Swarm reveals growing weak spot in Earth's magnetic field

Summary

Credit: European Space Agency 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 3000 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. Swarm, an Earth Explorer mission developed under ESA's Earth Observation FutureEO program, comprises a constellation of three identical satellites that precisely measure the magnetic signals that stem from Earth's core, mantle, crust and oceans, as well as from the ionosphere and magnetosphere. Thanks to this exceptional mission, scientists are gaining more insight into the different sources of magnetism to help understand how and why the magnetic field is weakening in some places and strengthening in others. The weak field South Atlantic Anomaly was first identified southeast of South America back in the 19th century. Today, the South Atlantic Anomaly is of particular interest for space safety, as satellites passing over the region are faced with higher doses of incoming radiation. This can lead to malfunctions or damage to critical hardware, and even blackouts. Published in Physics of the Earth and Planetary Interiors, the latest results from the Swarm mission reveal that while the South Atlantic Anomaly expanded steadily between 2014 and 2025, a region of the Atlantic Ocean southwest of Africa ...