Since 2013, the ESA’s Swarm mission – comprising three satellites orbiting our planet at an altitude of between 450 and 530km – has been learning more about Earth’s magnetic field.

This mysterious force – which is formed thanks to the way molten iron moves around the outer core of our planet, generating a current as it goes – is fundamental to life as we know it, as it protects our planet from the Sun’s radiation.

There is still so much we have left to understand about our planet’s magnetic field though, with Swarm measuring exactly how this magnetic field works, and why its forces are changing over time.

And a new study, recently published in the journal Physics of the Earth and Planetary Interiors offers more understanding than ever before, not just about how the magnetic field works but where – and why – it seems in places to be failing.

Across some parts of our planet, the magnetic field seems only to be getting stronger, while other locations are suffering from a weakening of the forcefield that once protected it.

But we’ve known this for a while, with something known as the South Atlantic Anomaly – a particularly weak area of the Earth’s magnetic field, where satellites are subject to higher cosmic radiation – identified back in the 19th century.

Things seem to be changing, however; nowadays the South Atlantic Anomaly, which is only getting larger, is being surpassed by a more rapidly weakening patch above the Atlantic Ocean to the southwest of Africa.

And it’s all to do with reverse flux patches, areas of unusual behavior between the molten iron in the outer core and the Earth’s rocky mantle, as the Technical University of Denmark’s Professor Chris Finlay explained in a statement:

“Normally we’d expect to see magnetic field lines coming out of the core in the southern hemisphere. But beneath the South Atlantic Anomaly we see unexpected areas where the magnetic field, instead of coming out of the core, goes back into the core. Thanks to the Swarm data we can see one of these areas moving westward over Africa, which contributes to the weakening of the South Atlantic Anomaly in this region.”

On the other hand, however, Swarm data proves that in places the Earth’s magnetic field is only getting stronger.

This is the case for a patch above Siberia, where – just like in the weakening areas – the ever-moving molten iron is leading to stronger electro-magnetic outputs, with a stronger electro-magnetic field as a result.

Among other things, this has also caused the Earth’s magnetic North Pole to steadily travel towards Siberia.

There is undoubtedly still a lot more to learn about this powerful field that protects our planet and its ecosystems from the incredible power of the Sun – and thanks to the ESA’s swarm mission, we are learning more and more about it all the time.

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