Many visitors to the area of Wadhurst comment on our dark sky which has an average darkness of 20.08 with the best area measured at 21.09. This is a very good reading for a village in the Southeast of England. However, we felt we could not afford to sit back and hope it stays that way or could not be improved.

The survey document was created in response to an invitation by the Wadhurst Parish Council who wished to take suggestions for any ways in which the Parish Council could help the various groups and societies of the parish. Our request was that the council adopts a “Dark Sky Policy” for street lighting. We also volunteered to perform a “Dark Sky Survey” in order to set a baseline so that the sky quality of Wadhurst can be recorded and monitored over time.

We were lucky in that Wadhurst only has 163 streetlights, the majority of these are concentrated in the more populated areas. However, there were 16 different types of street light fitting, some good, some dire.

The sky readings were taken at 10 carefully chosen points around the parish with a Unihedron SQM. The readings were taken away from direct light contamination from adjacent street lights. In this way the light pollution of the sky was measured rather than the actual lights. The readings were always taken at the zenith at each location over several months when there was cloud or clear sky but never fog, mist or rain or when the Moon was above the horizon as this would contaminate the readings. Taking readings of sky darkness when it is cloudy may seem odd but it is at these times that light pollution is reflected by the clouds and is a good indication of the level of pollution. It became evident that sky transparency as well as cloud altitude and density also had an effect on the readings as well as humidity. However, although the readings in any particular place varied from night to night it was possible to see that certain areas were better than others and so it was decided that the best way to correlate the data to make it meaningful was to average each set of readings taken at a particular location. In that way all the variables were made irrelevant. It was also decided to create a whole parish baseline by taking all the averages from all the locations and averaging them, in this way you could immediately see what areas were worse than the average and make them a priority. The data eventually comprised hundreds of individual readings.

Copyright was a big concern in creating the document. Do not assume that any image on Google or the internet is there for the taking. 80% of all images are copyright and there are some unscrupulous types out there that make a lot of money out of copyright scams. There are but two images in my document that are copyright. Permission to use the excellent image on the front cover by Don Goldman of Astrodon Imaging was given providing I gave him credit. The second image is on page 6 copyright S.Barnes, was taken from Wikipedia and the copyright status was indicated and all that was needed was to give S.Barnes credit for the picture. All other images, graphics, maps and photos etc., were of my own making. If you want any please let me know and I will send them to you.

Finally, Parish Councillors are usually well meaning but may not be experts in their areas of responsibility. A clear easy to understand explanation is needed or they may well switch off. Councils now have to comply with the National Planning Policy Framework 2012 (NPPF 2012) details of this are on the last page of the document. Adopting a dark sky policy may help the Parish Councillors to tick the box to comply with NPPF. Financial concerns and benefits are also addressed in the document. Enough from me, if you need to contact me use Best of luck…Phil Berry

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By Wadhurst and District Astronomers

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