Question

How do we prove that the earth itself is a magnet ?

Answer 1

Magnetism of earth or of any other planet is not because there is some heavy magnet buried in their core, but is because of the presence of molten magma revolving in its core. Its revolution acts as a dynamo with charged particles. rotation of this bulk of charges in the core causes magnetism.

hope this is the answer to your question.

Good luck!