Turn your lights down low
And pull your window curtain
Oh, let the moon come shining in
Into our life again.
- Bob Marley and The Wailers.
A few days ago, as we tried in vain to identify constellations, a friend suggested that we travel a few hours out of the city in search of adequately dark skies. It struck me as odd, since I already live a considerable distance out of the city, yet, even here, I was hard-pressed to find night skies dark enough to see anything but the full moon.
Today, an increase in light pollution means that millions of people across the world will never look up to see the Milky Way. For most of us urbanites, looking up at a night sky against which the galaxies stretch, swirling and pulsing in all their heavenly glory is a luxury, something reserved for holidays and camping trips.
Cities that never sleep
What colour is the night sky above you? If you live in or near a city, chances are it is the pink or yellow glow of artificial lighting diffused by smog. So brightly and continuously lit are our cities that it has become hard to find a single place with absolute darkness. When lighting is excessive and inappropriate, it can have negative consequences on human, animal and plant health.
This 24-hour oscillation of day and night is a carefully orchestrated dance as old as evolution itself. For billions of years, the predictable pattern of light and dark has defined the rhythms of life. It is embedded in the DNA of almost all living organisms and influences sleep-wake cycles, hormone release, eating habits and digestion, body temperature, and other important bodily functions in humans, plants, animals, fungi and microbes. For us humans, nights are a time for physical and mental rest and rejuvenation. In plants, the live-giving process of respiration occurs in the absence of light, when they consume oxygen, combine it with the food produced during photosynthesis and produce energy required for the plant to grow. The night also serves an important function for nocturnal species of wildlife who live a large part of their lives, hunting, foraging, breeding, migrating and hiding from predators under cover of darkness.
It's only in the last 100 years, since the birth of the industrial civilisation, that humans have radically altered this natural cycle by lighting up the night. And, as our cities inch towards forests, their blanket of eternal light banishes the darkness from these spaces, throwing entire ecosystems out of whack.
What is light pollution?
It is the brightening of the night sky by overpowered, poorly-aimed street lights, flood lights, billboards and other man-made sources which direct light above the horizontal and into the sky.
The International Dark Sky Association (IDA), a non-profit working to protect the night skies lists the following components of light pollution:
- Glare - excessive brightness that causes visual discomfort
- Skyglow - brightening of the night sky over inhabited areas
- Light trespass - light falling where it is not intended or needed
- Clutter - bright, confusing and excessive grouping of light sources.
Nothing natural about artificial lights
A recent study titled The New World Atlas of Artificial Night Sky Brightness estimates that 80% of the world's population lives under light-polluted skies and that the Milky Way is hidden from one- third of humanity. Dr Christopher Kyba, scientist at the GFZ German Research Centre for Geoscience measured the spread of light across the world using satellite images. He says, "Near cities, cloudy skies are now hundreds, or even thousands of times brighter than they were 200 years ago." The study concluded that most of the growth in lighting occurred in developing countries throughout South America, Africa, and Asia. And it's getting worse. The rise of LED lights in the name of energy efficiency has, Kyba found, increased the radiance and extent of artificial light coming from the Earth’s surface at night by 2 percent every year for the past four years.
(Use this interactive map to estimate the light pollution where you live).
But, the lack of complete darkness at night is not just bad news for star gazers. Skyglow, or the reflection of outdoor lighting in the sky, is a far more serious problem. As the need to illuminate spaces to make them safer and more accessible grows, night-time lighting increases. But, much of it is 'inefficient, overly bright, poorly targeted, improperly shielded and, in many cases, completely unnecessary,' the IDA says.
Constant exposure to artificial light can have negative impacts on human health and behaviour, and nocturnal ecology.
- It disrupts human metabolism and natural sleep-wake cycles, causing drowsiness, fatigue, even depression.
- The glare from streetlights and billboards creates distractive, hazardous driving conditions.
- Altering night into day can have devastating impacts on animals, birds and insects by disturbing their nocturnal activity, confusing predator-prey dynamics, hampering navigation and compromising their safety. In fact, scientists have found that light pollution along the Odisha coast is the second major cause of mortality among young Olive Ridley turtles.
- Excessive and inappropriate lighting can be a drain on energy resources.
Bring back the night
These tips might seem obvious but they can go a long way in reducing the stress from light pollution:
1. Turn off that switch: Start at home by switching off lights that are not in use. Outdoor lighting on the doorstep and driveway make night-time navigation easier and make us feel safer. But, use them only when necessary and remember to turn them off before you go to bed or if there is no activity around the house.
2. Use only as many indoor lights as you need: Keep your curtains drawn at night to keep light indoors. If you own a shop, restaurant or other business with a light up front, keep it off when the shop is closed.
3. Reduce the amount of decorative lighting: During festivals and other celebrations, it is common to see lights left on all light. Turn off all decorative lighting when not in use or opt for eco-friendly alternatives such as candles.
4. Dim your headlights: How many times have you been nearly blinded by the headlights of the car behind you? The glare from high-beam lighting is not just a strain to other drivers, but can be a major cause of accidents. Besides, they are only needed on poorly lit highways or country roads, not for city driving. If you have customised headlights that use HID, projector and halogen bulbs, go old school and paint the top half of your headlight black.
5. Shield outdoor lights: Choose outdoor light fixtures that shielding, meaning there is a solid cap above the bulb to keep light from shining directly towards the sky. You can also shield existing fixtures by buying appropriate shades that focus the light downwards and illuminate only that area of the ground where it is most needed.
If you find that the outdoor lighting around you, from say sodium vapour lamps, is disturbing, ask for it to be removed or replaced with more efficient, low-glare lighting that reduces the amount of light reflected into the sky.
6. Install motion-detectors on outdoor lights in commercial and public spaces: Instead of keeping lights on during the night for security reasons, installing motion sensors can reduce overall electricity costs while also cutting back on light pollution.
7. Warm it up: Warm lighting from yellow or amber light sources such as high and low-pressure sodium lights cause the least sky glow by far, as little as half or even quarter that of the best white light sources.
Watch Lost in Light, a short film on how light pollution affects the view of the night skies.
Featured Image: Mumbai - Night City (Flickr/ Vidur Malhotra; Public Domain)