Our planet’s magnetic field creates a
protective barrier against the sun’s harmful radiation. Without it life could not
exist. But how did our magnetic field begin?
Until recently scientists believed the field originated from the swirling
liquid iron of the outer core as it does today. But new evidence suggests that the
ancient magnetic field may actually have originated from a giant magma ocean deep
inside the mantle that existed between 4.5 and 2.5 billion years ago. Then, two billion years after the Earth
was formed, the liquid mantle started to solidify while the core began to release its
trapped heat. The movement of heat from the core triggered a convective fluid motion strong enough to generate a magnetic field. About half a billion years ago, the inner
core cooled enough to start solidifying. To this day the solid core continues to
grow, driving the forces that produced the
Earth’s magnetic field as we know it today.