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{{Infobox research project
[[File:Earthlights dmsp.jpg|thumb|Artificial lights strongly overlap with the concentrations of Earth's population, showing the locations of [[light pollution]].]]
| name = Globe at Night
| title =
| image = File:City Lights 2012 - Flat map crop.jpg
| image_alt = Artificial lights showing the locations of [[light pollution]] in October 2012.
| caption = Artificial lights showing the locations of [[light pollution]] in October 2012.
| keywords = [[Light Pollution]], [[Astronomy]], [[Scotobiology]], [[Citizen Science]], [[Crowdsourcing]]
| project_type =
| funding_agency = [[National Science Foundation]] via [[NOIRLab]]
| sponsors =
| framework_programme =
| project_reference =
| research_objective = Measuring and raising awareness of artificial light pollution
| location =
| coordinator = [[Association of Universities for Research in Astronomy|AURA]], [[Connie Walker (astronomer)|Connie Walker]]
| participants =
| partners = [[International Dark-Sky Association]], CADIAS
| budget =
| funding =
| start = 2006
| end =
| website = {{Official website}}
}}


'''Globe at Night''' is an international scientific research program that [[crowdsource]]s measurements of [[light pollution]] in the night sky. At set time periods within each year, the project asks people to count the number of stars that they can see from their location and report it to the project's website. The coordinating researchers compile this information to produce a public, freely available map of global light pollution. By September 2011, almost 70,000 measurements had been made.<ref name=ng/> The use of data collected by the public makes the program an example of [[citizen science]].<ref name=SciRep>{{cite journal|last=Kyba|first=Christopher C. M.|author2=Wagner, Janna M. |author3=Kuechly, Helga U. |author4=Walker, Constance E. |author5=Elvidge, Christopher D. |author6=Falchi, Fabio |author7=Ruhtz, Thomas |author8=Fischer, Jürgen |author9= Hölker, Franz |title=Citizen Science Provides Valuable Data for Monitoring Global Night Sky Luminance|journal=Scientific Reports|date=16 May 2013|volume=3|doi=10.1038/srep01835|bibcode = 2013NatSR...3E1835K }}</ref> Globe at Night began as a [[NASA]] educational program in the US organized by the [[NOAO]], and was expanded internationally during the 2009 [[International Year of Astronomy]];<ref name=spie>{{cite journal|last=Walker|first=Constance|author2=Stephen Pompea|title=Global campaign to save energy and fight light pollution|journal=SPIE Newsroom|date=3 November 2010|doi=10.1117/2.1201009.003213}}</ref> it is an offshoot of the [[GLOBE Program]], which focusses on school-based science education.
'''Globe at Night''' is an international scientific research program that [[crowdsource]]s measurements of [[light pollution]] in the night sky. At set time periods within each year, the project asks people to count the number of stars that they can see from their location and report it to the project's website. The coordinating researchers compile this information to produce a public, freely available map of global light pollution. By September 2011, almost 70,000 measurements had been made.<ref name=ng/> The use of data collected by the public makes the program an example of [[citizen science]].<ref name=SciRep>{{cite journal|last=Kyba|first=Christopher C. M.|author2=Wagner, Janna M. |author3=Kuechly, Helga U. |author4=Walker, Constance E. |author5=Elvidge, Christopher D. |author6=Falchi, Fabio |author7=Ruhtz, Thomas |author8=Fischer, Jürgen |author9= Hölker, Franz |title=Citizen Science Provides Valuable Data for Monitoring Global Night Sky Luminance|journal=Scientific Reports|date=16 May 2013|volume=3|pages=1835|doi=10.1038/srep01835|bibcode = 2013NatSR...3E1835K |pmid=23677222 |pmc=3655480}}</ref> Globe at Night began as a [[NASA]] educational program in the US organized by the [[NOAO]], and was expanded internationally during the 2009 [[International Year of Astronomy]];<ref name=spie>{{cite journal|last=Walker|first=Constance|author2=Stephen Pompea|title=Global campaign to save energy and fight light pollution|journal=SPIE Newsroom|date=3 November 2010|doi=10.1117/2.1201009.003213}}</ref> it is an offshoot of the [[GLOBE Program]], which focuses on school-based science education.


