Somewhere in South London on a bright and almost absolutely clear spring day the evening begins to slowly encroach. As the sun dips beneath the horizon and the once intense blue sky fades darker and darker towards black, something is missing; something is not quite right. What’s not there is hard to gauge. For as far as most of us urban or semi-urban dwellers can recall, the sky is and always has been just the way it is on this particular night. Sure, there are a few white dots here and there, some of them a bit brighter than others. Perhaps even depending on the time of the year or the weather conditions, a handful more are seen on this particular night than are usually visible.
But where is the spectacular performance of the night sky that has captivated humans for thousands of years? Where is the cloudy and ethereal Milky Way that is supposed to stretch above our gaze, igniting our imagination and sense of wonder? What happens when we lose our connection to something greater than us?
The reality is that the night sky that we’ve evolved under, that we’ve gazed in wonder at for thousands of years, and that we’ve always known, is still there. It’s just gotten much dimmer. Much like an old speaker, whose once vibrant and intense tones faded through the years until only barely audible, the urban night sky has been turned down to a point of near mute.
A Brighter World
All across the world, urban areas are getting brighter every year through a combination of poorly designed lighting fixtures, increased brightness levels, and urban sprawl. The result is a night sky that has faded from a window to a once unimaginably rich and complex expanse, to a soft glow of yellow and black, where we struggle to distinguish between stars, satellites, and planes. As a result of light pollution, more than two-thirds of North Americans and Europeans born today will never experience a sky dark enough to see the Milky Way. This signifies an ultimate disconnection from nature, a poetic loss and a diminution of a great awe.
In the grand scheme of human life, light pollution is a rather recent problem. Looking back, one can find the earliest mentions of it in popular astronomical literature. In 1866 the French science author Amédée Guillemein wrote that the dimmest nighttime skies were located in “great centres of population, by the illumination of the houses and the streets.” But at this time, the dimming night sky was caused by something other than simply poorly lighting fixtures. After all, Guillemein wrote of the illumination of urban areas thirteen years prior to Thomas Edison’s incandescent bulb. A considerable amount of the light pollution was caused by what we today consider air pollution. Cities such as London and Paris were being slowly suffocated through street dust and excessive wood and coal smoke.
A Western Problem
Following World War II, the problem quickly worsened as lighting fixtures became cheaper and more accessible, and cities throughout North America and Western Europe began to sprawl outwards. As air pollution decreased and became more regulated, light pollution went unchecked. Observatories moved out of urban centres, citing a lack of proper viewing conditions and generations born in rapidly developing urban areas grew with no reference to the once bright heavens above. A furthering dependence on the car brought lights to once darkened rural areas to light a way for the occasional car while stringing together ever expanding, ever brightening clusters of urban light.
Overly bright, poorly targeted and often unnecessary lighting across commercial properties, offices, factories, streetlights, and illuminated sporting venues amounts to light pollution with drastic effects. It disrupts nocturnal ecology, altering breeding rituals, reproduction and reducing populations, in particular among amphibians and endangered species such as turtles. Humans, too, experience disruption to circadian rhythms through the suppression of melatonin — a hormone critical to proper sleep, a healthy immune system, balanced cholesterol, and the functioning of key glands. But light pollution is not an inevitable problem that simply happens as the world becomes more urbanised. Light pollution is a problem that can not only be slowed, but also reversed with a combination of communication, awareness, and better design decisions.
Remembering the night
One of the greatest challenges currently faced is not merely how to solve light pollution, but rather, why should we? Two-thirds of North Americans and Europeans born today will never experience a sky dark enough to see the Milky Way. Communicating the possibilities of a better night sky poses a significant challenge: how can we convince people care about something they’ve never seen?
2015 was the International Year of Light. However, just because it has passed, doesn’t mean we should stop caring. For everyday citizens, the first step in improving their skies is to demand better urban lighting from local authorities. Preferably ones approved by the International Dark Sky Association, as these lights have been designed to decrease their impact on the night sky. These lights are at the simplest, shielded from above, directing light to where it needs to go and not into the sky.
Designing for Darkness
There are a number of other ways of improving the design of outdoor lights. Fixtures should not shine light above 15º below the horizon, and preferably the target area should be determined via adjustable side shield. Furthermore, the light should only hit the area that is needed. While that point seems obvious, pay close attention to urban lights. How many of them point upwards into the sky, shine unwanted lights into unwelcoming windows, or create glare in our eyes?
Proper outdoor lights should only be on when needed. This is a problem easily solved through the integration of cheap sensors that read light levels to determine when the light is actually needed, or furthermore, how much light is needed; a much improved method to simply switching on at a set time of the day.
The luminaire itself should not be brighter than necessary. Over the past sixty years outdoor public lighting has been getting brighter and brighter in many municipalities, owing to the belief that brighter equates safer. The reality is that when lighting at night is too bright, it causes us to only see what is lit, thereby reducing our eyes’ ability to render objects in the dark.
Lastly, the light should minimise blue light emissions as much as possible. Numerous research studies demonstrate that blue light penetrates further into the eye and can cause damage to the retina. Additionally, some wavelengths of blue light affect our body’s ability to produce melatonin, leading to disrupt the body’s circadian rhythm.
As the sun falls, and the night sky appears again, look up and see what you can discover. If you’re in an urban or semi-urban area, chances are the discoveries you can see are hidden away by bright lights not in the sky, but on the ground. Pay close attention to the street lights you pass and ask yourself, ‘what are they lighting?’ Are they succeeding in hitting their targets, or are they also spilling excess light into the night sky? Once you’ve noticed a bad light, you can’t stop noticing them. They’re everywhere — but perhaps with a bit of communication, a push for awareness, and optimism that soon we’ll begin to slowly remediate our night sky — the night sky can be reclaimed.