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Conventional rendering of aurora in sRGB. The dominant color of most auroras is the green from atomic Oxygen (558nm). This is NOT the same as the twice-ionized oxygen line (O-III at 500nm), and the sRGB green primary is a closer match than the HOT green.
Boundary Waters Canoe Area photo by John Walsh |
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HOT rendering (simulated) Red however, is a different matter. Most auroral red is from an emission line (also from oxygen) at 630nm. While not as deep a red as the HOT red at 656, H-alpha is still a visually better choice. Some auroral light actually comes from H-alpha, a result of the solar wind protons (ionized hydrogen) working their way into the atmosphere.
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AUR rendering (simulated)
Here is one more interpretation. This was rendered using an RGB color space based on the three dominant wavelengths seen in auroras: 400nm (violet), 558nm (green), and 630nm (red). The green component is relatively unchanged from the sRGB version, but the red, while less intense, is also less orange, a deeper truer-red hue. |
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