The 365 Ways Blog

Michael Norton is author of "365 Ways to Change the World", which provides an issue for each day of the year, interesting facts, inspiring case studies of people doing things to address the issue and ideas for action. Originally published in the UK, versions with local content have been published in Australia, Canada, India, South Africa and the USA. To find out more visit our website:

19 August 2007

Fight light pollution

Once upon a time, you could look up at the sky and see the stars. Today there is ligt pollution almost everywhere. This is when there is so much ambient light being emitted from our cities, towns and roads that the stars become far less visible than they were in Galileo’s day.

"Excessive poorly designed outdoor lighting wastes electricity, imperils human health and safety, disturbs natural habitats, and increasingly deprives many of us of a direct relationship with the night-time sky which throughout human history has been a powerful source of reflection, inspiration, discovery and plain old jaw-dropping wonder.” – David Owen writing in the New Yorker, 20.8.07

If you really want to explore the stars, you might now need to go to the middle of the Kalahari or Gobi deserts or climb to the top of Mount Everest to avoid the problems of light pollution.

The International Dark-Sky Association (IDA) aims to highlight this problem and mobilise people and communities to do something about it – which they can do by pressing for sky-friendly standards for outdoor lighting and the establishment of dark-sky parks and preserves.

Here are two things that can you do about this problem:

1. Understand that there is a problem. This is a good starting point. There is an exercise that you can do on the IDA website, which involves rating photographs. See below.

2. Join the IDA; there are Chapters in some countries of the world, but not in many others. If there is no Chapter in your own country, why not start one.

Rating light pollution
You are invited to review a series of photographs which depict various lighting fixtures either in isolation, or installed. You then rate each on a scale of 1 to 10 where 1 is poor and 10 is excellent. Your rating may be a general assessment or an appraisal which takes into account these five essential elements of outdoor lighting:

Glare: Intense light that contrasts excessively with shadowed areas, so reducing overall visibility. Glare may be annoying or discomforting.

Light trespass: Artificial light that spills from one property onto another. Look at how much light shines onto other properties, including structures or vegetation?

Energy waste: Think about if the lighting is excessive, whether it meets the task it was installed for well and in an efficient manner, whether the area is overlit, and whether there is too much contrast for good visibility.

Impact on night sky: Light that shines directly up into the sky and reflected light from installations that are too brightly lit create sky glow

Visibility: This is the capacity of something to be seen under present lighting and weather conditions and the reason for most night lighting. Think about whether the lighting helps or hurts visibility.

Like all surveys, this survey is subjective. You can add your comments with you rating especially where you rate a particular example particularly highly or poorly. Go to

International Dark-Sky Association: