What is astronomical twilight?

[Admin]

Astronomical twilight is the darkest phase of twilight that a viewer sees before the last refracted sunlight leaves the horizon. It usually occurs twice a day.

What is astronomical twilight? : Read more

 

[billslugg]

Civil twilight - everyday outdoor activities cease
Nautical twilight - can no longer see the horizon to get a sextant reading
Astronomical twilight - last light