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.