Planetary MagnetsPlanets have magnetic fields generated deep inside themselves.
The Earth is a good example of a planetary dipole. Planets can also show evidence of quadrupoles (4 poles) and octupoles (8-poles). Jupiter and Saturn are good examples of multi-pole planetary magnetism.
Not every planet has a magnetic field. It takes special conditions to generate a magnetic field within a planet. Scientists are fairly certain that there are two essential ingredients for generating a magnetic field. Those two ingredients are magnetic material and currents moving inside the magnetic material.
Other planets known to have a magnetosphere include Mercury, Mars, Jupiter, Saturn, Uranus, and Neptune. Venus is a special case of a rocky planet with no magnetic field.