You may know that the Moon is behind our oceans’ tides, drawing water to and from coasts with its gravitational pull. You might not know that this movement generates a weak magnetic field. The huge bodies of electrically-conductive salt water create a magnetic signal as they ebb and flow.
Now, a constellation of satellites has mapped this elusive magnetic field in impressive detail. Dubbed “Swarm,” the European Space Agency mission results stunned scientists at the European Geosciences Union General Assembly 2018 in Vienna, Austria.
Elusive magnetic field
The field has been incredibly difficult to track because it is so small. “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, head of geomagnetism at the Technical University of Denmark, told BBC News.