Witwatersrand and University of KwaZulu-Natal.

The researcher found that a 30% fall in magnetic field intensity was there from 1225 to 1550 A. D.

Use these social-bookmarking links to share Earth’s magnetic field much older than previously thought. The findings suggest these fascinating reversals, which can take up to 15,000 years to complete, have generally originated in the core region beneath southern Africa.

The zircons, which are billions of years old, contain a naturally occurring magnetic iron oxide (magnetite), which records the strength of the magnetic field at the time it solidified from its molten state.

The oldest available minerals can tell scientists the direction and the intensity of the field at the earliest periods of Earth’s history.

To Tarduno’s group, that consistently recurring spot of weakening suggests that a permanent feature deep below the Earth’s surface may be generating the South Atlantic Anomaly and might therefore play a role in the reversal of the Earth’s magnetic field. “Those models need to be rethought to include potential ways of cooling Earth’s interior early on”.

“These new results represent the first time that we know anything about the Earth’s magnetic field prior to the great heavy bombardment 3.9 billion years ago when the planets experienced a huge meteor storm”, says Nimmo. “But then, sometime after 4 billion years ago, it died off. If you compare the evolution of Earth and Mars, Mars had a more dense atmosphere, and water, but it probably lost both to erosion from the solar wind because it didn’t have a magnetic field to protect them, whereas Earth always appeared to have had a strong magnetic shield”. This could explain why Mars’ atmosphere is so thin, he added, as well as why the planet “was unable to sustain life”.

The scientists detailed their findings in the July 31 issue of the journal Science.