Answer: magnetic substances
Step-by-step explanation:
The magnetic field of Earth and several other planets are produced by magnetic substances such as Iron and nickel present in the molten form in their core. With their motion, the domains of the magnetic material align in a single direction generating huge magnetic field.
The magnetic field helps protect from high speed solar particles and helps in navigation. Auroras are caused due to magnetic fields. Auroras can be seen of Earth, Saturn, Jupiter indicating that these planets have magnetic fields.