geomagnetism
nounUK /ˌdʒiːəʊˈmæɡnətɪzəm/
US /ˌdʒiːoʊˈmæɡnətɪzəm/
Geomagnetism is the magnetic force that the Earth makes, like a giant hidden magnet inside our planet.
Sailors have used geomagnetism for centuries to help their compasses point north.
OTHER MEANINGS
2. The scientific study of the Earth's magnetic field and how it changes over time.
She studied geomagnetism at university to understand why the magnetic poles slowly move.
3. The branch of geophysics that measures and maps magnetic patterns in rocks and the ground.
Geomagnetism helps geologists find iron ore buried deep underground.
4. The natural magnetic properties of Earth that affect navigation and animal migration.
Birds and sea turtles may sense geomagnetism to find their way across oceans.