The Aurora Process
Four steps from solar surface to Icelandic sky
The KP Index Explained
The Planetary K-index (Kp) measures global geomagnetic activity on a scale from 0 (very quiet) to 9 (extreme storm). It is derived from magnetometers at 13 stations worldwide and updated every 3 hours.
Aurora Glossary
Oxygen at 100–150 km altitude. The most common aurora color, produced when oxygen atoms are excited by colliding particles and emit green photons as they de-excite.
Oxygen at 200+ km altitude. Rarer and typically only seen during strong geomagnetic storms when particles penetrate to very high altitudes.
Nitrogen molecules at lower altitudes below 100 km. Often visible as a distinct blue-purple fringe at the bottom edge of green aurora curtains.
A mixture of green and red oxygen emissions at overlapping altitudes. Appears white or yellow when multiple emission layers blend together.
Why is aurora only visible at night?
Sunlight is far brighter than the faint glow of aurora. You need full astronomical darkness — typically 90+ minutes after sunset — for your eyes to dark-adapt and the aurora to become visible against the sky.
Can aurora happen in summer?
Not visibly in Iceland due to the midnight sun (May–August). Solar particles still arrive and collisions still happen, but Iceland's sky never gets dark enough for aurora to be seen. Season runs September to April.
Why does aurora 'dance'?
Variations in the solar wind — changes in speed, density, and magnetic field direction — cause Earth's magnetic field lines to shift and vibrate. Aurora attached to those field lines moves, ripples, and dances in response.