Notre planète est fascinante, mais elle recèle encore bien des mystères. Une mission de l’ESA baptisée Swarm devrait nous aider à mieux comprendre le champ magnétique de la Terre, qui intrigue encore la communauté scientifique. La mission Swarm est composée de trois satellites. Leurs derniers résultats viennent d’être dévoilés!
Earth’s magnetic field is mostly created by incredibly hot liquid iron that moves around our planet’s core. Magnetised rocks in Earth’s crust also have a small effect. Did you know that seawater is also a source of magnetism? When salty seawater flows through Earth’s magnetic field, an electric current is generated, and this in turn creates a magnetic force. It is very small and incredibly difficult to measure, but the Swarm satellites have done just this.
Mapping magnetic fields from the ocean surface to the seabed has allowed scientists to discover how the water is flowing at all depths, which is completely new information. Oceans absorb heat from the air, so tracking how heat is spread throughout the oceans is an important part of understanding more about Earth’s climate. The latest Swarm mission results are even helping us to learn about the electrical properties of Earth’s crust, and just below it – an area called the lithosphere. In fact, Swarm has made a new map of the magnetic field generated by Earth’s crust!
Swarm a observé l'évolution de notre champ magnétique sur 24 heures. Les zones rouges mettent en évidence les signaux magnétiques les plus intenses. Copyright : © Planetary Visions (crédits : ESA/Planetary Visions).
All this is important because Earth’s magnetic field protects us from harmful radiation in space, is part of our climate, and can reveal secrets about the inside of our planet. So the more we discover about our magnetic field, the more we learn about our home planet.
Fait intéressant : the three Swarm satellites are called Alpha, Bravo, and Charlie.
