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The geomagnetic field is a fundamental property of our planet – it protects us from the solar wind, helps us navigate, and observations of local and global geomagnetic field variation on timescales from hours to years reveals information on a multitude of Earth and near-Earth phenomena such as ocean circulation pattern, tides, plasma bubbles in the Earth ionosphere and jet-streams in the core of our planet. Magnetic field fluctuations associated with natural phenomena such as earthquakes and hurricanes can also be observed, and close monitoring of the geomagnetic field variations by satellite systems will further enhance our knowledge and understanding of the coupling of our complex Earth and near-Earth system.


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Unravelling Earth's magnetic field

21 March 2017

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ESA's Swarm satellites are seeing fine details in one of the most difficult layers of Earth's magnetic field to unpick - as well as our planet's magnetic history imprinted on Earth's crust.

Earth's magnetic field can be thought of as a huge cocoon, protecting us from cosmic radiation and charged particles that bombard our planet in solar wind. Without it, life as we know it would not exist.

Most of the field is generated at depths greater than 3000 km by the movement of molten iron in the outer core. The remaining 6% is partly due to electrical currents in space surrounding Earth, and partly due to magnetised rocks in the upper lithosphere - the rigid outer part of Earth, consisting of the crust and upper mantle.

Although this 'lithospheric magnetic field' is very weak and therefore difficult to detect from space, the Swarm trio is able to map its magnetic signals. After three years of collecting data, the highest resolution map of this field from space to date has been released.

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