by A weak spot in Earth’s magnetic field is growing over the South Atlantic Ocean, according to more than a decade of satellite data collected by scientists.
The magnetic field surrounding the Earth protects the planet from cosmic rays and particles charged by the sun. Scientists think it is generated by the Earth’s outer core, according to a press release from the European Space Agency. The ESA said the “global ocean of molten, swirling liquid iron” in that layer of the planet creates electric currents that generate the magnetic field.
The weak spot, known as the South Atlantic Anomaly, was first identified in the 19th century, the ESA said. It is located southeast of South America and southwest of Africa. In this region, the planet’s magnetic field drops, NASA said. Satellites that pass over them are hit by higher doses of incoming radiation, which can cause technical problems and even power outages.
The South Atlantic Anomaly in 2014. / Credit: ESA (data source: Finlay, CC et al., 2025)
The ESA studied the site for 11 years, from 2014 to 2025. Three different satellites, known as Swarm, accurately measured the planet’s magnetic signals during that time. The data has been published in the journal Science Direct.
The satellite data showed that the South Atlantic Anomaly had expanded to cover an area “almost half the size of continental Europe”, or about two million square kilometers. The rate of weakening of the area has increased since 2020, the ESA said, with different parts of the anomaly changing at different rates.
“The South Atlantic Anomaly is not just a single block,” said lead author Chris Finlay, professor of geomagnetism at the Technical University of Denmark, in the ESA press release. “It changes differently towards Africa than it does near South America. Something special is happening in this region that is weakening the field in a more intense way.”
The South Atlantic Anomaly in 2025. / Credit: ESA (data source: Finlay, CC et al., 2025)
Finlay said that magnetic field lines that emit from the core bounce back into it. It’s not clear why this happens, but it contributes to the weakening of the anomaly in those areas, the ESA said.
The ESA satellites detected even more changes in the Earth’s magnetic field. In the Southern Hemisphere there is another area where the magnetic field is particularly strong. Two other anomalies exist in the Northern Hemisphere: one near Canada and one over Siberia. Both are stronger than the rest of the field. However, the area near Canada has shrunk by an area the size of India, while the area above Siberia has grown by an area the size of Greenland, the ESA said.
A view of ESA’s Swarm satellites. / Credit: ESA/AOES Medialab
The satellites will continue to study the planet’s magnetic field in the coming years, the ESA said.
“It’s truly amazing to see the big picture of our dynamic Earth thanks to Swarm’s extensive time series,” Swarm Mission manager Anja Stromme said in a statement. “The satellites are all healthy and providing excellent data, so we can hopefully extend that record beyond 2030, when solar minimum will enable more unprecedented insights into our planet.”
Netanyahu says Hamas must disarm itself or all hell will break loose
Instagram introduces new restrictions for teenage users
Trump accuses China of “intentionally not buying American soybeans” and threatens trade reprisals
