Scientists are intrigued by ‘breach’ in Earth’s magnetic field

Scientists are watching closely for a growing “breach” in Earth’s magnetic field across a strip of the Atlantic Ocean stretching from South Africa in the west to Brazil.

In this area, known as the South Atlantic Anomaly, the magnetic field – the invisible shield that protects the planet from radiation and charged particles from the sun – is weaker than normal. While not considered dangerous to humans, experts say the weak spot could cause problems or permanent damage to satellites surrounding Earth that are exposed to energetic particles as they fly in the region.

“These particles can wreak havoc on satellite instrumentation, so it is good to follow the South Atlantic anomaly, and in particular its changing shape, so that we can take preventative action,” Terence Sabaka, geophysicist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, told me.

Scientists have known about the weak point of Earth’s magnetic field for decades, but new research suggests that the South Atlantic anomaly is growing, spreading further west towards the Pacific Ocean, and weakening further.

“Satellite measurements, along with theoretical modeling, predict that the area will be larger in the next five or more years, and that the strength of the magnetic field in that area will be even weaker,” Weijia Kuang, geophysicist and mathematician at NASA’s Goddard Geodesy and Geophysics Laboratory, said.

Kuang added that the weak spot also appears to be splitting in half, although it is not yet known what specifically drives this process.

Earth’s magnetic field is generated by the constant movement of liquid metal in the planet’s iron-rich outer core, about 1,800 miles below the surface. As these molten deposits move, they produce electrical currents that fuel the Earth’s magnetic field and effectively turn the planet into a giant magnet.

But the constant churning in the outer core means that the magnetic field is tilted, which is why the magnetic poles are not perfectly aligned with the north and south geographic poles of the Earth. These dynamics deep within the planet also create fluctuations and instability in the magnetic field.

In general, the magnetic field is strongest at the poles and weakest at the equator, but more research is needed to understand the precise cause of the South Atlantic anomaly.

“It’s like a weakness on top of a weakness,” Sabaka said, adding that while there are other places where the magnetic field is less intense, the one over the Atlantic is by far the best. biggest and most meaningful.

Sabaka and Kuang have mapped the South Atlantic anomaly, but more data will help them refine their models and make more accurate predictions of how the weak point might change over time.

Kuang said the information will not only help protect satellites and other spacecraft orbiting Earth, but could also give scientists a better understanding of the processes that have taken place deep in the planet for hundreds of thousands. or millions of years.

“It gives us a very, very important window to probe the inner properties of the Earth,” he said, “and to understand the Earth as a whole as it evolves.”