Welcome to the world of geomagnetism! This website aims to introduce the science of Earth’s magnetic field to students and new researchers. It is currently in the early stages of development - if you are interested in contributing or have any comments, see About this site


Background colour: magnetic field intensity (magnitude) in nanoTesla
Red/blue contours (hover tooltip): magnetic field declination (deviation from true North) in degrees

What is geomagnetism?

Geomagnetism is the study of Earth’s magnetic field. While the vast majority of the field resembles a dipole, similar to a bar magnet, sensitive measurements reveal that its shape is more complex and in fact originates from the combination of multiple field sources. These sources range from within Earth’s outer core, the crust (where we live!), atmosphere, and magnetosphere. The magnetic field varies over time in both predictable and unpredictable ways, which makes it an interesting area of study and has several applications within industry.

Geomagnetists study Earth’s magnetic field by processing measurements from observatories, surveys, and satellites, as well as palaeomagnetic signatures stored in dated rocks. They also gain insight into physical processes through laboratory experiments and computational simulations. However, almost everyone has measured the magnetic field direction themselves using a compass, with the first recorded evidence of compasses in the 11th Century A.D. in China. Today, a typical mobile phone contains a magnetometer and software which uses a geomagnetic model to help pinpoint your location and orientation.

Variations in the magnetic field are connected with geophysical processes both below Earth’s surface and out into space, providing a tool to probe Earth’s structure and composition as well as being implicated in phenomena such as the aurorae (the Northern and Southern Lights). Modern geomagnetic measurements are highly sophisticated and are connected with several industrial applications beyond navigation, including exploration geophysics, and operation of spacecraft and power grids.

Other introductions to geomagnetism can be found at: