About Light Pollution
Rappahannock Astronomy Club
Presented by Scott Busby
Member, Rappahannock Astronomy Club
Presentation Agenda
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Introduction to Light Pollution
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How many Stars Can You See?
Our Atmosphere
Sources and Effects of Light Pollution
What Can We Do About it?
Conclusion
Image Showcase
What is Light Pollution?
Urban light pollution and light trespass has a drastic effect on our
environment and should be regulated through implementing strong lighting
ordinances. It destroys our view of the night sky and directly contributes to a
decrease in some animal and plant populations. It also has a marked
detrimental effect on astronomic research.
How many Stars Can you See?
1
2
3
•The night sky at the Black Forest Star Party in
Cherry Springs, PA.
•The night sky at Batsto, NJ. This is a
moderately dark-sky site with some light
pollution.
•The night sky at an suburban park in
Voorhees, NJ.
Our Atmosphere
1
3
2
The composition of the atmosphere is 79% nitrogen, 20% oxygen, and 1% other gases. These gases are the constituents
of water vapor that forms clouds and it also combines with obscurants like dust and smoke. Carbon dioxide is also
prevalent as a natural occurring gas or it is the result of pollution from human industrial activities and automobiles. These
gases and pollutants when combined tend to filter out all but the brightest of stars visible to us from earth's surface and
reflect lights from the ground.
The Incandescent light bulb
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3
2
Since the industrial revolution the amount of light pollution in the atmosphere has increased
exponentially with the invention of the incandescent light bulb. Advances in electrical lighting
technologies occurring during the latter 20th century have resulted in a remarkable increase
in the illumination of our cities, businesses, and homes. These technologies like florescent
tubes, halogen and halide fixtures, sodium and mercury based lighting and other types light
our path through the night.
Effect on the Natural Environment
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3
2
"Light pollution’s harmful effect on wildlife has been welldocumented. It disturbs the breeding cycles of animals, stunts
the growth of certain flora and fauna, and in some animals, even
affects the production of hormones regulating everything from
fat storage to egg production."
Energy Consumption
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3
X 10 = 1 kilowatt hour (1 Kwhr = 1000w)
2
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Number of hours/yr: 4170
Lamp life: 1000 hours X 4 bulbs
operating cost $41.91
kWh / yr: 417
Carbon Dioxide emission: 583 pounds
Sulphur Dioxide emissions: 7 pounds
Nitrous Oxide emissions: 4 pounds
Mercury released/yr: 4 ounces
Coal used: 196 pounds
Emission equivalent (same as driving): 475 miles
Number of trees to null effects: 1
Light pollution or the creation of it, causes another problem that needs addressing.
Artificial lighting requires electricity that is produced by the consumption of fossil fuels.
Burning of fossil fuels adds pollutants to the atmosphere by introducing particulates
and greenhouse gases. This results in the increase of carbon dioxide which
contributes to global warming.
Impact on Astronomical Research
1
2
3
Impact on Astronomical Research
1
Without a telescope, your eyes 3
can just barely see magnitude 6
stars. The distant planet Pluto is magnitude 14, so you definitely
need a telescope to see it. The best telescopes on Earth can spot
stars with magnitudes between 25 and 27. The Hubble Space
Telescope can sometimes "see" magnitude 30 stars.
Number of stars brighter than magnitude
Apparent
Number
2
magnitude
of Stars
0
4
1
15
2
48
3
171
4
513
Naked Eye Visible
5
1,602
6
4,800
7
14,000
Spotsy Mall
England Run
Virginia Skies
Belmont Obs.
W of Blueridge
What can we do About Light
Pollution?
1 Several counties in the state
3
of Virginia have already
enacted lighting ordinances that restrict wasteful lighting.
Most lighting ordinances identify the most bothersome
types of lighting and limit them in numbers, maximum
wattage output, spectrum, height above the ground,
timed illumination and horizontal emission.
2
What can we do About Light
Pollution?
1
Hubbell SkyCap
2
GE SkyGard Shield
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Conclusion
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Hundreds of amateur Astronomy clubs have also instituted
programs that increase public awareness and show how to
reduce the overall impact of light pollution. As for your help, it is
quite simple, reduce light pollution by following a few simple
rules:
Conclusion
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Don’t waste energy!
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• Turn exterior lights off between the hours of 10pm and 5am.
• Reduce output of outdoor security lights and porch lights by
using lower wattage bulbs.
• Shield outdoor flood lights so they illuminate the ground
beneath them and not a large area around them.
• Put driveway flood lights on a timer or use motion sensor lights.
• Remove, turnoff, or shield pole mounted security lights.
Image Showcase - Moon
Image Showcase - Mars
Image Showcase - Saturn
Image Showcase - Jupiter
Image Showcase –
Deep space Objects