The Earth's Magnetic Field

If a magnet is suspended so it can rotate, it will always turn until the north pole of the magnet points north. It does this because the Earth has a magnetic field and the magnet lines itself up with the Earth's field.

A compass needle is a magnet and the compass points to the north for the same reason.

The magnetic field pattern of the Earth is the same as the field of a bar magnet, as shown above. The Earth has a core of molten iron and it is this that gives rise to the magnetic field.