Light pollution is the glow visible across the night sky from the reflected light of streetlamps and other forms of artificial illumination.
A truly dark sky is breathtaking, but the sad reality is that few of us have easy access to such skies, and astronomers have long been advocating for darker skies and for a reduction in light pollution.
Other voices have recently been added to ours, with environmentalists, ecologists and healthcare professionals recognising the importance of a natural day–night cycle that includes darkness.
Around the British Isles, protected Dark Sky Parks are springing up in places where great efforts have been made to combat skyglow.
But while these sanctuaries of darkness are valuable and important, they are not always convenient places to visit.
So what can be done in our local streets and parks to help reduce light pollution? Are there practical steps we can take to make our local skies darker?
Luckily, excessively bright light at night is covered as a statutory nuisance in the same way as noise.
Under the Clean Neighbourhoods and Environment Act 2005, any artificial light may be reported if it is considered “prejudicial to health or a nuisance”.
Knowing you have the law on your side is important, but this should be a last resort only if you’ve explored all other avenues.
Arm yourself with info
First and foremost, it’s about education.
Educate yourself in the various forms of light pollution and then spread the word in your community about the benefits of dark skies.
Start with your local amateur astronomy society, and work to identify the places in and around your community that are best for stargazing.
Keep an eye open for developments that might threaten those darker sites
It’s easier to raise awareness of good street lighting at the planning stage than it is to seek improvements after bad lighting has been installed.
Learn to muster your arguments, and make sure you have evidence to back them up.
If you attend public consultations and present this information clearly to developers, you might be surprised how receptive they are.
The British Astronomical Association’s Commission for Dark Skies has a fantastic online resource of evidence to back up your assertions.
Another great way to get the message across is to work with your local community council and amateur astronomy society to put on public stargazing events.
Such events help bring your community together, and they are platforms where you can raise the issues of local light pollution.
Most people are oblivious to bad lighting, and a little gentle education can go a long way.
Larger stargazing events may even have a demonstrable economic benefit to your community.
Galloway Forest and Northumberland National Park – both protected Dark Sky Parks – have shown that astronomy tourism is an important economic driver in rural areas, and their local councils have adopted lighting policy that further protects their valuable dark sky asset.
While local examples of poor lighting can be addressed to the individuals or businesses responsible, skyglow is best tackled at the council level.
Councils are legally obliged to consult on their local development plans; in conversation with council planners and lighting engineers you should stress the need for less wasteful lights that have zero ‘upward’ light.
Developers or planners may not listen to astronomers complaining about vanishing stars, but they will pay attention when you explain that night-sky-friendly lighting is cheaper, produces less carbon dioxide, is better for wildlife and for human health, and is safer.
Cite examples of councils that have already addressed skyglow by installing night-sky-friendly streetlights.
Dumfries and Galloway Council and Northumberland County Council have both undertaken a refit of all of their old, unshielded streetlights and replaced them with zero upward light LEDs.
It’s no coincidence that these councils are near two of the UK’s Dark Sky Parks, and while the initial impetus might have come from astronomers promoting off-season tourism, the reality of lower energy bills and carbon emissions made these refits even more appealing to council planners.
When struggling to find somewhere to stargaze that’s free from glare or skyglow, it can often feel like we’re fighting a losing battle against light pollution.
But with public interest in astronomy skyrocketing thanks to recent eclipses and space missions, plus programmes like the BBC’s Stargazing Live, and with councils looking for ways to spend their money more efficiently, the tide might be finally turning.
Three types of light pollution
Familiar to all urban stargazers, this is the glow from streetlights reflected back down to Earth, drowning out light from fainter stars.
This could be a streetlight shining into your bedroom or a neighbour’s security light coming on: light from any source that shines where it’s not wanted.
Bright light sources can spoil your night vision – annoying for stargazers, but also dangerous, as it can dazzle drivers and cause accidents.
Steve Owens is a dark skies campaigner, On Tour Manager at Glasgow Science Centre and author of Stargazing for Dummies