“Astronomical Dawn” begins when the sun is less than 18 degrees below the horizon. That’s when sunlight starts to illuminate the upper atmosphere. “Nautical Dawn” is the time when bright stars are visible as well as the horizon. (The condition that allows to take “sights” of the stars with a sextant) Depending on weather, sun 10-12 degrees below the horizon. “Civil Dawn” sets in last, at 6 degrees. Now depending on latitude and how close to summer solstice, it might not become “night” at all.
There are water spiders, but they survive under water by weaving spider silk into a diving bell like contraption. They fill it with air by dragging little bubbles from the surface to their contraption one at a time.
From now on, far as Horace is cocerned, it’ll be “… just another manic monday …”