The European Space Agency has been working on mapping the Earth’s lithosphere – the rigid, outermost layer of the Earth – by measuring its magnetic characteristics using its Swarm mission, and has now released a map (including an interesting, unembeddable video):
Magnetic anomaly: Bangui
Image Source: ESAEarth’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.
“By combining Swarm measurements with historical data from the German CHAMP satellite, and using a new modelling technique, it was possible to extract the tiny magnetic signals of crustal magnetisation,” explained Nils Olsen from the Technical University of Denmark, one of the scientists behind the new map.
This background is intriguing:
When new crust is generated through volcanic activity, mainly along the ocean floor, iron-rich minerals in the solidifying magma are oriented towards magnetic north, thus capturing a ‘snapshot’ of the magnetic field in the state it was in when the rocks cooled.
Since magnetic poles flip back and forth over time, the solidified minerals form ‘stripes’ on the seafloor and provide a record of Earth’s magnetic history.
Must be interesting analyzing that sort of information.
