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Light Pollution: a Primer Dan Caton and Lee Hawkins.

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Presentation on theme: "Light Pollution: a Primer Dan Caton and Lee Hawkins."— Presentation transcript:

1 Light Pollution: a Primer Dan Caton and Lee Hawkins

2 Lighting: Opposite of Imaging What we doWhat you do

3 My Concern: our Dark Sky Observatory In the Blue Ridge Mountains of western North Carolina

4 32-inch Telescope Lab for four astronomers and their students $1M investment

5 Dome and Cline Visitor Center

6 100,000 hobbyists

7 Everyman…

8 Just as important

9 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 …

10 …The sky is darker!

11 Global Problem

12 Light “Made in the USA”

13 What’s Wrong With this Picture?

14 Closer to home You are here!

15 Boone, 40 years ago…

16 … more recently

17 Even at Kitt Peak

18 Charlotte… Courtesy Spencer Rackley, III

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

20 Floodlights Almost horizontal No shielding At night …


22 Here at the Ramada

23 Last night

24 Floodlight used in ATMs Glare! Could you see a criminal? … He can see you…

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

26 Burger King, Tucson In Boone…

27 New Advance Auto, Boone

28 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

29 Sidewalk Lighting Post-top fixtures like these on ASU campus are often very glaring… ASU has now adopted the Night Sky optics option

30 Acorns

31 Residential Post Mounts Not many FCO fixtures available This unit by Minka I recommended this to Cielo Falls, a development of ~250 “cabins” (>$850k), near our Observatory

32 More options!

33 Residential Entry Ditto: not many FCO fixtures available This unit also by Minka Soffit lights better— also do not draw bugs

34 Billboards: the Bad Way Uplighted Most light reflected into the sky Often on all night

35 Roadway lighting: overhead glare

36 Cobra heads Filament below reflector Glaring to driver Light polluting

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


39 “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

40 The Glare at Night (From High, Too!)

41 Solution: Sky Cap GE SkyGard shown Hubbell available Total FCO See results …

42 The Capped Light at Night

43 The Data

44 Private Security Lights

45 Health concerns Baby sea turtles attracted to street light Cancer and melatonin production in people

46 This “1973” shot impossible today! “Space Jam”

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

48 … like this (Tampa)

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

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

51 Fixtures with light control

52 Gas Station Canopies

53 Compare to This This station was ~ 35fc Large diffusers easy on the eyes Easy on the camera, too. Unfortunately they have slowly replaced these fixtures with the glaring type (for now, given the ordinance)

54 How You Can Help Support the creation of ordinances that require lighting to be designed and of appropriate lighting levels and glare control Steer customers to better lighting! Request better designs from lighting manufacturers—there is a real dearth of, for example, FCO driveway post top units Teach your customers and suppliers about this issue

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

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