The Last of the Light

This is the title of a very interesting book I've been reading about twilight, that transitional interlude between sunset and darkness, the borderland between day and night. Like all borders it's often freighted with uncertainty and disquiet; it holds us in the balance between two states: safety and danger, clarity and opacity. In the natural world, diurnal activity slows and ceases while nocturnal life begins to stir. Small birds fall silent, farm animal settle for the night and flowers close up whereas badgers and bats and moths emerge to go about their business.

I didn't know that there are three 'official' stages of twilight: civil, nautical, astronomical. depending on the position of the geometric centre of the sun relative to the horizon. This image, taken a few minutes after sunset looking westwards from an upstairs window, shows civil twilight in which the sun has set but is no more than 6 degrees below the horizon. There still enough light to finish an outside job and put away your tools; car drivers must remember to switch on their head lights. The brightest stars and planets become visible to the naked eye.

After this comes nautical twilight (the sun slipping from 6 to 12 degrees below the now barely illuminated horizon) followed by astronomical twilight: the sun drops from 12 to 18 degrees below - at which point the last discernible afterglow vanishes and true darkness falls.

Complicated isn't it?  The book is a meditation upon the twilight period as it has been rendered and celebrated in thought, art and literature. I hope to find some more dusky images to blip as I pay more attention to the twilight world. Photographically it's quite a challenge though.