Frank Rigel Sky

From the Old French franc, free, sincere — used as a color modifier since the seventeenth century for hues that read as direct and unhedged. Frank red, frank brown: moderate-to-high saturation combined with optical directness. Sits at the crisp-bucket alongside direct and honest.

Arabic rijl-al-jawzā', foot-of-Orion. As a color modifier, rigel implies a blue-supergiant-and-Orion-foot quality, the visual register of Orion-Hunter-and-winter-blue-supergiant-Rigel hand-blue-supergiant-and-Orion-foot Orion-Hunter-and-winter-blue-supergiant-and-Bortle-1 rigel-and-blue-supergiant-and-winter-zenith surfaces under Orion-Hunter-and-winter-blue-supergiant-and-Bortle-1 January-and-February-winter-Orion deep-blue-stellar-light. Sits at the modifier-and-cosmic end of the grid, parallel to vega and deneb in usage.

The blue of a clear sky at noon — produced by Rayleigh scattering, the preferential dispersion of shorter wavelengths through atmospheric molecules. Air itself is colorless; the color we see is sunlight scattered toward our eyes by every cubic kilometer above. The reference shade is mid-latitude noon under a high pressure system: a clean, slightly green-shifted blue with the luminous depth of light scattered across an entire hemisphere of air.