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Posted by Graham Relf at 18:00 on 2010 May 05
I read recently with some concern that my local council, North Tyneside, is now doing trials of white LED street lighting. I applaud the idea of using more energy-efficient lighting, as long as the energy cost of replacing all the lamp posts does not exceed the savings for years to come.But why must the light be WHITE? The spectrum of an LED can be tailored considerably by suitable use of materials. I doubt the emission could have such a narrow band as the old sodium lamps but surely we should campaign for as narrow a band as possible. Then we have a chance of masking it out with corresponding filters. Would the public complain if the lights were some shade of yellow? I can think of no good reason why they should. We need suppliers and councils to agree on the colour band though, so it is the same everywhere.Quickly, before it is too late!
Posted by David Arditti at 02:46 on 2010 May 06
The answer is that the colour of sodium light is highly unpopular with the public. When consulted, people (non-astronomers) always demand white streetlights. They say it makes them feel more secure. This is behind the push towards white LEDs, as well as energy saving, and it is a highly political issue. I think it is very unlikely that astronomers will be able to bring pressure for non-white new lights to be introduced. Even Bob Mizon, when I asked him about it, expressed the belief that we cannot avert a move to white streetlights in towns, and the focus of the CfDS has been on getting the beam-pattern of lights improved rather than on their colour. Unfortunately, the greater upward reflectivity of white light off grass etc. is likely to more than compensate for improvements in beam patterns in terms of contribution to skyglow in the future.All round it is very bad prospect for astronomy and I often stress it at meetings as I don’t think amateurs realise what is coming. Here on the edge of London, where many of the lights in the centre of the city have already been changed to white, I can see the effect very clearly. If we could harness the support of the professional astronomical community more I think we would stand more chance of making an impact, but I think the trouble is, as they don’t generally observe from the UK, they don’t see it as such a big issue. They should all regard it, however, as part of their job to be working to preserve the sky that will inspire the next generation of both professional and amateur astronomers.
Posted by Duncan Bryson at 19:40 on 2010 May 06
Dear AllThis Might Not Be A Long Term Solution For Astronomers Because "LED’s" Produce A Brighter Light (LED’s Are Usually Brighter Anyway) But What You Could Do Is Ask Them About Turning Off The Lights After 1am For Instance (Bob Mizon Has Suggested This In The CfDS Newsletter)Duncan
Posted by Kim Burton at 20:11 on 2010 May 07
As LEDs don’t need to warm up, why can’t they use motion sensors. The lights could just come on when needed and save power.
Posted by Duncan Bryson at 09:41 on 2010 May 09
That Sounds GoodAs Long As You Don’t Dance Around Because You’ve Seen A New Planet Or Something (And Activate The Sensor On The Street Light) That Would Be A Good Idea – As Long As The Council Have Enough Money To Fund ItDuncan
Posted by Dale Holt at 13:29 on 2010 May 10
Thanks to David for outlining some of the lesser known facts around LED street lighting. It does sound very worrying and already happening if David can witness deterioration from his NW London location.I have often wondered why more of the low level bollard type lighting isn’t used by local authorities as the units must be considerably cheaper that full lamp posts, especially for pedestrian only applications.Movement detection is also a good idea but with the energy usage being that much lower with LED’s the cost & environment cards will have already been satisfied to a greater extent, the advantages to residents & councils will not be so attractive.I think the serious option for many astronomers trapped in light polluted areas will be to concentrate or areas of astronomy that are less effected by the scourge of poor lighting, i.e. Lunar, Solar, Planetary. Double stars etc or to join the increasing number of UK astronomers accessing scope remotely under really dark skies. I appreciate that theses means imaging and not visual observation but what else can a small group of astronomers realistically do to prevent it?Dale Holt
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