Light Pollution and its Effects on the Night Sky

Colin Henderson

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Light PollutionWhere Does It Come From?

What is Light Pollution:• The International Dark Sky Association (IDA) defines light pollution as “Any

adverse effect of artificial light including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste”

Objects which emit light pollution:• Headlights• Street Lamps• Businesses• Houses• Neon Signs• Many More…

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Where is Light PollutionCommon places for light pollution to

become a problem:• Major cities (New York City, Tokyo,

Chicago…)• Suburbs (mainly stemming from the

nearby city)• Soon… possibly the entire earth as

the problem spreads

Areas currently most effected by light pollution:

• Nearly all of Europe is covered in light• All of Japan• Most of the United States (especially

NYC, LA, Chicago)

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Different Types of Light PollutionThree main types of light pollution:1. Clutter

– an abundance of light groups, usually poorly designed, that create confusion such as billboards or a traffic intersection

2. Glare– comes from high disparity between

illuminated and dark areas, for example having headlights shined directly in a driver’s face for a few seconds

3. Light Trespass– light trespassing unwanted into property

or other areas (ex. Neighbor’s flood light penetrating bedroom curtains

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Effects of Light Pollution on the Night SkyCause:• Light from many different sources escapes upwards towards the sky and reflects of the

particles, debris, dust and water vapor in the sky

Effects:• The light reflected off the particles in the sky causes the night sky to light up similar to

how the sun lights up the day• This prevents people from seeing stars in the night sky• Astronomers also have an issue for they cannot see as clearly as they could years ago due

to the amount of light reflecting in the sky• Astronomers rely on equipment that gathers extremely faint traces of light; “when the

entire sky is aglow, ambient light washes out the tiny points of illumination--stars, galaxies, planets--they're trying to see” (West, 2005)

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How To Fix The ProblemSimple ways of lowering light pollution emissions:• Turn off light when not using them• Only use lights when necessary• Use only full-cutoff light fixtures which shine light onto the ground and prevent

light from crossing property lines or up into the night sky

Government Involvement:• The IDA and astronomers are currently in talks with Congress to create laws

which prohibit the use of wasteful lighting being used in new buildings and the replacement of older lighting with new, more effective bulbs (West 2005)

• Programs currently being taught through schools and other venues to spread the awareness of the problem and to preach the damage of light pollution and ways to combat the issue in order to save our ability to see the stars