A new study has suggested that Earth's magnetic shield is much older than it was previously thought, and is at least four billion years old.
John Tarduno, a geophysicist at the University of Rochester, said that a strong magnetic field provided a shield for the atmosphere and this was important for the preservation of habitable conditions on Earth.
The field protects Earth's atmosphere from streams of charged particles shooting from the Sun. It helps prevent the solar winds from stripping away the atmosphere and water, which make life on the planet possible.
Tarduno's new results are based on the record of magnetic field strength fixed within magnetite found within zircon crystals collected from the Jack Hills of Western Australia. The zircons were formed over more than a billion years and have come to rest in an ancient sedimentary deposit. By sampling zircons of different age, the history of the magnetic field can be determined.
Tarduno found that the minerals revealed varying magnetic directions, convincing him that the intensity measurements recorded in the samples were indeed as old as 4.4 billion years.
The study is published in the journal Science.
