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| ESA Swarm mission. / ESA |
The main reminders that we have from the planet that dynamic processes take place inside it are volcanic eruptions or earthquakes. But other, more elusive processes also occur under our feet, deep within the Earth.
Scientists on the European Space Agency's (ESA) Swarm satellite mission have discovered an entirely new type of magnetic wave "that sweeps across the outermost part of Earth's outer core every seven years," explained in a statement issued by the ESA.
A discovery presented during the 'Living Planet' symposium offers a great opportunity to discover a world that we will never be able to see.
What are the objectives of the mission?
As explained in the statement, the Earth's magnetic field is like a huge bubble that protects us from the attack of cosmic radiation and charged particles carried by powerful winds that escape the Sun's gravitational pull and flow through the Solar System.
Without this field, life would not exist. In this way, understanding how and where it was generated, or why it interacts with the solar wind, can have really important benefits for society. For example, solar storms can damage communication networks, navigation systems, and satellites, so while we can't do anything about changes in the magnetic field, understanding this invisible force helps us prepare.
In this sense, most of the magnetic field is generated by an ocean of superheated liquid iron that forms in the outer core of the Earth, 3,000 kilometers below us.
In this sense, the Swarm mission tries to measure the magnetic signals that come from the Earth's core, as well as other signals from the oceans or the Earth's crust, with the aim of obtaining information about the natural processes of the planet.
How is this new magnetic wave?
A recent article, published in the journal Proceedings of the National Academy of Sciences, tries to detail how a team of scientists has detected this new type of magnetic wave. "This mysterious wave oscillates every seven years and travels west at speeds of up to 1,500 kilometers a year."
"Geophysicists have long theorized about the existence of such waves, but they were thought to take place on much longer time scales than our research has shown," explains Nicolas Gillet of Université Grenoble Alpes and lead author. from the article. "We combined satellite measurements from Swarm, and also from the earlier German Champ mission and the Danish Ørsted mission, with a computer model of the geodynamo to explain what the ground-based data yielded, and this led to our discovery."
Due to the Earth's rotation, these waves line up in columns along the axis of rotation and the changes in motion and magnetic field are strongest near the equatorial region of the core.
"It is likely that the magnetic waves are caused by disturbances deep in the Earth's fluid core, possibly related to buoyancy plumes," adds Dr. Nicolas Gillet. The research suggests that it is possible that "other such waves exist, probably with longer periods, but their discovery depends on further investigation."