shield, protecting us from harmful cosmic radiation.
Without it, Earth would be bombarded by charged particles from space, much like Mars, which lacks a strong magnetic field and struggles to support life.
Scientists have long believed that Earth’s magnetic field is created by the movement of liquid iron and nickel in the outer core, a process known as the “dynamo effect.”
As Earth slowly cools, heat causes convection currents—swirling flows of molten metal—in the outer core. These flows, twisted by Earth’s rotation, generate electric currents that in turn create magnetic fields.
But there has been one big mystery: Earth’s inner core, a solid ball of iron, only began to form about a billion years ago. Before that, the core was entirely liquid.
So how could Earth have had a magnetic field when there was no solid core to help drive those convection currents?
Now, a team of researchers from ETH Zurich in Switzerland and Southern University of Science and Technology (SUSTech) in China may have found the answer.
Their new study, published in Nature, uses advanced computer simulations to show that even with a fully liquid core, Earth could have generated a stable magnetic field similar to the one we have today.
The scientists used one of the world’s most powerful supercomputers—Piz Daint in Lugano, Switzerland—to run their simulations. They created a virtual model of early Earth and tested whether the liquid core alone could drive the dynamo effect.
Their breakthrough was minimizing the impact of core viscosity (how thick or sticky the molten material is) in the model, something no previous study had achieved. Under these more realistic conditions, the model showed that a magnetic field could indeed have existed billions of years ago.
This discovery sheds new light on how early life on Earth may have survived. It suggests that the magnetic shield was already in place, blocking deadly solar radiation and allowing life to emerge and evolve safely on the planet’s surface.
Beyond Earth, these findings also help scientists understand the magnetic fields of other planets and stars, including gas giants like Jupiter and Saturn, or even the sun itself.
The Earth’s magnetic field is more than just a relic of the past—it remains essential today.
It protects satellites, supports navigation systems, and shields our technology from solar storms. As the magnetic field shifts and evolves, understanding its origin and behavior becomes increasingly important for the future of our planet and civilization.
Source: ETH Zurich.
