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Ever wonder why can't we see the stars anymore?

A screengrab of current light-pollution In South Africa from Earth Observation Group, NOAA National Geophysical Data Center.

A screengrab of current light-pollution In South Africa from Earth Observation Group, NOAA National Geophysical Data Center.

Published Jul 23, 2021


On family trips to the Drakensberg, I recall gazing in wonder and awe at the shimmering night sky. It looked like a child had spilt a bottle of glitter on a dark tile floor, it was magnificent.

I thought that the Drakensburg was a special place because I could not see this many stars in the sky back home in the city, it was only much later I learned that it was light pollution that obscured our view of the heavens.

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Although Thomas Edison is widely credited with inventing the lightbulb, there were many who successfully produced some form of light-emitting device decades before Edison, but most could not make their inventions cost-effective enough for mass production until after 1850.

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English chemist Joseph Swan tackled the cost-effectiveness problem of previous inventors and by 1860 he had developed the light bulb that used carbonised paper filaments in place of ones made of platinum.

Swan's filaments were placed in a vacuum tube (lightbulbs) to minimize their exposure to oxygen, extending their lifespan. Unfortunately for Swan, the vacuum pumps of his day were not efficient as they are now making them impractical for everyday use. Edison realised that the problem with Swan's design was the filament.

A thin filament with high electrical resistance would make a lamp practical because it would require only a little current to make it glow. The day he successfully demonstrated his improved design of the lightbulb in December 1879, the future of the world was set to be a whole lot brighter. Maybe a little too bright.

Electric light is a beautiful thing, guiding us home when the sun goes down, keeping us safe and making our homes cosy and bright, but too much of a good thing proved to be quite damaging to ourselves and the environment. Artificial light from cities has created a permanent "skyglow" at night, obscuring our view of the stars.

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According to National Geographic “light pollution, the excessive or inappropriate use of outdoor artificial light is affecting human health, wildlife behaviour, and our ability to observe stars and other celestial objects.”

Light pollution occurs when light shines upward, downward, or is reflected upward, it is dispersed by layers in the atmosphere, which results in a glow that reduces the darkness of the night sky. Today, over 95% of stars that are usually seen with the naked eye are invisible.

There are four types of light pollution;

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Glare - Excessive brightness that causes visual discomfort such as bright electronic billboards and neon signs.

Skyglow - Brightening of the night sky over inhabited areas when light from buildings, vehicles and streetlights reflect particles and gasses in the atmosphere.

 Light Trespass - Light falling where it is not intended or needed such as street lights along country roads.

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 Clutter - Bright, confusing and excessive groupings of light sources such as shipping lights at ports and colourful, flashy lights at entertainment venues.

Excess light can disrupt our sleep patterns by suppressing our ability to produce melatonin which helps us fall asleep. This is the reason it is sometimes difficult to fall asleep after staring at a computer or television screen in the evening. Blue light from our cellphones is particularly disruptive to our internal clocks.

During the last decade, scientists have begun to discover that artificial lighting at night affects wildlife and ecosystems in numerous unexpected ways. Sea turtles get confused by the lighting from coastal cities and lose their ability to navigate in the ocean.

Migrating birds often get bewildered by tall buildings that are lit up and crash right into them. Some scientists even suspect that artificial lighting at night makes it harder for fireflies to find each other and mate. Several nocturnal species mistake man-made lights for moonlight while others are disoriented by them.

Stephen Maciejewski, a volunteer with the conservation non-profit Audubon Pennsylvania, patrols the sidewalks of downtown Philadelphia, the largest city in the US state of Pennsylvania. Maciejewski searches for birds laying on the pavement after crashing into one of many of the city’s towering skyscrapers.

He places the dead birds in a bag after noting important information and moves birds that are dazed or confused to a safer location until they regain their bearings.

On October 2, 2020, Maciejewski found 400 dead birds on his patrol, a far cry from the 20 or so birds he would normally find. The deaths were the result of a mass collision event, caused by a combination of overnight conditions which include a low cloudbank, fog and rain.

Normally, migratory birds would use celestial cues such as the stars to help them navigate. Disorientated by the cloud, fog and rain, they were drawn off course by the glistening lights of the city and smashed into the glass buildings. In total, an estimated 1 500 birds died that night.

Maciejewski’s pictures of the incident shocked the city of Philadelphia and the public called for action to be taken to prevent this from happening again. The “Lights Out Philly” initiative was announced in March 2021. This involved building owners, managers, residents and tenants agreeing to turn off or dim city lights between midnight and 06:00 during key migration periods.

Jason Weckstein, the associate curator of Ornithology at the Academy of Natural Sciences of Drexel University said that “it is not a national issue, it's not a state issue, it's not a city issue – this is a worldwide issue" More than 80% of the world lives under light-polluted skies, a figure that rises to over 99% for European and US populations.

Light pollution is growing at twice the rate of global population increase.

A November 2018 review published in Science outlined five key strategies to reduce lighting globally, which will not necessarily compromise its benefits. These are:

* The introduction of light to previously dark areas should be avoided.

* Lighting should be at the lowest usable intensity

* Lighting should only be used where it’s directly needed and shielded where possible.

* Lighting should only be used when required.

* Lighting should be “warmer”, meaning more orange colours should be used rather than in the harsh white spectrum.

As South Africans, we are quite fortunate to still live within an hour or two of the nearest pitch-black spots, perfect for stargazing or reconnecting with the universe.

You can still look at ways to make your home a little less bright by changing lightbulbs to those which emit warmer and softer light or just removing certain lights entirely. You’d be surprised at how little light your eyes need to see comfortably.

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