The lying sky

6.00 AM a couple of days ago. I've been lying awake for an hour. I get up, toddle downstairs and glance out of the patio doors. In Glasgow at this time of year the Sun rises about 8.45 so it's still dark. I step outside to a clear, starry sky. It's cold but beautiful. Just west of the meridian the stars of Leo have begun their slide to the horizon. To its east Arcturus glares down balefully. Further round towards the north-west are stars of winter: Castor and Pollux, Procyon, Capella. Sometimes in our suburban skies you can spot the star cluster Praesepe, highlight of dull wee Cancer but this morning there's slightly too much glow in the sky.

This photo was taken on late on a February evening in 2014. The constellation Leo is to the left, Gemini to the right. Jupiter lies in Gemini on this date, the brilliant starlike object at the far right. You can spot the little smudge of Praesepe in between these two brilliant constellations. None of its stars is bright enough to spot easily with the naked eye but there are enough of them that the whole thing is visible as a "smudge". Equally evident, less charming is the general red glow of light pollution all through the sky.

Feeling cold I go inside and make a cup of tea. I pad about a little then step outside again, still nursing my tea. A few steps further away from the house I can turn round, spot the Plough overhead, Lyra and Cygnus round to the north. It's still dark and splendid but there's now a hint of morning glow to the south-east. I'm suddenly sad that the sky will soon lighten and this panorama will disappear.

In the night sky we're brought face to face with our immense, ancient universe. Each star is a Sun like ours, some of them enormous by comparison, all so distant that they're reduced to mere twinkling points of light. If the Universe were infinite and stars stretched to infinity the night sky would be filled with light. Instead we see individual stars with dark spaces in between. So the darkness of the night sky points our thinking to a universe that has not existed forever, that began at a finite time in the past. Each of us, a once-only project, only makes sense in the context of this once-only Universe. Under the night sky we think more deeply about our fundamental nature.

But then the Sun comes up. Its light floods the daytime sky, the stars are hidden and we see only our immediate surroundings. Our thoughts are directed away from our cosmic context and the essentials of our physical nature to the immediate: people we despise or desire, jobs, booze, sport, politics. Clothes and furniture. The daytime sky is a bright, cheery liar.