ESA just discovered a second magnetic field surrounding Earth

If your news sources were saturated this morning with Mark Zuckerberg testifying to Congress, you’re not alone. But the Zuck’s media predominance has led to some pretty significant stories going all but unnoticed, not least of all the news that the European Space Agency (ESA) has discovered a second magnetic field surrounding our humble planet.

ESA just discovered a second magnetic field surrounding Earth

The discovery was made by a trio of satellites studying Earth’s magnetic field, or should we say fields plural now? The mission, entitled ‘Swarm’, was launched in 2013, and has amassed four years’ worth of data, a feat which has contributed to the mapping of this latest discovery. The satellites orbit at 300-530km (186-330 miles) around Earth, charged with the not-so-negligible task of collecting data on the planet’s magnetic properties.

So how does this newbie differ from the magnetic field we’ve long recognised? Their fundamentals are pretty similar: they’re both the product of a dynamo effect elicited by charged particles that move freely within a fluid. In fact, it’s our main magnetic field that’s responsible for the steady movement of molten rock under the Earth’s surface. It also has a bearing on the formation of particles in the Earth’s crust, an undertaking charted by the ESA in the magnificent map below.

Nonetheless, it’s the discovery of our planet’s second magnetic field which has electrified the science world. “It’s a really tiny magnetic field,” explained Technical University of Denmark physicist Nils Olsen to the BBC. “It’s about 2 – 2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than Earth’s global magnetic field,” he went on. “We have used Swarm to measure the magnetic signals of tides from the ocean surface to the seabed, which gives us a truly global picture of how the ocean flows at all depths – and this is new.”


But what of practical applications? Magnetic field 2.0, as we’ve informally dubbed it, could be used to hone models of global warming, namely by monitoring patterns of heat energy as they shift globally. Water – particularly vast bodies of it – is able to soak up huge amounts of heat, and knowing where such volumes of warm water are going could help identify the reasons behind the acceleration of global warming.

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But that’s not all. “In addition, because this tidal magnetic signal also induces a weak magnetic response deep under the seabed, these results will be used to learn more about the electrical properties of Earth’s lithosphere and upper mantle,” added Olsen. This could allow us to chart the currents of moving magma beneath the Earth’s crust in far more detail than is currently the case.

There you have it. As much as your schadenfreude is electrified by Zuckerberg’s gawky apologies to Congress, news of a second magnetic field warrants some serious attention. Particularly given the context of climate change’s onwards onslaught; this mini-field might just proffer the insight we need to hinder it.

Images: ESA

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