Light pollution is stopping us from seeing the night sky properly

The cost of hiding the stars

We're a funny species. On one side, we like to lie on our backs by lakes in the woods, or at other dark places, and enjoy looking at a starry sky. Poets, artists and composers romanticize it. Astronomers look though this window at the rest of the universe.

But this contrasts with the results of a study just published that says light pollution continues to get worse, and in more and more of the world the stars are getting harder to see. Another side of this paradox is our work on obliterating our view of the stars is consuming an increasing amount of energy and lots of money.

It is easy to see this process happening. For example, we all agree decent street lighting improves safety and security. The objective of this lighting is to put light on the road and what is happening on it. The light that is not directed downward onto the road is wasted light, electricity and money.

If we stand on a hill overlooking a town, and can see the actual streetlights—as opposed to what their light is falling on—we are seeing wasted light. Light should be sent down towards the road not upward in our direction.

Looking down from a plane shows it better. From the International Space Station, the world shines like a beautiful jewel box because of the light being wasted by squirting it upwards.

Imagine we need to put a bit of light over our backyards, and install an unshaded light. Without a shade, half the light goes down onto the yard, and the other half goes upward, helping make the Earth look pretty for astronauts on the International Space Station. If we put a proper shade over the bulb, we can reflect the upward-going light downward, so that it does something useful.

Maybe a single, 100-watt bulb doesn't sound like much, but over a year the energy wastage and unnecessary cost add up. Now imagine millions, or billions, of people doing that. In addition, having a brilliant yard light spilling off your property into the eyes of the neighbours is a way to waste money while getting people upset at you.

Shopping centres and public places where customers and visitors park their cars need to be lit. In fact, lighting them probably costs a fair amount of money. A bit of planning beforehand, selecting appropriate shading and positioning of the lights can provide what is needed with a significant saving in energy.

Our local community administration has installed some very nice LED (light emitting diode) street lamps. They light the road and the bottom part of the cliff near the road very effectively. They spill so little light upwards that from above they are visible only as silhouettes against the pools of light below.

As we move into a world where we want to cut back and eventually cease our use of fossil fuels, and move on to other sources of energy, reducing wastage of energy will make the transition easier. It will also cut back the amount of carbon dioxide we are releasing into the atmosphere, while hardly affecting our way of life at all.

In professional astronomy, we can survey the world to find the places where the skies are darkest, clearest and steadiest. We can also put telescopes in space. However, there are far more amateur astronomers than professionals, and their ability to enjoy the sky is controlled by the environment they find themselves in.

“Dark sky” reserves are being set up across the country, where we can enjoy the dark, starlit sky, either with a telescope or binoculars, or just lying on a blanket, looking up. However, for those who have to enjoy the night sky from their backyard, just imagine how much they will thank you if you set up your yard light so its light stays on your property.


• Venus shines brightly, low in sky in the sunset glow, with Saturn, much fainter, nearby.

• Jupiter lies in the south-west, with Mars high in the south.

• The Moon will be full Feb. 5.

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.

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About the Author

Ken Tapping is an astronomer born in the U.K. He has been with the National Research Council since 1975 and moved to the Okanagan in 1990.  

He plays guitar with a couple of local jazz bands and has written weekly astronomy articles since 1992. 

Tapping has a doctorate from the University of Utrecht in The Netherlands.

[email protected]

The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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