Monday, June 18, 2007

Hooray for dark skies

My earlier post on dark-sky communities for amateur astronomers has spawned a long discussion of light pollution at Bad Astronomy. I'm cross-posting my contribution here:

Kudos to everyone who noted that dark-sky retirement communities are a neat fringe movement, but that it’s more important to reduce light pollution where average people live.

I recently flew back from Tucson, AZ where I had an observing run @ Kitt Peak National Observatory. Tucson’s population is half a mil, but you wouldn’t know it standing on Kitt Peak, only 55 miles away, where I enjoyed dark skies, the summer Milky Way, and two nights of data-taking scientific happiness. How is this possible?

Here’s the answer. Take any flight into Tucson at night. You’ll descend over streets evenly lit by regular sodium circles. The city is well-lighted. So what’s different from other cities? Then you figure it out. No lights glare UP, at you in the plane. Street-lights aim DOWN, at the road, and wear hats to stop light from traveling upward. Ditto for billboard lights (aimed down, not up). Car dealerships are lighted, but not blindingly. Tucson has lights. They’re just intelligently placed. They save energy, energy, & dark skies.

As a result, the countryside 5 miles outside of Tucson, AZ, is far, far darker darker than 5 miles outside my home-town of 10,000. SMART lighting, that’s the ticket. And the solution is for ordinary people to get their town councils to adopt lighting ordinances that prevent waste and reduce light pollution. Check out the noble people at Dark, and raise a ruckus down at town hall.

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