During April we celebrate International Dark Sky Week from 13th – 20th of the month. The seasonal variations in brightness, from the long dark winter months to the long bright summer days, provided a reliable anchor against which flowers grew and insects flourished, simultaneously providing the foundations for the behaviour of all other life. From one day to the next the changes in the duration of light and dark were imperceptible. Within a day, the changes from light to dark were moderated only by passing clouds and perhaps the odd eclipse here and there lasting but a few minutes. Our eyes evolved to this slow pace of change.
