Geomagnetism
The scientific study of Earth's magnetic field, its internal origin in the liquid outer core, spatial variations, and temporal fluctuations.
Governing formula
B_geo = ∇ × A (Geodynamo Induction: ∂B/∂t = ∇ × (v × B) + η ∇²B)
SI unit
μT (Microteslas, ~30–60 μT at surface)
In depth
Earth's dipolar magnetic field is generated by a self-sustaining geodynamo driven by convective circulation of electrically conductive liquid iron-nickel alloy in the outer core. The field deflects cosmic rays and solar wind plasma, protecting Earth's atmosphere.
Examples in the real world
Compass needles aligning along geomagnetic field lines pointing toward Earth's magnetic poles.