Something extraordinary is happening above the South Atlantic Ocean. A giant magnetic anomaly, comparable to a “hole” in the Earth’s magnetic field, is growing and evolving under the watchful eyes of NASA researchers. The phenomenon, which may date back millions of years, is revealing new mysteries about how our planet works.
A threat to satellites
The magnetic anomaly, called South Atlantic Anomaly (SAA), is a serious concern for NASA. The agency's satellites and spacecraft are particularly vulnerable to the weakening of the magnetic field within this region, exposing them to charged particles from the Sun. During the passage through this area, technological systems may malfunction or short circuit.
Control centers take action
Solar particle beams can produce low-level glitches, but they also carry the risk of causing significant data loss or permanent damage to key components.
For this reason, satellite operators are forced to regularly shut down onboard systems before spacecraft enter the magnetic anomaly zone.
A unique study opportunity
Terry Sabaka of the NASA's Goddard Space Flight Center explains that the magnetic field is actually an overlapping of fields from many sources. The main source is considered a swirling ocean of molten iron within Earth's outer core, thousands of kilometers below the surface. The movement of this mass generates electric currents that create the Earth's magnetic field, but not in a uniform way.
The causes of the phenomenon
A huge deposit of dense rock called African Large Low Shear Velocity Province, located about 2.900 kilometers beneath the African continent, appears to disturb the generation of the field, causing the weakening effect. This effect is amplified by the tilt of the planet's magnetic axis.
According to the geophysicist and mathematician Weijia Kuang, the observed magnetic anomaly can be interpreted as a consequence of the weakening of the dipolar field dominance in the region. A localized field with reversed polarity grows strongly in the SAA region, making the field intensity very weak.
Magnetic Anomaly, Surprising New Discoveries
The latest research has revealed surprising aspects of the phenomenon. A study led by heliophysics Ashley Greeley in 2016 showed that the magnetic anomaly moves slowly, as confirmed later from CubeSats monitoring in 2021. Even more remarkable is the discovery that the phenomenon it seems to split in two, with researchers who in 2020 they identified two distinct cells.
Contrary to what one might think, the magnetic anomaly is not a recent phenomenon. A study published in July 2020 suggests that it may have been influencing Earth as early as 11 million years ago. This could indicate that This is not a precursor to a reversal of the Earth's magnetic field, an event that actually happens, but on time scales of hundreds of thousands of years.
The importance of continuous monitoring
NASA continues to closely monitor the evolution of the magnetic anomaly. As it points out Saba:
Even though SAA is moving slowly, it is going through some changes in morphology, so it is important to continue observing it through continuous missions. Because this is what helps us create models and forecasts.
As scientists continue to study this intriguing phenomenon, one thing is certain: the South Atlantic Magnetic Anomaly is providing us with a unique opportunity to better understand our planet’s complex magnetic system. Future observations and research could not only help us better protect our satellites, but also reveal new secrets about Earth’s internal dynamics.
