Geomagnetic Storm
A major temporary disturbance of Earth's magnetosphere caused by solar wind shockwaves or Coronal Mass Ejections (CMEs).
Governing formula
Dst Index < -50 nT (Distortion of Equatorial Ring Current)
SI unit
nT (Nanoteslas, Dst / Kp Index)
In depth
Enhanced magnetic reconnection injects energetic plasma into Earth's magnetosphere, intensifying the equatorial ring current and causing global geomagnetic field disruptions, power grid surges, and expanded auroral displays.
Examples in the real world
The Carrington Event of 1859 inducing widespread telegraph line sparks and bright tropical auroras.