Twilight Times: Civil, Nautical and Astronomical

May 29, 2020


Photographer: Marco Meniero
Summary Authors: Marco Meniero; Jim Foster

The photos shown above demonstrate how the amount of light changes during the progression of twilight. They were taken at the Viterbo Airport Control Tower in Italy, on May 8, 2020. I pointed the camera optics towards the town of Montefiascone, which from my position is to the north. The first photo, at lower left, was taken at 13:00 or 1:00 p.m. (local time), then in counterclockwise order at 8:19 p.m. (sunset and beginning of the civil twilight), at 8:50 p.m. (beginning of nautical twilight) and at 9:29 p.m. (beginning of astronomical twilight). Once the Sun dips more than 18 degrees below the horizon, twilight brightness approaches zero -- considered the beginning of nightfall.