Glossary of Common Terms
- Aurora
- Colorful lights in the sky caused by charged solar particles hitting Earth’s atmosphere, commonly seen near the poles.
- Kp Index
- A global scale (0–9) that estimates geomagnetic activity. Kp 5 or higher is often aurora-worthy.
- Bz
- The north-south direction of the interplanetary magnetic field. A negative (southward) Bz allows aurora to form more easily.
- Solar Wind
- A stream of charged particles from the Sun that fuels auroras when it interacts with Earth’s magnetosphere.
- Coronal Hole
- An opening in the Sun’s atmosphere that releases high-speed solar wind, often triggering geomagnetic storms.
- Geomagnetic Storm
- A disturbance in Earth’s magnetic field caused by solar wind, which can enhance aurora activity.
- Hemispheric Power
- A NOAA estimate of how much power is going into auroral activity in gigawatts (GW). Higher = more visible aurora.
- IMF
- Interplanetary Magnetic Field — the magnetic field carried by the solar wind. Its direction and strength influence aurora visibility.
- Bt
- The total strength of the interplanetary magnetic field. Higher values often indicate stronger aurora potential when paired with southward Bz.