Today, in the 21st century, a valuable and beautiful part of our heritage is being taken away from us. For the first time in history, vast numbers of the human population are being denied a view of the night sky by poorly designed and badly aimed lighting of various kinds. Urban sky glow now pollutes nearly all of the British Isles' night skies. Is there any hope of regaining natures grandest free show?
Artificial light gets up into the sky in two ways. By far the greater proportion of this upward light arises because the design or installation of many light fittings allows a significant fraction of the light produced to be emitted above the horizontal, so it goes up into the sky. This is the direct upward light. A much smaller proportion is light that is reflected upwards from roads, pavements and buildings. This is the indirect upward light.