The geomagnetic field protects the Earth's atmosphere against charged particles from the solar wind. Rapid and long-term changes in the field are monitored by low-orbiting satellites and a global network of about 200 magnetic observatories. Field models, computed from these measurements, provide the direction and strength of the magnetic field at any desired location. Magnetometers (or a simple compass) can then be used to compute pointing directions, complementing the location information provided by the global positioning system (GPS).

Earth's magnetic field is used in a wide variety of applications.  It is used to despin satellites, explore natural resources, survey property boundaries, point antennas and solar panels, conduct research, study Earth's tectonic history, and to navigate on land, sea, and air.

Earth's Magnetic Sources:

• The main field from the Earth's core
• Core flow inferred from the secular variation of the magnetic field
• The lithospheric field caused by magnetized crustal rocks
• Motional induction in the oceans
• Tsunami-generated magnetic fields
• Ionospheric fields
• Magnetospheric fields

Outreach Materials:

• Historical main field change and declination
• Tri-fold Handout
• Poster 
• Geomagnetism story map by NCEI
• Geomagnetism story map by ESRI

Miscellaneous Teaching Material:

• GEOL/PHYS 6650 Geophysics Graduate Seminar: Geomagnetics
• A movie of the Earth's magnetic field at 430 km above sea level simulated from the Comprehensive Magnetic Model (CM4). Movie courtesy Nils Olsen, DTU.
• Geomagnetism FAQ from NCEI  
• Plane and spherical harmonic representations of the geomagnetic field by Stefan Maus
• Conductivity of the Ionosphere by Stefan Maus
• Equatorial Ionospheric Electrodynamics by Rod Heelis
• Magnetospheric Currents at Quiet Times by Robert L. McPherron
• Geospace Environment Modeling tutorials
• CEDAR Workshop Tutorials
• A four-part after-school geomagnetism activity jointly developed by CIRES and NCEI and funded by NASA.