World Library  
Flag as Inappropriate
Email this Article

National Dark-Sky Week

National Dark-Sky Week (NDSW)
Status Active
Genre Astronomy-related events and competitions
Frequency Week of the new moon in April
Location(s) Worldwide
Inaugurated 2003
Founder Jennifer Barlow
Most recent 2015

National Dark-Sky Week (NDSW), held during the week of the new moon in April,[1] is a week during which people worldwide turn out their lights in order to observe the beauty of the night sky without light pollution. This event was founded in 2003 by high school student Jennifer Barlow of Midlothian, Virginia and its popularity and participation increases every year. It has been endorsed by the International Dark-Sky Association (IDA), the American Astronomical Society (AAS), the Astronomical League, and Sky & Telescope (S&T).[2]


  • Goal 1
  • Participation 2
  • Types of Light Pollution 3
  • Implications of Light Pollution 4
  • Event dates 5
  • See also 6
  • References 7
  • External links 8


The goals of the event are to:

  • Temporarily reduce light pollution and raise awareness about its effects on the night sky,
  • Encourage the use of better lighting systems that direct light downward instead of into the sky, and
  • Promote the study of astronomy.

This event always occurs in April, during the week of the New moon so that the sky can be as dark as possible for optimum viewing conditions.

Jennifer Barlow states, "The night sky is a gift of such tremendous beauty that should not be hidden under a blanket of wasted light. It should be visible so that future generations do not lose touch with the wonder of our universe." Barlow explains, "It is my wish that people see the night sky in all of its glory, without excess light in the sky as our ancestors saw it hundreds of years ago."[2]


Willing participants in this project turn off all unnecessary lighting indoors and outdoors sources in order to reduce light pollution of the night sky.

The International Dark-sky Association encourages light users to take precautions against outdoor light pollution by:[3]

  • Using outdoors light only when needed
  • Confine light to specific areas
  • Beware that lights are only as bright as it is necessary
  • Reducing the amount of blue light emissions used
  • Use lighting that faces downward, in order to avoid over illumination- called fully shielded fixtures

Types of Light Pollution

Types of light pollution include skyglow, a hazy glow produced by the reflection water molecules in the air that encompasses cities which prevent the night sky to be fully seen. Light trespass is a condition in which light is oriented into areas in which it is not needed. A common example is street lighting projecting in all directions including the sky which creates a hazy reflection upon the night sky, making it difficult for star observation.[4]

Implications of Light Pollution

Light pollution is the adverse affects of artificial light.[5]

Affected parties of light pollution include:[6]


By increasing the number of participants, the quality of viewing the sky and stars will be temporarily improved. This is a benefit to astronomers that are faced with light pollution issues such as light trespass and skyglow.[4]

Nocturnal Wildlife:
Several animals have been documented to be affected by light pollution. The glare of street lights because distraction to nocturnal birds in flight leading to bird crashes into sky scrapers and buildings. The use of light may also cause bird to reproduce or migrate too early. The feeding behavior of insects, bats, sea turtles, fish, replies reflect alterations by artificial light. Sea turtles mistake the glow of electric lights for the shimmer of the ocean, leading them to flock outside of their nest into hazardous areas.

Human Circadian rhythm and sleep patterns:

Exposure to light during traditional sleeping hours have are documented to cause disruptions in the circadian rhythm that regulate human sleep cycles.[6]

Growth Patterns of Plants and Trees:

The growing pattern of trees have been disrupted and less adjusted to seasonal changes in weather and light.[6]

Event dates

Timeline of Dark Sky Week events
Sr. Year Week New Moon Notes Reference
1 2003 1 April 2003 UTC
2 2004 19 April 2004 UTC
3 2005 8 April 2005 UTC
4 2006 27 April 2006 UTC
5 2007 17 April 2007 UTC
6 2008 6 April 2008 UTC In 2008, the organizers coordinated the week with Earth Hour. [1]
7 2009 April 20–26, 2009 25 April 2009 UTC International Year of Astronomy (IYA 2009)
In 2009, the United States Dark Sky Week becomes International Dark Sky Week
8 2010 April 4–10, 2010 13–14 April 2010 UTC [9][10]
9 2011 3 April 2011 UTC
10 2012 21 April 2012 UTC
11 2013 10 April 2013 UTC
12 2014 April 20–26, 2014 29 April 2014 UTC [11]
13 2015 April 13–18, 2015 18 April 2015 UTC International Year of Light and Light-based Technologies (IYL 2015)
  indicates upcoming event

See also


  1. ^ a b "What Is National Dark Sky Week?". Wise Geek. Conjecture Corporation. Retrieved 25 December 2013. 
  2. ^ a b Bobra, Monica. "Jennifer Barlow: Dark-sky Devotee".  
  3. ^ "Outdoor Lighting Basics". International Dark-Sky Association (in en-US). Retrieved 2015-10-22. 
  4. ^ a b "Light Pollution Impacts Animals and Environment". Retrieved 2015-10-22. 
  5. ^ "Light Pollution Impacts Animals and Environment". Retrieved 2015-10-20. 
  6. ^ a b c Chepesiuk, Ron (2009-01-01). "Missing the Dark: Health Effects of Light Pollution". Environmental Health Perspectives 117 (1): A20–A27.  
  7. ^ "International Dark Sky Week". Astronomers Without Borders. AWB. Retrieved 20 October 2015. 
  8. ^ "International Dark Sky Week". Astronomers Without Borders. Retrieved 20 October 2015. 
  9. ^ "International Dark Sky Week". Astronomers Without Borders. AWB. Retrieved 25 December 2013. 
  10. ^ "How to participate in International Dark-Sky Week". Dark Skies Awareness. Retrieved 25 December 2013. 
  11. ^ "International Dark Sky Week April 20-26, 2014". Dark Sky. IDA. Retrieved 25 December 2013. 

External links

  • "National Dark-Sky Week".  
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from Hawaii eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.