Understanding Earth’s formation through its magnetic field

Properties in our planet’s magnetic field could unlock the secrets of Earth’s formation 4.5 billion years ago

Theories speculating the origin of the Earth and Moon are numerous, with most involving a giant impact. However, researchers from teams at the University of Leeds and the University of Chicago claim to be able to narrow down the theories of the Earth-Moon formation and inform future research into what really happened.

Having analysed the dynamics of fluids and electrically conducting fluids, the team of researchers have concluded that the Earth must have been magnetized either before the impact or as a result of it.

Understanding the Earth’s formation and magnetic field

Professor David Hughes, University of Leeds, said: “Our new idea is to point out that our theoretical understanding of the Earth’s magnetic field today can actually tell us something about the very formation of the Earth-Moon system.

“At first glance, this seems somewhat surprising, and previous theories had not recognized this potentially important connection.”

Maintained by a geodynamo, a rotating and electrically conducting fluid in the outer core, the resilience of Earth’s magnetic field is the bases for this new research.

Professor Fausto Cattaneo, an astrophysicist at the University of Chicago, said: “A peculiar property of the Earth’s dynamo is that it can maintain a strong magnetic field but not amplify a weak one.”

“A peculiar property of the Earth’s dynamo is that it can maintain a strong magnetic field but not amplify a weak one.”

This means that if the Earth’s magnetic field were to get switched off or even reduced to a small level, it would not have the ability to kick-start again.

“It is this remarkable feature that allows us to make deductions about the history of the early Earth, including, possibly, how the Moon was formed,” added Professor Cattaneo.

Where did the Earth’s magnetic field come from?

Professor Hughes added: “And if that is true, then you have to think, where did the Earth’s magnetic field come from in the first place?

“Our hypothesis is that it got to this peculiar state way back at the beginning, either pre-impact or as an immediate result of the impact.”

“Either way, any realistic model of the formation of the Earth–Moon system must include magnetic field evolution.”