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Light Pollution: a Primer

Light Pollution: a Primer. The basic problem: Sky Glow. Light from fixtures reflects off particles in the sky—”Sky Glow.” Large cities visible from tens of miles. The stars are not brighter here in the country—the sky is darker!. The Global Problem. Light “Made in the USA”.

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Light Pollution: a Primer

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  1. Light Pollution: a Primer

  2. The basic problem: Sky Glow • Light from fixtures reflects off particles in the sky—”Sky Glow.” • Large cities visible from tens of miles. • The stars are not brighter here in the country—the sky is darker!

  3. The Global Problem

  4. Light “Made in the USA”

  5. What’s Wrong With this Picture?

  6. Boone, 35 years ago…

  7. … today

  8. Even at Kitt Peak

  9. Charlotte… Courtesy Spencer Rackley

  10. Where does the sky glow come from? • Poor fixture design • Lack of shielding • Over-lighting • Poor installation • Market pressure

  11. Floodlights • Almost horizontal • No shielding • At night …

  12. Floodlight used in ATMs • Glare! Could you see a criminal? … • He can see you…

  13. Better: Full Cut Off (FCO) • “Shoebox” design • Why do you think they are chosen? … • Appearance in the daytime! • At night …

  14. Burger King, Tucson

  15. Even Better! • Van Gogh’s Café Terrace at Night,1888 • Experience at Tweetsie. • Result from California study: reduce glare and you can reduce the overall lighting level

  16. Sidewalk Lighting • Post-top fixtures like these here on campus are often very glaring… • … there is more to lighting than just foot-candles!

  17. Billboards: the Bad Way • Uplighted • Most light reflected into the sky • Often on all night

  18. Roadway lighting: overhead glare

  19. Cobra heads • Filament below reflector • Glaring to driver • Light polluting

  20. Better, FCO Fixtures • No light above horizon • Non-glaring to drivers, too! • May require more poles per mile • At night …

  21. “Security” Lighting • “Dusk-to-dawn” • Security or lighthouse? • Refractor very glaring and light polluting • Frequent light trespass and neighbor problem • Installed by amateurs and utilities

  22. The Glare at Night (From High, Too!)

  23. Solution: Sky Cap • GE SkyGard shown • Hubbell available • Total FCO • See results …

  24. The Capped Light at Night

  25. The Data

  26. Private Security Lights

  27. This “1973” shot impossible today! “Space Jam”

  28. Car Sales Lots • Often grossly overlit • This one at 60-110 Fc on lot, 65 on road • Use astronomically unfriendly metal halides • Can use sodium with 10% while to get color rendition

  29. Wall Packs • One of the worst fixtures for pollution as well as glare • Are available in FCO • What is the point of these? 

  30. Sports Lighting • Usually done poorly with lots of light pollution and light trespass. • Can be done well as shown here, using fixtures like ….

  31. … Musco fixtures • Costs ~$100/fixture

  32. Gas Station Canopies

  33. Compare to This • This station ~ 35fc • Large diffusers easy on the eyes • Easy on the camera, too…

  34. How You Can Help • Look at your own lights–are they needed? Could you have it capped? Put it on a switch, timer or a motion sensor. Put in a lower wattage bulb. • Where do you eat out? Do the restaurants have glaring lights? If so, complain! … • Are there some roadside lights that bother you as you try to drive? Complain!

  35. Is there a street light that shines into your window at night? Call up the utility and ask for them to put a sky cap on it. Don’t settle for simple spray painting of the fixture’s lens! • Write letters to your newspaper…. • Teach your friends about good and bad lighting–point it out when you are out with them at night. (Spoil their view…)

  36. Make a difference! Start a project to get owners of “security” lights to have sky caps installed on them. • Spend some time at www.darksky.org and become (more of) an expert! Join the IDA. • Realize that you are the ones with rights to speak for (“pursuit of Happiness” [Dec.Ind., par.2]). • Develop a local ordinance.

  37. Concluding… • Like the background on this presentation, let’s make the orange glow of sodium vapor go away.

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