What Light Pollution Is, and Why It Matters

Light pollution and star gazing

Illustration: Gloria Hornby

What is your most treasured memory of the night sky? Mine is the time I emerged from a tent on my first night on a conservation project in the middle of the Kalahari desert in Botswana, two hundred miles from the nearest town, to see the extraordinary night sky of the southern hemisphere. The Milky Way was clearly visible to the naked eye, and millions of stars lit up the sky; I stood and stared at the universe displayed in all its splendour. All the familiar constellations were easy to identify, even for someone as untrained in stargazing as myself. Gazing up at the Kalahari sky definitely puts one’s own problems into perspective.

Sadly, this is not a sight I am used to, growing up and living in England, and it’s a rare one for most of us in the twenty-first century. The spread of light pollution, the phenomenon of the night sky being artificially brightened by street lighting and from other man-made sources, is common across the developed world, and increasingly it is only in these lonely nature reserves, far away from human habitation, that the night sky can be seen unblemished.

Global urbanisation, with the encroaching spread of twinkling office blocks and shimmering high rises, has taken its toll on the environment. Many species are nocturnal by nature, and artificial lights at night expose them to predators and reduce the time they have to find food, shelter and mates. This has had a detrimental impact on bird populations in particular. Nocturnal birds use the moon and stars for navigation during their bi-annual migrations, and in North America alone 100 million birds die each year due to collisions with night-lit towers.

Global urbanisation, with the encroaching spread of twinkling office blocks and shimmering high rises, has taken its toll on the environment.

Another tragic example is sea turtles, a species being driven to extinction by light pollution. The turtles, who have an imprinted orientation which propels them towards light, bury their eggs on beaches deep in the sand. On a natural dark beach, the horizon above the sea is slightly brighter than the horizon above land, so the hatchlings will instinctively take the shortest route down the beach to the water. However, on an artificially lit beach, they will be confused and will head towards the city lights and perish, never reaching the sea.

amazing sunset, evening sky, light pollution, beautiful sky

It’s not just rare species that are affected by electric light. Being exposed to constant artificial lighting can also have a profound effect on our own psyches too. In the words of astronomer Neil de Grasse Tyson, “When you look at the night sky, you realise how small we are within the cosmos… To deny yourself that state of mind, either willingly or unwittingly, is not to live to the full extent of what it is to be human.”

Ian Cheney portrays this very poignantly in his superb documentary The City Dark, filmed in 2012. So many of us will be familiar with the manic, 24/7 lifestyles driven by work and social commitments, where we neglect to form proper sleeping patterns and where our rhythms have nothing in common with those of the planet. In a world driven by bleeping smartphones and late nights spent in the office working to meet a deadline, our habits can be completely at variance with natural cycles. This disruption of what is known as the circadian clock (the 24 hour day/night cycle) has been shown to be linked with depression, insomnia, cardiovascular disease and cancer. This shouldn’t be surprising – when we do have the luxury of silence and darkness, this can bring about a sense of peace rarely found in the heart of a big city.

Looking at the bigger picture, what does light pollution say about mankind as a species? In the documentary, one comment stands out: “If our civilisation didn’t see the stars, didn’t see how big the universe was, would they come to the conclusion that they are much more important than this much tinier universe, because that’s all they see?”

None of us know what the long-term consequences of light pollution will be. Happily however, we are starting to become more aware of the scientifically documented negative effects, and this means we can take action.

If our civilisation didn’t see the stars, didn’t see how big the universe was, would they come to the conclusion that they are much more important than this much tinier universe, because that’s all they see?

One small step has already been taken: major cities around the world turn the lights off for one hour on the last Saturday of March to celebrate Earth Hour. Many offices and store-fronts currently leave the lights on overnight for advertising purposes or to prevent burglary. It has been estimated that the US economy loses between around 2 billion dollars a year as a result of this wasted electric light. If all employees campaigned for their places of work to turn off their lights at night, and the law was changed so that those businesses that persist in leaving the lights on were taxed more severely, this could have huge benefits for the environment and for those nocturnal species with which we share our planet.

light pollution, stargazing, festival of lights

Another positive step we can take is to ask local councillors to change street lamps to directional, low energy lamps, and start buying LED light bulbs to use in our own homes. On a more ambitious scale, lighting designer Herve Descottes, who designed the lighting for New York’s Highline Park, is looking at how we can design our cities in a way that reduces both energy and environmental costs. He has adopted a new system of lighting using dark sky-friendly lighting fixtures that direct light down, rather than up. The lighting comes from a hidden source in the ground, eliminating the glare. If other cities around the world were to start adopting this design for street lighting, urban skylines could look very different.

And what about us? If you’re reading this article on your iPad in the middle of London, Manhattan or Hong Kong, you might be feeling a little depressed. How are we supposed to reconnect with nature and the night sky while we juggle work and social commitments in the middle of an enormous, brightly lit city?

Aside from campaigning for change in our workplaces and with our local authorities, there are small and easy steps we can take to reconnect with our night skies – and you don’t have to travel to the African wilderness to see the Milky Way. Stargazing tips are a click away and anyone, even big city dwellers, can become an amateur astronomer. Even with a normal pair of binoculars you should be able to make out the main constellations on a clear night – just find a park, or go to the top of a tall building, and study the night sky.

You may be surprised at how much you see when you start to look.


Author: Emily Watson

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