Beauty and waste

Ken Tapping, January 9, 2013

In the sky this week…

  • Mars lies low in the southwest after dark.
  • Jupiter dominates the southern sky during the night. Saturn rises about 3 am.
  • The Moon will be New on the 11th.

One of my Christmas gifts was a book of photographs taken of the Earth from space. These pictures were taken while it was night on that part of the Earth, and show the works of our civilization from space. Cities are jewel boxes of lights, connected by shining threads – the highways.  In some images the Earth is crowned with green displays of the aurora.

At the most superficial level, these pictures are just stunningly beautiful. When one looks a little deeper they are very saddening, but then at the next level down they indicate a great opportunity to do something towards ameliorating one of the most serious problems facing us today without significantly impacting ourselves at all.

The light that reached the International Space Station and was recorded in those pictures was utterly wasted light. Instead of being directed at what was to be illuminated, it was just squirted upwards into space. Rough estimates suggest that at least a quarter of the light we generate outside our homes to light our streets, sports fields, parking lots and backyards ends up lighting up the sky or just irritating the neighbours. In these days of pressure to save increasingly expensive energy, why waste energy that is easily saved without impacting us at all?

For example, an unshaded bulb used to illuminate the back yard shines in all directions. About half of its output goes upwards and is wasted. If you install a reflective shade above the bulb, that wasted light will now be directed down into the yard. If the original bulb was 100W, you could find your yard is now as well-lit using a 60W bulb. You’ve just reduced the cost of running that light by 40%. You can buy outdoor fixtures with built in reflectors, which helps put the light where you want it.  However, set it up so that it illuminates your yard, not the one next door. A useful guiding principle for backyards, parking lots, sports fields and any other exterior lighting, is that anything radiated above the horizontal is wasted. You can avoid this by using appropriate shading and taking care in positioning the fixtures. Now you can use lower power bulbs.

We live in a world increasingly concerned about the impact upon the climate of the greenhouse gases we release into the atmosphere. Similarly we are worried about the effect of reducing those emissions on our way of life, or the consequences of our not reducing them. Here at least is something that we can do towards addressing the problem while not degrading our way of life. It will also reduce energy consumption and save money. Modern, efficient lighting technologies such as light-emitting diodes will offer the opportunity to use your expensive electricity even more efficiently.

Another benefit of intelligent lighting is darker skies. Light illuminating clouds and haze in the atmosphere makes the sky glow. Reducing that sky glow will show the skies our grandparents and great grandparents enjoyed. Have you ever seen the Milky Way from your backyard? You might want to consider spending some of the money you save on a telescope.

Ken Tapping is an astronomer with the National Research Council's Dominion Radio Astrophysical Observatory, Penticton,  BC, V2A 6J9.

Telephone: 250-497-2300
Fax: 250-497-2355
E-mailken.tapping@nrc-cnrc.gc.ca

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