small magnetometers

Small magnetometers like these measure magnetic strength on Earth and in the atmosphere to determine how much of the Sun's magnetic energy has been transferred to Earth's magnetosphere. Images credit: Glassmeier, et al.

A magnetometer is a device for measuring the strength and direction of a magnetic field. Magnetometers typically detect the strength of magnetic fields in three planes. Various types exist, exploiting, for instance the oscillation rate of a small, freely suspended bar magnet or the deflection of a magnet against its suspension or a reference field.


The simplest type consists of a short, bar magnet with a nonmagnetic pointer attached to its center so that it is at right-angles to the axis of the magnet. The magnet is pivoted, like a compass needle, at its center and the pointer travels over a calibrated scale.


Sensitive magnetometers used in space research include the proton precession magnetometer and the helium magnetometer.