== Scientific rationale ==
== Scientific rationale ==
[[File:Pont-canal de Briare Lamiot Pollution lumineuse4.jpg|thumb|Artificial lights attract many insects, to the advantage of some spiders, as on this lighted bridge over the [[Loire River]], France. These changes in behavior can then affect [[food webs]] and cause further [[knock-on effect]]s.]]
[[File:Pont-canal de Briare Lamiot Pollution lumineuse4.jpg|thumb|Artificial lights attract many insects, to the advantage of some spiders, as on this lighted bridge over the [[Loire River]], France. These changes in behavior can then affect [[food webs]] and cause further [[knock-on effect]]s.]]


[[Light pollution]], the introduction of artificial light into formerly dark ecosystems, has numerous [[ecological light pollution|adverse ecological effects]]. Exposure to artificial light can prove fatal for some organisms (e.g. moths that fly into a burning flame), can interrupt a life cycle phase for others (e.g. [[glowworm]]s are unable to attract mates), and can reduce the possibilities for finding food (because of increased risk of predation).<ref>{{cite book|author=Catherine Rich and Travis Longcore|title=Ecological consequences of artificial night lighting|publisher=Island Press|date=2006|isbn=1-55963-128-7}}</ref> Light at night can also interfere with the [[chronobiology]] of many animals, including humans, through suppression of [[melatonin]] secretion.<ref name=navara>{{cite journal|last=Navara|first=KJ|author2=Nelson|title=The dark side of light at night: physiological, epidemiological, and ecological consequences|journal=J Pineal Res|date=2007|volume=43|pages=215–224|doi=10.1111/j.1600-079X.2007.00473.x|pmid=17803517}}</ref>
[[Light pollution]], the introduction of artificial light into formerly dark ecosystems, has numerous [[ecological light pollution|adverse ecological effects]]. Exposure to artificial light can prove fatal for some organisms (e.g. moths that fly into a burning flame), can interrupt a life cycle phase for others (e.g. [[glowworm]]s are unable to attract mates), and can reduce the possibilities for finding food (because of increased risk of predation).<ref>{{cite book|author=Rich, Catherine and Longcore, Travis |title=Ecological consequences of artificial night lighting|publisher=Island Press|date=2006|isbn=978-1-55963-128-0}}</ref> Light at night can also interfere with the [[chronobiology]] of many animals, including humans, through suppression of [[melatonin]] secretion.<ref name=navara>{{cite journal|last=Navara|first=KJ|author2=Nelson|title=The dark side of light at night: physiological, epidemiological, and ecological consequences|journal=J Pineal Res|date=2007|volume=43|issue=3|pages=215–224|doi=10.1111/j.1600-079X.2007.00473.x|pmid=17803517|doi-access=free}}</ref>


