Apparent brightness: Wigton lights

 

The Wigton lights have been lovely this year. There were stars hanging from the strings across the street. These were all identical stars but illustrate one point about the brightness of the stars we see in the sky. Here in Wigton we can see the distances between these stars but we can't tell when we look into the night sky. Everyone understands instinctively that if something is further away but intrinsically the same, it will appear to be dimmer to the observer. It follows an inverse square law: doubling the distance means there is a surface 4 times as big over which to spread the light energy. The brightness is therefore reduced to 1/4 of what it was.