Disclaimer: This mixer is a simplified picture made to build intuition, not a precise physics simulation. Read its waves and numbers as a feel for how three lights add up, not as exact real world measurements.

Adding Lights Together

Now to the mixing itself. Bring red and green up together and where their waves overlap your eye reads the pair as yellow, ffff00, even though there is no yellow light anywhere, only red and green shining at once. Bring the blue light up as well and all three together come out as white, ffffff, which is why a screen showing plain white is quietly running all three of its lights at full. Take them all away and you are back to black. Green plus blue gives cyan, red plus blue gives magenta, and every shade in between is just those three dials set to different points.

That is exactly what the sky is doing during an aurora. The gases up there give off their own light, oxygen its greens and reds, nitrogen its blues and violets, and your eye adds the whole display together into the colors you finally see. The sky becomes one enormous additive screen, running on the same rules as the one in your pocket: a few lights, each at its own brightness, blended by your eye into a single picture. Once you start thinking in lights instead of paint, every color on a screen becomes a simple question: how bright do you make each one?

Where This Leaves You

That is the quiet engine behind every image you have ever watched glow on a display, and behind every aurora you have ever stopped to watch. No paint, no ink, just a handful of lights leaning on each other in the right amounts. To work with exact values, our color tool takes any hex code and breaks it down into its RGB, HSL, and other equivalents, so you can move between them with confidence.

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