The gradient moves through ten palette stops based on real solar altitude — astronomical night, nautical and civil twilights, golden hour, low sun, midday, and everything in between. A sun arcs across during the day, a moon takes the anti-sun position at night, and stars fade in below civil twilight.
All solar math runs locally using NOAA's simplified algorithm — no API calls, no network dependency, no keys. Works for any latitude / longitude, including polar day and polar night.
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