How Many Starts Did You Count?

How Many Stars Did You Count?

stars in orion As part of our Light Pollution campaign (first launched in 2003), CPRE teamed up with The Campaign for Dark Skies (CfDS) to encourage individuals to do a start count from their location. Participants were invited to counts the stars within the rectangle of the constellation Orion's 'shoulders' and 'feet' for one night in the week of 20-24 Dec or of 14-21 January. In fact, such a wide window was needed because of the cloudy skies on most nights in the South of England. How many did you count?*

But when the skies are clear what would you rather see - extra-terrestial stars or the intrusive glow of city lights, street lights and floodlights? Maps of light pollution (see below or this link for an explanatory PDF version) for the South of England show a significant increase from 1993 to 2000. There are fewer and fewer places in the countryside where you can enjoy dark, starry nights. But the issues go further than that. There are concerns about health, the environmental cost, the impact on wildlife and the economic cost (estimated by CfDS as over £8 million for January for street lights alone). CPRE's national website outlines the nature of the problem but also offers solutions.


Light Map 1993		Light Map 2000

Light Pollution is Avoidable

light spillage Better designed street and road lights, security lights that come on only when needed, and light sources that beam downwards (and not spill light sideways and upwards as in the example shown here) are some of the solutions. Hampshire County Council is one local authority that is taking a lead by introducing highly reflective road bollards to replace the more traditional illuminated versions. They have updated street lighting so lanterns use shielding to avoid light spilling onto adjacent properties.

Today there is no excuse for poorly implemented lighting. Last year (April 2006) exterior lighting joined noise and smells on the list of things that can be treated as a Statutory Nuisance under the Clean Neighbourhoods and Environment Act 2005 (see DEFRA Guidance).

You too can play a part

Make sure that your own outdoor lights are not wasteful
Identify sites where light pollution is unreasonable
Make representations to your local council
Ask retailers to promote more environment-friendly lighting
Take advantage of the new legislation to encourage enforcement.

For more information on what CPRE is doing and what you can do and how to do it, read CPRE's Light Pollution Action Plan, available at the Light Pollution campaign pages at the CPRE national website.

* The author counted 8 initially, but then 24 after allowing 15 minutes for his eyes to acclimatize. That's stars down to about magnitude 5 (1=brightest). In really dark skies, stars with magnitude 6.5 and above are just visible to the naked eye. Orion has around 66 of these within the viewing rectangle. In heavily lit urban neighbourhoods, the cut off point is around magnitude 3, that's four stars within the defined rectangle (including the three stars of Orion's belt). There are a further three stars between magnitudes 3 and 4. There is a slide show at the CfDS website showing how many you can see at different magnitudes.

February 2007