In the South Atlantic, there is an old acquaintance for space exploration: an anomaly where the Earth’s magnetic field is especially weak. The cause of this phenomenon is not known, but one thing is known: is growing.
The anomaly is deepening ever deeper, according to the annual report of the World Magnetic Model (WMM). Far from shrinking, has been expanding during 2023.
The problem is not new, since different agencies have closely monitored the anomaly for years. This is a kind of “dent” in the Earth’s magnetic field, Located in an area between South America and the South Atlantic, that reaches the coast of South Africa.
The anomaly is of particular interest to space agencies, as well as for satellite operators in low Earth orbit that circulate in the area.
The magnetic field not only protects people on the planet’s surface, but also satellites, ships and even space stations which are located in low orbits.
When they exceed this region, They remain vulnerable to radiation, solar winds and other phenomena which can cause problems in the operation of some onboard systems and in communication with the planet.
This is how the anomaly has advanced
In the case of this anomaly, the WMM report indicates that it has been deepening over time. According to the report, it has lost about 25 nanoteslas (a unit used to measure the magnetic field) at the surface level, and the area where the field intensity is located below 25,000 nanoteslas (nT) has increased by 7%.
For comparison, in 2020, the minimum intensity at surface level was 22,232 nanoteslaswhile in 2024 this number has fallen to 22,126 nT, that is, a drop of 106 nT in just four years.
This is also seen at 500 kilometers above sea level, where the International Space Station, Tiangong and Hubble are located. The figure has fallen from 18,428 nT to 18,349 nTthat is, just 79 nT.
The path of anomaly
Part of the report also addresses other details, such as that the center of the anomaly has moved approximately 20 kilometers westward during 2023, and that The average travel speed is 41 kilometers each year from the north magnetic pole and nine from the south magnetic pole.
The model is updated every five years and allows researchers’ predictions to be compared with observations of the Earth’s magnetic field, together with those made by the European Space Agency’s (ESA) Swarm satellites.
