宇宙天気

The Kp index (0–9) measures geomagnetic disturbance — values above 5 indicate a geomagnetic storm and possible aurora visibility at mid-latitudes. X-ray flux shows the current solar flare class (A < B < C < M < X), where M- and X-class flares can disrupt radio communications. Solar wind speed (typically 300–400 km/s) and proton density drive geomagnetic effects when elevated. The sunspot number tracks the solar cycle; higher counts correlate with more frequent flares and storms. NOAA scales summarize current conditions: R (radio blackout), S (solar radiation), G (geomagnetic storm), each rated 0 (quiet) to 5 (extreme).

Aurora (polar lights) visibility depends on geomagnetic activity and your latitude. The Kp index determines how far south the aurora oval extends. A strongly negative Bz (southward interplanetary magnetic field) opens Earth's magnetosphere, making aurora more likely. High solar wind speed and density amplify the effect.