ESA Swarm Mission: The First-Ever Images of Earth's Mysterious Second Magnetic Field

Wednesday, 11 April 2018 - 11:32AM
Physics
Earth
Wednesday, 11 April 2018 - 11:32AM
ESA Swarm Mission: The First-Ever Images of Earth's Mysterious Second Magnetic Field
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Image credit: YouTube

Say what you will about the many, many, many scientific inaccuracies in the 2003 disaster movie The Core, but it did teach a generation about the Earth's iron core and how its motion creates the planet's magnetic field. In fact, Earth's magnetosphere is probably a lot more fascinating and weird than you imagine—take the South Atlantic Anomaly, or the fact that it's less powerful than a standard bar magnet.

 

Even more interesting? Earth has a second magnetic field, created wholly by the tides in the ocean. And now we know what it looks like.



When the Moon pulls on the oceans, it creates tides, which are massive patterns of ebb and flow spread across the planet. 

Because saltwater in electrically conductive, these movements start to generate a magnetic signal.

 

The signal is relatively weak (about 20,000 times less powerful than the Earth's magnetic field), but after years of trying to pin it down, the European Space Agency has completed a mission to map the oceans' magnetic field.

 

This project has been named "Swarm" by the ESA, and is actually incredibly useful for studying our planet, especially the deep parts of the oceans:





According to Nils Olsen, of the Technical University of Denmark, "Since oceans absorb heat from the air, tracking how this heat is being distributed and stored, particularly at depth, is important for understanding our changing climate."

 

The magnetic data from Swarm also allows scientists to gain insight into the upper mantle and lithosphere, which can help us to learn more about the activity of earthquakes and volcanoes. In fact, Swarm is already changing what we know about the Earth's core—according to Chris Finlay:



"Swarm data are now enabling us to map detailed changes in Earth's magnetic field, not just at Earth's surface but also down at the edge of its source region in the core. Unexpectedly, we are finding rapid localised field changes that seem to be a result of accelerations of liquid metal flowing within the core."

It may not grab the same headlines as smashing together particles to create antimatter, but the Earth's magnetic fields may prove to be just as fascinating.

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