Dennis Brooks

Earth's Magnetic Field Secrets

The goal of his brief book is to describe the external dynamo theory in nontechnical language. Some of the information used to introduce one subject will be used to introduce other subjects. This means that we will be discussing some of the information more than once. It will help students transition to new subjects and reinforce what they have already learned. It also helps to bring clarity to new terms for people who are studying and learning about Earth's magnetic field for the first time. The New Theory The goal of this picture-book is to introduce a new theory, which is called the External Dynamo Theory. Where the old theory suggests that the magnetic field is produced within the planet, the new theory suggests that the magnetic field is produced by a greater dynamo system. This system includes the planet, the magnetic field, and the Van Allen radiation belts as separate components that work together. This means that there is a huge difference between the two theories. Keep in mind that neither the old theory nor the new theory gives absolute proof regarding the source of Earth's magnetic field. Both of them are theories and nothing more. Where the old theory suggests that the magnetic axis is produced and projected from the planet's liquid outer core, the new theory suggests that the magnetic field is produced within a larger planetary dynamo system and the Earth is only a component of that system. Also, with the new idea, the fuel necessary to run the dynamo comes from the sun. The energy from the solar wind brings the system to life. With the external dynamo theory, the magnetic axis is not projected from the center of the planet; it runs through the planet. Also, the planet does not have to be perfectly aligned within the system. It can be centered on the magnetic axis or its center can be offset from the magnetic axis. Take a look at the Axis of Rotation image to understand how the two theories are different from each other.
66 printed pages
Original publication



    How did you like the book?

    Sign in or Register


    Dyah Candrarinihas quotedlast year
    When a compass needle is placed within the magnetic field, the needle will always line up perpendicular to the direction of the current flow and parallel with the magnetic axis.

On the bookshelves

Drag & drop your files (not more than 5 at once)