Secrets of the Earth's Magnetic Field Author:Dennis Brooks Researchers first thought a huge magnet ran through the planet. Next, they thought there was a dynamo in the inner core. Then, they thought a dynamo might exist in the outer core of the planet. Recently, scientists have been studying the dynamo that is found with every planet that has a magnetic field. This research has shown that the ou... more »ter dynamo system is the source of the magnetic field. The magnetic field of each planet (Earth, Jupiter, Saturn, Uranus, and Neptune) is produced by the ring currents in the radiation belts. Each planet is a component of the dynamo system that produces the magnetic field.« less