Using information from ESA’s Swarm satellite mission, scientists have discovered a completely new type of magnetic wave that sweeps the outermost part of the Earth’s outer core every seven years. This fascinating find opens a new window into a world we will never be able to see. This mysterious wave oscillates every seven years and spreads westward up to 1500 kilometers (900 miles) a year. Credit: ESA / Planetary Visions
While volcanic eruptions and earthquakes serve as immediate reminders that the Earth’s interior is anything but peaceful, there are also other more elusive dynamic processes that take place in the depths of our feet. Using information from ESA’s Swarm satellite mission, scientists have discovered a completely new type of magnetic wave that sweeps the outermost part of the Earth’s outer core every seven years. This fascinating find, presented today at ESA’s Living Planet Symposium, opens a new window into a world we will never be able to see.
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 gravitational pull of the Sun and flow through the Solar System. Without our magnetic field, life as we know it could not exist.
Swarm constellation. Credit: ESA / ATG Medialab
Understanding exactly how and where our magnetic field is generated, why it is constantly fluctuating, how it interacts with the solar wind, and, in fact, why it is currently weakening, is not only of academic interest but also of benefit to society. For example, solar storms can damage communication networks and navigation and satellite systems, so while we can’t do anything about changes in the magnetic field, understanding this invisible force helps us to be prepared. .
Most of the field is generated by an overheated and swirling liquid iron ocean that forms the outer core of the Earth 3000 km (1900 miles) below our feet. Acting like the driver spinning on a bicycle dynamo, it generates electric currents and the electromagnetic field that changes continuously.
ESA’s Swarm mission, which consists of three identical satellites, measures these magnetic signals from the Earth’s core, as well as other signals from the crust, oceans, ionosphere, and magnetosphere.
Since the launch of the Swarm satellite trio in 2013, scientists have been analyzing their data to gain a new insight into many of the Earth’s natural processes, from space climate to physics and the dynamics of the heart. stormy Earth.
Using information from ESA’s Swarm satellite mission, scientists have discovered a completely new type of magnetic wave that sweeps the outermost part of the Earth’s outer core every seven years. This fascinating find opens a new window into a world we will never be able to see. This mysterious wave oscillates every seven years and spreads westward up to 1500 kilometers (900 miles) a year. Credit: ESA / Planetary Visions
Measuring our magnetic field from space is the only real way to explore the Earth’s core in depth. Seismology and mineral physics provide information on the material properties of the core, but do not shed light on the dynamo-generating motion of the liquid outer core.
But now, using data from the Swarm mission, scientists have discovered a hidden secret.
An article, published in the journal Proceedings of the National Academy of Sciences, describes how a team of scientists detected a new type of magnetic wave that sweeps the “surface” of the Earth’s outer core, therefore, where the core meets the mantle. This mysterious wave oscillates every seven years and spreads westward up to 1500 kilometers (900 miles) a year.
Nicolas Gillet, University of Grenoble Alpes and lead author of the article, said: “Geophysicists have long theorized about the existence of these waves, but they were thought to take place on much longer time scales. longer than our research has shown.
“Magnetic field measurements of instruments based on the Earth’s surface suggested that there was some kind of wave action, but we needed the global coverage that measurements offer from space to reveal what’s really going on. .
“We combined Swarm satellite measurements, as well as the previous German mission and the Danish Ørsted mission, with a geodynamic computer model to explain what the terrestrial data had generated, and this led to our discovery. “.
Due to the rotation of the Earth, these waves line up in columns along the axis of rotation. The motion and magnetic field changes associated with these waves are stronger near the equatorial region of the core.
Although the research shows magneto-Coriolis waves for a period of about seven years, the question of the existence of these waves that would oscillate in different periods, however, remains.
Dr Gillet added: “Magnetic waves are likely to be triggered by perturbations in the depths of the Earth’s fluid core, possibly related to buoyancy plumes. Each wave is specified for its period and typical length scale, and the period depends on the characteristics of the forces at play.For magneto-Coriolis waves, the period is indicative of the intensity of the magnetic field within the nucleus.
“Our research suggests that other such waves are likely to exist, probably with longer periods, but their discovery is based on further research.”
ESA Swarm Mission scientist Ilias Daras noted: “This current research will undoubtedly improve the scientific model of the magnetic field inside the Earth’s outer core. It can also give us a new view of conductivity. of the lower part of the mantle and also of the thermal history of the Earth “.
Reference: “Magnetic satellite data reveals interannual waves in the Earth’s core” by Nicolas Gillet, Felix Gerick, Dominique Jault, Tobias Schwaiger, Julien Aubert and Mathieu Istas, March 21, 2022, Proceedings of the National Academy of Sciences.DOI: 10.1073 / pnas.2115258119
With the support of ESA’s Science for Society program, this research was presented at ESA’s Living Planet Symposium this week in Bonn, Germany. Attendees are listening to the latest scientific findings on our planet and how observation from Earth from space supports environmental research and action to combat the climate crisis. They are also hearing about new space technologies and the new opportunities that are emerging in the rapidly changing Earth observation sector. Selected sessions are being streamed live, see ESA Web TV channels.