There are also cultural and economic reasons for concern about [[over-illumination|excessive light]] at night. [[Skyglow]] prevents large fractions of the Earth's population from viewing the [[Milky Way Galaxy|Milky Way]],<ref>{{cite journal
There are also cultural and economic reasons for concern about [[over-illumination|excessive light]] at night. [[Skyglow]] prevents large fractions of the Earth's population from viewing the [[Milky Way Galaxy|Milky Way]],<ref>{{cite journal
|author=P. Cinzano and F. Falchi and C. D. Elvidge
|author1= Cinzano, P. |author2=Falchi, F. |author3=Elvidge, C. D.
⚫
|title = The first world atlas of the artificial night sky brightness
|url = http://debora.pd.astro.it/cinzano/download/0108052.pdf
⚫
|journal = Mon. Not. R. Astron. Soc.
⚫
| title = The first world atlas of the artificial night sky brightness
|volume = 328
⚫
|journal=Mon.Not.Roy.Astron.Soc.
|volume=328|date=2001|pages=689–707
|date = 2001
|pages = 689–707
|doi = 10.1046/j.1365-8711.2001.04882.x
|doi = 10.1046/j.1365-8711.2001.04882.x
|issue=3
|issue = 3
⚫
|arxiv = astro-ph/0108052 |bibcode = 2001MNRAS.328..689C }}</ref> which drove the development of much of ancient science, mythology, and religion. In the US, the cost of generating wasted light is estimated to be 7 billion US dollars per year;<ref>{{cite journal|last=Gallaway|first=Terrel|author2=Olsen, Reed N. |author3=Mitchell, David M. |title=The economics of global light pollution|journal=Ecological Economics|volume=69|issue=3|pages=658–665|doi=10.1016/j.ecolecon.2009.10.003}}</ref> the production of the electricity for this wasted light also results in the release of chemical pollution and [[greenhouse gases]].
|doi-access=free |arxiv = astro-ph/0108052
|bibcode = 2001MNRAS.328..689C
⚫
|s2cid=15365532 }}</ref> which drove the development of much of ancient science, mythology, and religion. In the US, the cost of generating wasted light is estimated to be 7 billion US dollars per year;<ref>{{cite journal|last=Gallaway|first=Terrel|author2=Olsen, Reed N. |author3=Mitchell, David M. |title=The economics of global light pollution|journal=Ecological Economics|volume=69|issue=3|pages=658–665|doi=10.1016/j.ecolecon.2009.10.003|year=2010}}</ref> the production of the electricity for this wasted light also results in the release of chemical pollution and [[greenhouse gases]].


The Globe at Night project has two main goals: raise public awareness of light pollution and its effects, and provide global mapping data for light pollution.<ref name=ng/><ref name=gan_mainpage>{{cite web|title=Globe at Night - Home page|url=http://www.globeatnight.org/|publisher=Globe at Night|accessdate=14 March 2012}}</ref><ref name=gan_analyze>{{cite web|title=Globe at Night - Analyze|url=http://www.globeatnight.org/analyze.html|publisher=Globe at Night|accessdate=14 March 2012}}</ref>
The Globe at Night project has two main goals: raise public awareness of light pollution and its effects, and provide global mapping data for light pollution.<ref name=ng/><ref name=gan_mainpage>{{cite web|title=Globe at Night - Home page|url=http://www.globeatnight.org/|publisher=Globe at Night|access-date=14 March 2012}}</ref><ref name=gan_analyze>{{cite web|title=Globe at Night - Analyze|url=http://www.globeatnight.org/analyze.html|publisher=Globe at Night|access-date=14 March 2012}}</ref>


== Method ==
== Method ==
[[File:Light pollution It's not pretty.jpg|thumb|The visibility of the constellation [[Orion (constellation)|Orion]] varies depending on the observer's local level of light pollution; clear sky is on left, light-polluted sky is on right. Note that the photo at left shows more detail than can be seen with the human eye.]]
[[File:Light pollution It's not pretty.jpg|thumb|The visibility of the constellation [[Orion (constellation)|Orion]] varies depending on the observer's local level of light pollution; clear sky is on left, light-polluted sky is on right. Note that the photo at left shows more detail than can be seen with the human eye.]]


