We know that our planet has two poles, and the magnetic field between the poles protect us from cosmic rays and solar winds. However, a recent study has revealed that there was a period in the planet’s history when it had multiple poles, and the earth’s magnetic field was very erratic. These findings have been published in Geographical Research Letters.
Earth’s magnetic field is caused by an effect known as geodynamo created by the rotation of Earth’s liquid iron core around a smaller solid core. This motion is driven by the loss of heat from the core and the solidification of the inner core.
However, the solid core did not exist always. The bi-polarity of the planet remained unchanged for most of its 4.5 billion year history. However in the Neoproterozoic Era, between .5 to 1 billion years ago, evidence suggests that the Earth sometimes had more than two poles. The proof of this phenomenon could be seen in the very old rocks, which retain the signs of magnetic polarity of their times.
The polarity of Earth remained until one billion years when the planet’s core started to solidify, and the magnetic polarity went haywire. Some poles started appearing, and this phenomenon continued till the solid core settled in.
The latest findings are in line with the bizarre fluctuations in magnetic field direction seen in the geologic record around 600 to 700 million years ago. The implications of such magnetic variations are dramatic. The planet’s magnetic field acts as armor against harsh radiations coming towards the globe from deep space or by sun spot activities on Sun. Without the protective magnetic field, the planet will lose much of its atmosphere and become a barren heavenly body just like our Moon.
