The magnetic field of the Earth, or the geomagnetic field, as measured at ground based observatories is a combination of contributions from the earth's crust and liquid core, as well as electric current systems surrounding the Earth. Observatories around the world continuously monitor the geomagnetic field to provide the foundation for understanding the nature and origin of these contributions.
Australian observatories are particularly important in a global context.
They are among the few observatories in the southern hemisphere, and have acheived long records of continous observations. The observatory set up in Hobart in 1840 by the polar explorer James Clark Ross, at the behest of the British Government, was one of the first magnetic observatories to be established in the world.