About Light Pollution

Rappahannock Astronomy Club

Presented by Scott Busby

Member, Rappahannock Astronomy Club

Introduction to Light Pollution How many Stars Can You See? Our Atmosphere Sources and Effects of Light Pollution What Can We Do About it?

Conclusion Image Showcase

Presentation Agenda

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?

•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.

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Our Atmosphere

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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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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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"Light pollution’s harmful effect on wildlife has been well-documented. 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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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.

X 10 = 1 kilowatt hour (1 Kwhr = 1000w)

• 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

Impact on Astronomical Research

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Impact on Astronomical Research

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3Without a telescope, your eyes 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

Apparentmagnitude

Number of Stars

0 4

1 15

2 48

3 171

4 513

5 1,602

6 4,800

7 14,000

Virginia Skies

Spotsy Mall

Naked Eye Visible

England Run

Belmont Obs.

W of Blueridge

What can we do About Light Pollution?

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3Several counties in the state 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.

What can we do About Light Pollution?

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Hubbell SkyCap

GE SkyGard Shield

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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2• 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.

Don’t waste energy!

Image Showcase - Moon

Image Showcase - Mars

Image Showcase - Saturn

Image Showcase - Jupiter

Image Showcase – Deep space Objects