Twilight Fully Involved Sky
Some of the pre-sunrise drives out into the backcountry are silly amazing sometimes. It takes me a minute to get set up for this kind of location. I usually have photographed the sight a different day . This fully involved twilight sky was colorful icing on the cake from that morning’s long timeline.
The term “Twilight” means 3 different things: Civil Twilight begins about 28 minutes before sunrise or ends 28 minutes after sunset. It is that period from when the sun is about 6 degrees below the horizon. On clear days you can do normal outside activities that require light. That solar elevation angle below the horizon defines each twilight phase. CIvil Twilight is by far the brightest of the three twilights.
Nautical Twilight starts when the sun is 12 degrees below the horizon technically. Both the Horizon AND brighter stars/planets are visible in this twilight. It is the “middle” of the three twilights. At the beginning of Nautical twilight, it’s about one hour to sunrise.
Rule of thumb which varies with your position on the globe, is 28 minutes each twilight. In Astronomical Twilight, If you live in the city, you have probably never noticed astronomic twilight. The are NO shimmers of daylight at the beginning of Astronomic Twilight a full hour and a half before sunrise. .
Away from the lights of population centers, we see Astronomic Twilight regularly where there is just a slight greying of the black totally dark sky mid night. It gets as dark here on our ranch in remote northeastern Wyoming as the North Atlantic Ocean according to NASA.
Location: Bliss Dinosaur Ranch, Wyoming/Montana borderlands.
Twilight Fully Involved Sky