The sun's geometry
Solar altitude
Solar altitude is the sun's height above the horizon in degrees, from 0° at sunrise to 90° overhead.
Every hour of light Sol names — golden, blue, the twilights — is a band of altitude, not a time.
Golden hour, the twilights and the moon, where you stand.
Sol for iPhone is coming soon, with each of them for the place you stand, on your phone and your wrist.
Solar altitude, where you stand.
You stand at the middle of your horizon. The dots are the sun’s path today, warm where the light turns golden; the stage opens at this minute. Slide through the day, or drag the sky to turn it.
How Sol measures it.
Sol computes it from your latitude, longitude, the date and the minute, to about a tenth of a degree, the same way for every instrument. The drawing is the altitude scale the twilights are defined on; the dot is the sun now. Refraction near the horizon lifts the apparent sun a little, and the twilight definitions use the geometric altitude.
Make time for the light.
Sol for iPhone is coming soon, with golden hour, the twilights and the moon for wherever you stand. Leave your address for early access and one email when it ships.
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