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Outdoor LED Lighting and Dark Skies: Questions for Amateur Astronomers

    Are you an amateur astronomer? What do you think about LED street lighting and LED outdoor lighting in general?

    I want to take advantage of this blog to get some reader feedback about a topic that I can’t seem to get good handle on any other way.  I could look on astronomy social media groups, but I think I’m going to get a better perspective if the astronomers are also Electronic Design readers.  Don’t go away if you’re not into astronomy, because the astronomer’s pain could be another engineer’s opportunity.

THE BEAUTY OF SODIUM VAPOR

    Presently, as much of the world still uses sodium-vapor lights, it is my impression that astronomers are more or less satisfied with that, because it is relatively easy to filter out the two lines in the sodium spectrum.  As  we transition to LED street lights, astronomers must deal with a loom that contains the entire spectrum of sunlight.

    When I bring up the subject of outdoor LED lighting and astronomy in the LED community, the feedback I get is that the virtue of LED lighting is the way it lets you control where the photons go.  People explain that the nature of the technology allows the illumination to be placed very precisely on whatever objects are to be illuminated, rather than splashing it all over the place.  

   I’m not ready to accept that. To me, this seems to evade the question of what happens to the photons after they strike the object being illuminated and bounce off in all directions.  

    I used the term, loom deliberately above.  I learned the word as a sailor’s term for the nighttime glow of a far-off town beyond the distant horizon, across the stretch of open sea. That’s very romantic,  but I think the term is used in a similar sense in astronomy, and it’s not so heart-warming as a manifestation of  a sailor’s return to a home port.

I NEVER REALLY SAW THE SKY

    I am inclined to think that loom is a problem.  I grew up near New York City, and I don’t believe that in the first 20 years of my life, I ever actually saw the night sky – until I spent a frigid moonless night in November camped out near Lake Champlain.  When I wasn't shivering, it was breathtaking, and it gave me a sense of what astronomers must feel and be driven by.

    So as nice as it is that LED luminaires can be designed to apply light in very precise patterns, that doesn’t settle the issue.  It’s like the optical version of second-hand smoke. (I gather that even Kitt Peak is bothered by the loom of Phoenix.) Unless. . . .

LATERAL THINKING: LESS REALLY CAN BE MORE

    The keynote speech at an LED conference put on by Cree and Arrow last December had an interesting theme: briefly, it was: “What’s the best thing you can do with LED lighting?  Turn it off.”  Among the speaker’s points was that North American cities are unnecessarily over-lit. Cities and business owners could save money and energy companies could achieve load-balancing if we could turn off the lights we don't need. As it turns out, that's even cool with the security folks, as long as there's proximity/motion sensing.

    I think that the a real advantage of LED outdoor lighting for optical astronomers is probably its controllability.  LEDs are easy to turn on and off, compared to lights that use high-temperature plasmas.

The idea is that, with proximity and remote control for outdoor LED lighting, there could be symbiotic relationships between cities and astronomers in which remotely controlled street lamps could be selectively turned off or put on proximity control in certain parts of the city during hours when few people were about. 

IS THAT GOING TO WORK?

    I care whether that kind of thing could work for big-time astronomers and for the folks I've worked beside who have spent many dark nights backyard observatories or camped out next to homemade Dobsonians in the far reaches of state and national parks.  Maybe my thoughts are morse with the latter, because they're the ones I can reach through a blog on Electronic Design's Website.  If I've kept your interest this far, please take another minute or two to scroll down to the comments section and let me know what you think.

TAGS: Lighting Power
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