I have recently undertaken a detailed survey of light pollution in south Gloucestershire, including a region around the A417. This was commissioned by the Cotswold Conservation Board in Northleach and funded by the Highways Agency. Highways wanted to know the current state of light pollution within 20km of the A417 with a view to minimizing the impact of the proposed changes to that road. Prior to Covid, I had been on a committee with the Conservation Board in an effort to get some form of Dark Sky Status for parts of the Area of Outstanding Natural Beauty (AONB) of the Cotswolds. I was one of two astronomers asked to sit on the committee, the other being from the Chipping Norton Astronomical Group.
As amateur astronomers we are very much aware that dark skies are needed for many of our night time observations and that light pollution seriously impacts our ability to see and image fainter objects. It is only when viewing the Moon and planets that light pollution is not a major problem, but for all other objects the ever-increasing glare in our night skies is a great nuisance to us.
It is estimated that the extent of light pollution has increased by around 10% each year, thereby doubling within 8 years. Apart from the negative impacts on both amateur and professional astronomy, light pollution has many other detrimental effects.
The switch to LED lighting has not reduced light pollution, quite the opposite. Moreover, it has increased the amount of light in the blue part of the spectrum, which is even more damaging to wildlife. Light pollution seriously affects the predator/prey relationship for nocturnal creatures. The extra light gives an undue advantage to the predator, such as bats, owls and foxes. This then leads to a crash in prey numbers, with a knock-on effect on the predator. Prey that does survive may move to darker places and thus there is loss of habitat for the prey. The impact on insect populations has been dramatic and, remember, we depend upon insects for the entire food chain.
Evolution is a slow process, and none of us, insects, animals or humans evolved to live in permanent light. It affects all our circadian rhythms, disrupts sleep patterns, and leads to additional stress.
It is not often realised how far reaching light pollution can be. Many of us will have seen badly directed security lamps, those wretched 500W things, that dazzle us when we merely pass nearby on the road. These are completely unnecessary on a typical house and can be a major nuisance to those around. They are often badly directed and are frequently tripped by a passing cat or fox, and stay on for a while. The tripping does not alert neighbours to think anything untoward is happening, as it happens so frequently, and so they are ignored. Even if you did look to see what was happening, you would be unlikely to see any detail against the dazzling light. As a security tool on a house, they are worse than useless as they are costly to run, annoy the neighbours, and cause serious light pollution. One some distance from my house has often disrupted astrophotography in my back garden.
Lights from towns can spread a long way from the town itself, as my research clearly showed.
Below is a fisheye lens view of the sky near Daglingworth about 5 km from Cirencester
Notice how far up from the horizon the glow has spread. This was one of the darker sites for which I took readings. Even Stroud, at 13km distant is still producing some sky glow, while the glow from Stratton and Cirencester almost a third the way to zenith.
The photo below is of Rendcomb, which lies some 8km north of Cirencester.
The photo was taken above the village on a lane near to the White Way. Although it is clear that Rendcomb was below me in altitude, the lights from the College’s Astroturf, more than 1 km away, are dazzling, despite using the trees to block the direct glare. It is clear that these lights are poorly directed, as they are clearly pointing upwards at some angle! The light pollution is dreadful. Moreover, this was after 8.30 pm and the pitch was not in use. I could clearly read all the camera settings from the lights of Rendcomb. This emphasises how far-reaching light pollution can be.
One last photo here emphasises the impact of major towns and roads:
This is taken from Crickley Hill Country Park that allowed me in after sunset. The lights of Gloucester are to the left, with the A417 coming out towards you. The M5 crosses in front of Chosen Hill and Cheltenham to the right. Note that the lights of moving traffic are more separated and therefore cause less light pollution. See if you can spot the Plough in the sky above and to the left of Cheltenham.
So, what can we do? Well, we need to be more aware of any unnecessary light pollution we cause ourselves. Do we need that outside light on all the time, that security light or the curtains left open? Check that any external lighting is directed downwards and not outwards.
The Highways Agency are doing their bit, as they have decreed that the new section of the A417 will not be lit. I have supported this decision. After all, the section it joins is currently not lit either. Despite the local council requesting lighting, I am pleased that Highways are holding out on energy and environmental grounds.
We can campaign for street lighting to be reduced, or at least dimmed, with future lighting and bulbs to be better directed and using less white LEDs, but more environmentally sympathetic colour temperatures. Less lighting does not mean less security. There is growing evidence that crime rates actually fall when lighting is reduced. Criminals want to be able to see what they’re doing!
If we do not take action soon, we will lose the night skies, reduce wildlife and impact our own health. Unlike other types of pollution, light pollution is reversible, could save energy and let many more people enjoy the wonders of truly dark skies.
As a society we need to see what action we can take to prevent the loss of dark skies. Perhaps some of you feel strongly enough to form a small focus group that could recommend a way forward. Please email your Coordinator Neil at firstname.lastname@example.org if you could take part.
Furthermore, in the meantime, we could all get behind a petition to Parliament to pass a Dark Sky Law. If enough people sign it, Government will have to give it consideration.
Details can be found at https://petition.parliament.uk/petitions/632558
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