The words of light. Each defined once.
Thirty terms the instruments use — one sentence, one drawing, and the instrument that measures it, for where you stand.
The light
Golden hourwarm, low sun Blue hourthe deep blue after sunset Afterglowcolour after the sun has gone Alpenglowpink peaks after sunset The Belt of Venuspink over the Earth's shadow The sunset forecastlittle, some, good, exceptionalThe twilights
Civil twilightsun 0° to 6° below Nautical twilightsun 6° to 12° below Astronomical twilightsun 12° to 18° belowThe day
Dawnthe light before sunrise Duskthe light after sunset Sunrisethe upper edge appears Sunsetthe upper edge goes Solar noonthe sun at its highest Day lengthsunrise to sunset First lightcivil dawn Last lightcivil duskThe sun's geometry
Solar altitudethe sun's height, in degrees Azimuththe sun's compass bearing The sun's paththe day's arc across the sky Shadow lengthheight over the tangent The equinoxday and night nearly equal The solsticethe longest and shortest days The 37° linewhere the sunny side switchesThe moon
Full moonopposite the sun, all night New moonbetween us and the sun The phase of the moonhow much of the face is lit Moonrise and moonsetabout fifty minutes later each day Supermoona full moon at its nearest Blue moonthe second full moon in a monthMake time for the light.
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