How the Visibility Score Works
A single number — 0–100% — that tells you how likely you are to see the aurora right now. Here's what goes into it.
📊 What Is the Visibility Score?
The AuroraVision visibility score combines multiple real-time space weather and atmospheric data sources into a single percentage. A score of 0% means no aurora, 100% means ideal conditions for a spectacular display.
The score updates every ~2 minutes from live NOAA data — the same data used in the AuroraVision mobile app.
⚗️ The Formula
The score is weighted as follows:
Bz — 45%
The most important factor. Negative Bz (southward magnetic field) opens the door for solar particles to enter Earth's magnetosphere. The more negative, the better.
Solar Wind Speed — 25%
Faster wind means more energetic particles hitting the atmosphere. Speeds above 400 km/s start to matter; above 700 km/s is excellent.
Bt (Field Strength) — 15%
Total interplanetary magnetic field strength. Higher Bt, especially when south-pointing, amplifies the aurora effect.
Particle Density — 5%
The number of particles per cubic centimetre in the solar wind. More particles = more energy delivered to the ionosphere.
Cloud Cover — 10%
Even perfect space weather is useless if it's cloudy. High cloud cover significantly reduces the score, since you won't be able to see anything.
Aurora Power Bonus
If NOAA's OVATION model shows high aurora power directly over your selected location, a +10% bonus is applied.
🔢 Score Interpretation
0–20% — Poor
Very unlikely to see aurora. Quiet solar conditions or too much cloud cover. Not worth going out tonight.
21–40% — Low
Marginal conditions. Aurora possible but faint. Worth checking cloud cover — might be worth a quick look if skies are clear.
41–60% — Moderate
Decent conditions. A visible display is likely if you're away from city lights and the sky is clear.
61–80% — Good
Good conditions. The aurora should be clearly visible. Get outside and find a dark spot.
81–100% — Excellent
Go outside NOW. Exceptional conditions — dramatic display, multiple colours, possibly visible from city centres.
📡 Data Sources
All space weather data comes directly from NOAA (National Oceanic and Atmospheric Administration) real-time feeds:
- Solar wind (Bz, Bt, speed, density): NOAA ACE/DSCOVR spacecraft — 1-minute cadence
- Kp index: NOAA planetary K-index — 1-minute estimates
- Aurora oval power: NOAA OVATION model — updated every 30 min
- Cloud cover: Open-Meteo API — based on ECMWF weather model
📱 Same Formula as the App
The visibility score on this website uses the identical formula as the AuroraVision mobile app. The app adds push notifications — so you get alerted automatically when conditions cross your threshold, without needing to check the website manually.
Get notified when it's actually worth going outside.
Set your alert threshold. AuroraVision wakes you up when the score is high.
