Using 11 years of magnetic field measurements from the European Space Agency’s Swarm satellite constellation, scientists have discovered that the weak region in Earth’s magnetic field over the South Atlantic—known as the South Atlantic Anomaly—has expanded by an area nearly half the size of continental Europe since 2014.

Earth’s magnetic field is vital to life on our planet. It is a complex and dynamic force that protects us from cosmic radiation and charged particles from the sun.

It is largely generated by a global ocean of molten, swirling liquid iron that makes up the outer core around 3,000 km beneath our feet. Acting like a spinning conductor in a bicycle dynamo, it creates electrical currents, which in turn, generate our continuously changing electromagnetic field —but in reality the processes that generate the field are far more complex.