What Are Northern Lights Colors? (Live Spectrum Analysis)
Most people think the Northern Lights are just green. If you look at a standard photo, that is usually what you see. But if you are lucky enough to witness a powerful geomagnetic storm, the sky can explode into a rainbow of Crimson Red, Neon Pink, and Deep Purple.
But here is the secret: The colors aren’t random.
The colors you see depend entirely on two things: Altitude and Gas Composition. Think of the atmosphere like a layer cake. Different gases live at different heights, and they glow in different colors when hit by solar particles.
We developed the Live Spectral Analyzer below. It reads real-time solar wind data (Speed and Density) to calculate which atmospheric layers are being hit right now, and predicts which colors are likely visible to the human eye.
The Science: Why Do These Colors Happen?
To understand the colors, you have to understand the collision. The Northern Lights are essentially a neon sign on a planetary scale. Solar particles smash into atoms in our atmosphere, exciting them. When the atoms calm down, they release a photon of light.
1. Green (The Standard)
Element: Oxygen
Altitude: 100km – 150km
This is the most common color. Our eyes are most sensitive to green light, and Oxygen at this altitude is abundant. It takes a “standard” amount of energy to excite these atoms. If the Kp index is 2 or higher, you will almost certainly see green.
2. Pink & Purple (The High-Speed Hammer)
Element: Nitrogen
Altitude: Below 100km
This is the “Holy Grail” for aurora chasers. Nitrogen is a heavy molecule that lives low in the atmosphere. To get the aurora to glow pink, the solar wind particles need to be moving incredibly fast (usually >500 km/s) to punch through the upper layers and smash into the Nitrogen at the bottom.
Check the “Pink” bar in the tool above. If it is high, look for a purple fringe at the very bottom of the aurora curtains.
3. Red (The High Altitude Ghost)
Element: Oxygen
Altitude: Above 200km
Red is actually very common, but it is often too faint for the human eye to see. It happens at the very edge of space. Because the air is so thin up there, the red light is easily drowned out by the brighter green below it. However, during massive storms, the entire sky can turn blood red. This was historically seen as a bad omen!
How to Photograph the Colors
Your eyes are not as good as your camera sensor. At night, human eyes struggle to see color (we mostly see in black and white). You might see a greyish-white cloud, but your camera will see vibrant green and pink.
To capture the full spectrum:
- White Balance: Set to 3500K – 4000K. If you leave it on Auto, the camera might try to “correct” the purple nitrogen glow and turn it blue.
- Exposure: Keep it under 5 seconds. If you expose for too long, the movement of the aurora will blend the colors together, turning the distinct pink bottom into a muddy white.
- Look North: But also look Up. The Red aurora often appears directly overhead (the Corona), while the Pink appears at the bottom of the arcs on the horizon.
