The sun's mood
A dial for the magnetic field, a map of where the lights are likely, and the solar wind rushing past the satellites that watch the sun.
0 viewsThe planetary K index, a measure of how disturbed Earth's magnetic field is, was 2.67 at the last reading. Under 5 is quiet.
Drawing the latest figures…
Questions people ask
What is the K index?
A number from 0 to 9 for how restless Earth's magnetic field has been over the last three hours. Around 5 or higher, the northern lights can be seen further south than usual.
Is the green on the map a photograph of the lights?
No. It is a forecast of where an aurora is likely, made from the solar wind that has just arrived. Brighter green means a higher chance, not a picture taken from the ground.
Space weather: NOAA Space Weather Prediction Center, public domain.
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