A research paper published in Geophysical Research Letters has unveiled that earth’s ancient magnetic field was quite different than the current field. At that time as per the researchers, the magnetic field used to originate from several poles rather than from now familiar two.
Earth’s magnetic field generates strong magnetic field that extends from the core out into the space. It protects the atmosphere from harmful radiations from the sun and the cosmos. If there would not have been magnetic field then as per the researchers the plant would have been exploded by cosmic radiation and there would have been no life on earth.
Earth’s outer core has liquid iron that generates a phenomenon known as geodynamo, which creates earth’s magnetic field. The motion is partly driven from the solidification of the inner core. But the researchers said that earth’s planetary core was not always solid.
In order to know what would have happened scientists have reconstructed the planet’s magnetic record by assessing the ancient rocks. From the assessment, the researchers came to know that the field has having two poles and being active and dipolar. The researchers have come to know that the magnetic fields had two poles from the very old rocks that still show signs of the magnetic polarity of those times.
The dipolarity of earth seems to have remained consistent through much of earth’s 4.5 billion year history. There could be a possibility that during the Neoproterozoic Era falling between .5 to 1 billion years ago, earth at certain times had more than two poles.
The researchers modeled the planet’s thermal history dating back to 4.5 billion years. From the model, it was found that the inner core should have started to solidify around 650 million years ago. In order to advance the research, the researchers used 3-D dynamo simulations. With this, the researchers looked at the expected changes in the magnetic field that might have taken place in that period.
Driscoll said, “What I found was a surprising amount of variability. These new models do not support the assumption of a stable dipole field at all times, contrary to what we’d previously believed”.
As per the research, earth around one billion years back would have from a modern-looking field to a weak magnetic field that had high fluctuation levels in terms of intensity and direction and originated from several poles and then, it moved back to a strong, two-pole magnetic field.
Around one billion years ago, earth was having a dipolar field. But when earth’s core started to solidify, the magnetic field became haywire and there were many poles instead of two. When the new solid core settled, the field returned to its regular number of poles.
The researchers mentioned that the findings could provide an explanation with regard to fluctuations seen in magnetic field directions around 600 to 700 million years ago. The findings are considered to have implications for earth’s thermal and magnetic history. The new model may provide important information about earth’s geologic history.