When the Earth's magnetic field switches, strange things happen. Now, the European Space Agency's Swarm satellite system has revealed exactly how our planets magnetism is changing.
Launched in 2013, Swarm is made up of three satellites which measure the strength of the Earth's magnetic field remotely. These new results are based on changes in the magnetic signals stemming from Earth's core; blue means the field is decreasing, magenta means it's increasing.
Measurements made over the past six months confirm the general trend that we expect to see: a gradual weakening of the planet's field. In fact, the most dramatic declines are over the Western Hemisphere, especially over Northern America.
But there are quirks. The magnetic field over the southern Indian Ocean has strengthened since January, for instance. And the results also show that magnetic North continues to move towards Siberia.
Over the coming months, researchers will further probe the data to understand how magnetic contributions from other sources—the mantle, crust, oceans, ionosphere and magnetosphere—affect our field, too. [ESA]