Earth has a Second Magnetic Field According to ESA's Swarm Mission

ESA’s Swarm mission just uncovered an elusive magnetic field reportedly surrounding Earth.

The findings from the European Space Agency‘s Swarm mission revealed that our planet has an additional magnetic field. The discovery was reportedly made by Swarm’s three satellites that were launched into orbit in 2013 to study Earth’s magnetic behavior.

The satellites reportedly orbit around Earth at 300 to 530 km and have amassed four years’ worth of data about our planet’s magnetic properties. The recently discovered magnetic field was said to be extremely difficult to track because of its “tiny” size.

“It’s a really tiny magnetic field. It’s about 2-2.5 nanotesla at satellite altitude, which is about 20,000 times weaker than the Earth’s global magnetic field,” Nils Olsen, the head of the geomagnetism at the Technical University of Denmark, said in an interview with BBC.

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Our planet’s magnetic field is said to be produced mainly by an “ocean of superheated, swirling liquid iron” found at the Earth’s outer core. However, a small portion of it comes from the magnetized rocks in the crust and the flow of the ocean.

Apparently, seawater has never been considered a good source of Earth’s magnetism. However, the Swarm mission confirmed that it does make a tiny contribution.

ESA reported that when the salty ocean water flows through our planet’s magnetic field, it generates electric current, which in turn creates a magnetic signal. While it was said that the magnetic field produced by the tides are tough to measure, Swarm was able to do it.

“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,” Olsen further explained.

“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. 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.”

Aside from uncovering this new magnetic field, the Swarm mission was also able to map the magnetic field created by Earth’s crust.