Current Conditions
24-Hour Trends
Solar Imagery & Aurora
Space Weather Alerts
What the numbers mean
Planetary K-Index (Kp)
The global geomagnetic storm index, on a scale of 0-9.
In Ohio you generally need a Kp of 6 or 7+ to see the aurora overhead. Kp 5 might give you a faint glow on the northern horizon.
Interplanetary Mag (Bz)
The north-south part of the solar wind's magnetic field, measured in nanotesla (nT).
You want it negative (pointing south). A negative Bz links up with Earth's northward magnetic field and lets solar energy pour in. -10 nT or lower is what you want for a strong aurora.
Total Field (Bt)
The total strength of the interplanetary magnetic field, whatever direction it points.
A higher Bt means a stronger magnetic structure is hitting Earth, but Bt alone doesn't cause aurora. You still need a negative Bz. Think of Bt as the potential and Bz as the trigger.
Solar Wind Speed
How fast the solar particles are moving.
Look for 500 km/s+. Faster wind hits Earth's magnetic field harder, and the aurora gets brighter and more active.
Solar Wind Density
How many particles are packed into the solar wind.
Look for 10 p/cm³+. Denser wind means more fuel for the aurora and often sets off sudden bursts.
Proton Events (10MeV Integral Flux)
A solar radiation storm, caused by energetic protons reaching Earth.
A warning like "exceeded 10000pfu" means a strong radiation storm (S3 level). It can cause radio blackouts and trouble for satellites, but it does not directly cause aurora you can see in Ohio. It does tell you the Sun is very active.