Dusk In My Back Yard.
Civil dusk is the time at which the sun is 6 degrees below the horizon in the evening. At this time objects are distinguishable and some stars and planets are visible to the naked eye.
This marks the end of the evening civil twilight, the point where artificial illumination is required to read outside. Twilight comes after sunset, which is the point at which the earth has rotated just enough that the sun is no longer visible on the local horizon (under clear conditions).