South Atlantic Anomaly Expands, Shifts Toward Africa

Scientists report that a long-known weak spot in Earths magnetic field over the South Atlantic and South America has expanded markedly and is shifting westward toward Africa, according to a study released this month that analyzed 11 years of satellite data. The region, known as the South Atlantic Anomaly, has grown by an area roughly comparable to half the size of continental Europe since 2014 and is linked to changes deep within the planet that can increase radiation exposure for spacecraft passing overhead.

Researchers reached the conclusions by examining continuous measurements from the European Space Agencys Swarm satellite constellation, which has been mapping magnetic signals from Earths core, mantle, crust and atmosphere since 2013. The study, published in the journal Physics of the Earth and Planetary Interiors, attributes the anomaly's growth and motion to turbulent flows of molten iron in the liquid outer core and to localized features called reverse flux patches, where magnetic field lines behave opposite to the usual pattern.

"The South Atlantic Anomaly is not just a single block," said lead author Chris Finlay, a professor of geomagnetism. "Its changing differently...