Southampton City Council plan to fire giant lasers across the county which could ruin our view of the night sky – we hope it won’t but when you want dark skies firing a laser isn’t going to help.

An article has been published about this on ThisIsHampshire.Net.  Use your favourite search engine to find even more people concerned about the laser gateway.

Read about the laser gateway on the council website.  The laser gateway is due to be turned on to coincide with the 95th anniversary of the sinking of the Titanic. 

Now wasn’t this a genius idea from the Southampton Council.  A laser “gateway” spreading out in 4 directions for over 15 miles – and the really great thing about this laser lightshow is that according to the Southampton Council “spokeswoman” – there would be no light pollution.  Amazing!  See the comment from a spokeswoman for Southampton City Council below:

We conducted extensive consultations on the scheme. The designers assure us that lasers generate virtually no light pollution.

All that will be visible will be a pencil thin 2.7mm beam which will not affect star gazing in the way that street lighting or illumination from sports fixtures do.

The project, which is the brainchild of Southampton Partnership would see lasers shining from the Civic Centre clock tower which would be visible for up to 14 miles from the city centre.

So let’s spend about a microsecond analysing this statement shall we?  A pencil thin laser beam of 2.7mm I would also agree would cause no light pollution.  Also to someone with average eyesight it would be just about invisible from ground level, some 50 feet away from the beam – hardly the stuff that’s going to attract much attention. 

Of course the “spokeswoman” wouldn’t have realised that you couldn’t see a 2.7mm diameter beam at 50 feet – but then again, that’s not what we would have seen anyway.  As anyone who has worked with lasers knows, there will be considerable scattering off dust, particles and water vapour in the laser’s path all of which will blow the beam up to diameters much greater than 2.7mm – that’s what will allow you to see the beam from ground level, and from several miles away from the source.  Even if there were no scattering particles in the air at all – there is the natural divergence of the laser beam caused by diffraction from the output aperture, so even if the divergence is a milliradian or so, you will still get a beam diameter of 1 foot at 1,000 feet distance from the source.

It’s not bad enough the Council wants to create its own artistic form of light pollution, they also clearly have no understanding whatsoever about the physics involved either, this actually annoyed me far more than the potential light pollution.  Below is a comment I made to the Southampton Daily Echo.

In my opinion, the council’s plans amount to “vandalism” of the night sky.  There is a very good chance it will affect us. There will be light pollution with a great big searchlight across the sky.  I am very strongly against it.

 August 2007 – I am pleased to hear that this ridiculous idea has been dropped – for the moment at least.

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