Sometimes I get up early enough to watch the sunrise. Usually deliberately though usually not “naturally” — I will set an alarm so that I can meet the day, literally. Most often I do this during the fall or winter when, not as now in mid-summer, sunrise is at a “reasonable” time. More like 6 or 7AM instead of more like 5AM.
In researching the correct time for this alarm I learned “sunrise” is not what I thought it was. I would check the internet for tomorrow’s sunrise time, get up, and find the sky was already bright. How had I missed it?
It turns out that if I wanted to watch night give way to day, what I was really looking for was one of the dawns. There are three of them, and though I enjoy all three, the time I was looking for was the last: “Civil Dawn”.
Each day begins with three dawns, and three twilights. Astronomical, Nautical and Civil. Each dawn is an exact time. The dawns mark the moments the geometric centre of the sun is a particular number of degrees below the horizon (18°, 12° and 6° respectively). And each dawn is followed by its twilight, again Astronomical, Nautical and Civil. The end of this dance is sunrise. The same twilights happen in reverse order each evening, but beginning with sunset, and with three dusks replacing the three dawns. (To learn more — read here.)
Astronomical twilight is still a dark-dark. Black as night. But it is when the sun is nevertheless too near the horizon for us to see some astronomical features — it’s when the brightness of our sun obscures some of the other stars.
Nautical twilight is the time for sailors. When the sky is bright enough to be able to see where the sea meets the sky, but still dark enough that the stars used for navigation are visible in the night/day sky.
Civil twilight is the time for me. When it is not “bright as day”, but “bright enough” — bright enough that we lunky bi-pedal bi-nocular apes are able to get around without artificial light.
Civil dawn and civil twilight is a fascinating time to have your eyes open, and be navigating the world. As the moments pass, you can nearly feel your irises stretching open to take in each new spec of light. The world brightens around you. The sun is turning on the lights.