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Dark-sky movement

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Title: Dark-sky movement  
Author: World Heritage Encyclopedia
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Subject: Light pollution, Urban Planning, Campaign for Dark Skies, Environmental movements, National Dark-Sky Week
Collection: Environmental Movements, Light Pollution
Publisher: World Heritage Encyclopedia

Dark-sky movement

The dark-sky movement is a campaign to reduce light pollution. The advantages of reducing light pollution include an increased number of stars visible at night, reducing the effects of unnatural lighting on the environment, and cutting down on energy usage. Earth Hour and National Dark-Sky Week are two examples of such efforts.

The movement started with professional and amateur astronomers alarmed that nocturnal skyglow from urban areas was blotting out the sight of stars. For example, the world-famous Palomar Observatory in California is threatened by sky-glow from the nearby city of Escondido and local businesses.[1] For similar reasons, astronomers in Arizona helped push the governor there to veto a bill in 2012 which would have lifted a ban on illuminated billboards.[2]

scotobiology.[3] Light pollution has also been found to affect human circadian rhythms.[4]

The dark-sky movement encourages the use of full-cutoff fixtures that cast little or no light upward in public areas and generally to encourage communities to adopt lighting regulations. A 2011 project is to establish "dark sky oasis" in suburban areas.[5]


  • Skyglow 1
  • Scotobiology 2
  • Dark-sky Preserves 3
  • International Dark-Sky Association 4
  • List of groups 5
  • See also 6
  • References 7
  • External links 8


Skyglow is the illumination of the night sky or parts of it, resembling an orange "smog". It occurs from both natural and human-made sources.[6] Artificial skyglow is caused by the over-illumination of the sky from large city centres, shopping centres, or stadiums. It consists of light that is either emitted directly upward or reflected from the ground that is then scattered by dust and gas molecules in the atmosphere, producing a luminous background or light dome. These artificial skyglows cause the sky to be 5–10 times brighter in urban areas than a naturally dark sky that is unaffected by artificial light. Natural skyglow can come from natural light sources, such as the Sun, the Moon, the stars, or auroras.

Some communities are becoming aware of this problem and are putting forth efforts to minimize the hazy, orange skyglow. A community in particular is the city of Merritt, British Columbia. An article published July 8, 2010 states that they are making minor changes to lighting in and around Merritt, such as the installment of down-cast lighting to commercial buildings, as part of their light pollution abatement program.[7] The benefits of this technological change include "saving energy through better focused lights, preserving the environment by reducing excess light that may affect flora and fauna, reducing crime and increasing safety by more adequately illuminating areas, and reducing health risks."[7]


[8] Approximately 30% of vertebrates and 60% of invertebrates are nocturnal, meaning that they depend on darkness. Their everyday behaviors are biologically evolved to adapt in uninterrupted darkness.[9]

Human health is also adversely affected by the effects of light pollution. Light during night time hours has been linked to human cancers and psychological disorders.[8]

Dark-sky Preserves

Dark-sky preserves are the main contributors to the dark-sky movement. They are a protected area found mostly in national parks that have a zero light pollution policy set in by the government and controlled by the National Dark Sky Association.

As of February 6, 2012, there was a total of 35 formally recognized dark-sky preserves recorded in the world with Canada in the lead containing 15 different preserves. These preserves are located in Nova Scotia, New Brunswick, Quebec, Ontario, Saskatchewan, Alberta and British Columbia. Other countries that have dark-sky preserves are the Czech Republic, Hungary, Poland, Slovakia, Spain, United Kingdom, and the United States. A current list of designated parks is maintained by the Dark Skies Advisory Group [10] of the International Union for Conservation of Nature (IUCN).

The parks are put in place by the Dark Sky Places program with the intention to remind us that the night sky serves just as much importance to our culture and history as our day-time sky.[11]

International Dark-Sky Association

The International Dark-Sky Association (IDA) began in 1988. A non-profit, they are responsible for the "Fixture Seal of Approval program" which offers a third party rating system judging the "sky-friendliness" of lighting fixtures and in 2009, opened a Public Policy and Government Affairs office in Washington, D.C to inform law makers and lobbyists on energy efficiency of outdoor lighting and to promote the adoption of energy saving measures.[12] The IDA has implemented several simple guidelines to responsible outdoor lighting along with some practical considerations.

  • In regards to safety, one needs only the right amount of light, in the right place, at the right time. More light often means wasted light and energy.
  • Use the lowest wattage of lamp that is feasible. The maximum wattage for most commercial applications should be 250 watts of high intensity discharge lighting, but less is usually sufficient.
  • Incorporate curfews (i.e. turn lights off automatically after a certain hour when businesses close or traffic is minimal).[13]

List of groups

See also


  1. ^ Caltech Astronomy Department
  2. ^ AZ Daily Sun: "Astronomers celebrate veto of billboard bill"
  3. ^ International society of environmental botanists: "Scotobiology – The biology of darkness"
  4. ^ International Dark Sky Association: About the IDA
  5. ^ Universe Today IDA Suburban Outreach Sites
  6. ^ Lighting Resource Centre: "What is sky glow?".
  7. ^ a b Merritt News: "Sky glow burning out?" author: Kaleena Loehr
  8. ^ a b
  9. ^ Scott R. Parker, S. L. (2011). Dark Skies, Bright Minds. Sources of Knowledge Forum, (pp. 12–17). Ontario.
  10. ^ Dark Skies Advisory Group
  11. ^ International Dark Sky Association: "International Dark Sky Places
  12. ^ International Dark Sky association: "About the IDA"
  13. ^ International Dark Sky Association: "Simple guidelines for lighting regulations. retrieved 30 December 2013

External links

  • International Dark-Sky Association
  • MyDarkSky – dark sky survey maps
  • Outdoor Lighting Regulations and Ordinances on Google Earth
  • Interactive map comparing U.S. dark sky laws
  • The dark sky movement – yahoo
  • Jasper National Park
  • Dark-sky parks of the world
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