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Light Bright: Night Sky Obscured By Artificial Light

Have you ever seen the Milky Way? Like really seen it?

(Photo via Shutterstock)

There’s a good chance the Milky Way is a lot more impressive than you think, because many people’s view of the night sky is obscured by lights illuminating the night. About one-third of all humans on Earth cannot see the Milky Way at night. In North America, that figure is worse, with about 80% of people unable to view the galaxy.

It’s not just streetlights blotting our view of the night. In cities and towns all over, office buildings and factories glow at all hours of the day and night, plus our houses are illuminated and the headlights of our vehicles cut into the dark. Even billboards and signage advertising restaurants and stores contribute to the problem.

And the bigger the metropolitan area, the more obscured the view. You can see for yourself using the World Atlas of Night Sky Brightness.

All this artificial light illuminating the night is a form of pollution. Just like other kinds of pollution, light pollution — the brightening of the night sky by light — is human caused. And just as with other kinds of pollution, the effects are far reaching. Light pollution impacts our wildlife and ecosystems, our own health and even something as simple as being able to gaze at the night sky.


Words to know

Circadian rhythm: Natural processes that follow a 24-hour cycle. These natural processes respond primarily to light and dark and affect most living things.

Illuminating: To supply with light.

Industrialization: The development of manufacturing using machines.

Melatonin: A hormone that helps control the body's sleep cycle.

Milky Way: The galaxy that includes the solar system.


Light pollution may not seem as serious a threat as chemical spills or even litter, but it is among the most chronic environmental disruptions on the planet. And it keeps getting worse. Research conducted between 2012 and 2016 found that light pollution increased by 2.2% a year.

For animals, artificial nighttime light can have devastating effects because it affects their migratory patterns, sleep cycles and even habitat formation. Countless insects are killed because they are attracted to artificial lights. And many birds and even sea turtles die because artificial light causes them to lose their way while migrating.

Even humans can be out of whack because artificial night light can interrupt our sleep cycles and effect our circadian rhythm. Among the many processes regulated by the circadian rhythm is the production of melatonin, a hormone that plays a role in sleep. Increased light at night, when it should be dark, slows melatonin production, which can cause anxiety, fatigue, headaches and sleep deprivation. Studies have also shown a link between reduced melatonin levels and cancer.

Light pollution is the byproduct of industrialization. Since the invention of the light bulb in 1879, our nights have gotten brighter and brighter. The benefit of the illuminating glow that surrounds our metropolitan areas is that our society has become safer and more efficient.

However, much of the light we see at night is inefficient, too bright, not targeted to the right locations or just not necessary. Think of your own house. Do you ever have lights on in rooms you aren't in? That contributes to light pollution. And have you ever driven by an office building almost fully lit at night and wondered why all the lights were on? This a major contributor to light pollution in urban areas.

Contrary to popular belief, our efforts to save energy and money by using LED, or light-emitting diode, bulbs, is making light pollution worse, not better. This is because while LED lights are more energy-efficient, the unintended consequence of the switch to LED streetlights has been the creation of more light, which means more light pollution.

The blue light emitted by LEDs, as well as our phones and other computerized devices, is linked to reduced melatonin production in humans. Similarly, the blue and white light created by LEDs has more negative effects on wildlife than other forms of light.

Is there hope for a darker future — at night anyway? Yes, but as with other forms of pollution, progress will require large-scale efforts. You can do your part by encouraging your local governments to adopt lighting ordinances that address light pollution and advocate for responsible use of artificial light.

You can also ask your parents to think about the lighting around your own house. Is your family using low-temperature, energy-efficient light bulbs? If not, ask your parents to think about switching. And think about installing dimmer switches, motion sensors and timers and use fixtures that shield light to reduce glare.

And the easiest step of all to do your part to limit light pollution: Simply turn off the lights to rooms you aren't in.


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18 nov 2021


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