Finding your location…
Checking the sky
- Kp
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- Hp30
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- Solar wind Bz
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- Wind speed
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- Peak Kp, 24h
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- Cloud
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What do these numbers mean?
- Kp
- The standard 0 to 9 measure of how disturbed Earth’s magnetic field is, updated every three hours. Around 5 or more is a geomagnetic storm, and the higher it goes the further south aurora can be seen.
- Hp30
- Kp’s finer cousin from GFZ Potsdam: the same idea measured every 30 minutes, so it reacts faster, and it can go above 9 in extreme storms.
- Solar wind Bz
- The north-south direction of the magnetic field carried in the solar wind. When it points south (negative, ideally below −5 nT) it connects with Earth’s field and feeds the aurora. Positive values tend to shut things down.
- Wind speed
- How fast the solar wind is passing the satellite, in km/s. Around 400 is calm; 600 or more drives stronger displays.
- Peak Kp, 24h
- The highest Kp over the last day, a quick way to see whether tonight is quiet or a storm has just passed.
- Cloud
- Forecast cloud cover over your spot right now. Under about 30% is good for looking; over 80% hides the sky.
Solar wind readings come from a satellite about 1.5 million km sunward, so they lead what reaches Earth by roughly 30 to 60 minutes.
Next 24 hours
UnlikelyPossibleGoodStrong
What is this?
Taller and brighter means a better chance. Glowing bars are the best window. Tap a bar for the hour’s score and cloud. Assumes current solar activity holds.
What decides tonight
What is this?
A sighting needs three things at once: solar activity strong enough to push the aurora down to your latitude, a properly dark sky, and gaps in the cloud. Whichever is weakest sets your chances.
How strong a storm you need
What is this?
Live aurora activity
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What is this?
Ground magnetometers across northern Scandinavia. When the field drops sharply, a substorm is under way and the aurora is brightening, often within minutes. Readings are the biggest dip in the last hour against the quiet level before it.
Looking ahead
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What is this?
Where the next storm could come from. Flares and the forecast are estimates and change daily.
UK and Ireland cloud cover
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What is this?
Where it is clear enough to look right now. Open-Meteo.
Track record
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