Geomagnetism is the invisible force field that surrounds Earth and makes compasses point north. It is Earth's magnetic field.
As Earth spins, molten metal deep within the planet constantly flows and circulates. The flowing metal conducts electricity, generating a magnetic field that extends into space and surrounds the planet. Geomagnetism helps protect Earth by deflecting a stream of charged particles from the Sun (known as the solar wind). It's important for navigation, as it's the reason compasses point north, and it allows migratory animals that can sense the field — such as birds and sea turtles — to find their way around the globe.