The project asks members of the public to go outside on dark moonless nights and report how many stars are visible in particular [[constellation]]s.<ref name=ng/><ref name=spie/> The project focuses on students, teachers, and families, and has produced activity packets in 13 languages.<ref name=spie/><ref name=gan_activity_pack>{{cite web|title=Globe at Night Family Activity Packet|url=http://www.globeatnight.org/observe.html|publisher=Globe at Night|accessdate=14 March 2012}}</ref> NASA encourages students in its [[NASA INSPIRE|INSPIRE]] program to participate.<ref>http://nasaed.okstate.edu/INSPIRE/enewsarchives/April23_12.html</ref>
The project asks members of the public to go outside on dark moonless nights and report how many stars are visible in particular [[constellation]]s.<ref name=ng/><ref name=spie/> The project focuses on students, teachers, and families, and has produced activity packets in 13 languages.<ref name=spie/><ref name=gan_activity_pack>{{cite web|title=Globe at Night Family Activity Packet|url=http://www.globeatnight.org/observe.html|publisher=Globe at Night|access-date=14 March 2012|archive-date=3 November 2013|archive-url=https://web.archive.org/web/20131103152537/http://www.globeatnight.org/observe.html|url-status=dead}}</ref> NASA encourages students in its [[NASA INSPIRE|INSPIRE]] program to participate.<ref>{{Cite web |url=http://nasaed.okstate.edu/INSPIRE/enewsarchives/April23_12.html |title=EINSPIRE Communication |access-date=2013-04-29 |archive-url=https://web.archive.org/web/20130706110828/http://nasaed.okstate.edu/INSPIRE/enewsarchives/April23_12.html |archive-date=2013-07-06 |url-status=dead }}</ref>


Participating individuals are asked to go outside on specified dates at least an hour after sunset, let their eyes adjust to the [[available light|ambient light]] level, and observe a specific constellation: Orion or [[Leo (constellation)|Leo]] in the Northern Hemisphere, [[Crux]] in the Southern Hemisphere.<ref name=gan_mainpage/><ref name=gan_activity_pack/><ref>{{cite web|last=NASA Education Office|title=Join the Worldwide Globe at Night 2012 Campaign|url=http://www.spaceref.com/news/viewsr.rss.html?pid=40248&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+spaceref%2Fjext+%28SpaceRef+-+Space+News+as+it+Happens%29&utm_content=Google+International|publisher=spaceref.com|accessdate=15 March 2012}}</ref> The choice of a two-week span of dates near the [[new moon]] removes any effect on sky brightness from [[Rayleigh scattering|scattered moonlight]], and observing well after sunset prevents any lingering light from twilight.<ref name=Weaver/> By comparing the stars they see with [[star chart]]s showing stellar visibility under different light pollution conditions, they qualitatively measure light pollution.<ref name=sandt/><ref>{{cite web|title=Globe at Night - Magnitude Charts Orion 40 deg N|url=http://www.globeatnight.org/observe_magnitude_orion.html|publisher=Globe at Night|accessdate=14 March 2012}}</ref> Stellar visibility can also be measured for the project using a [[Sky Quality Meter]], a tool used by [[amateur astronomer]]s.<ref name=sandt>{{cite web|last=Beatty|first=Kelly|title=Make the Effort for "Globe at Night"|url=http://www.skyandtelescope.com/observing/highlights/Make-the-Effort-for-Globe-at-Night-137690488.html|publisher=Sky & Telescope|accessdate=25 January 2012}}</ref> These light pollution data are then submitted to the coordinating website via a web browser.<ref name=nsf>{{cite web|title=NSF Current Newsletter - March 2012|url=http://www.nsf.gov/news/newsletter/mar_12/index.jsp#ripple2|publisher=National Science Foundation|accessdate=15 March 2012}}</ref><ref name=gan_webapp>{{cite web|title=Globe at Night webapp|url=http://www.globeatnight.org/webapp/|publisher=Globe at Night|accessdate=14 March 2012}}</ref> The assembled data are provided to researchers and the public via a mapping interface that displays the data overlaid on [[Google Maps]].<ref name=gan_map>{{cite web|url=http://www.globeatnight.org/map/|publisher=Globe at Night|title=Globe at Night Interactive Map viewer|accessdate=14 March 2012}}</ref>
Participating individuals are asked to go outside on specified dates at least an hour after sunset, then let their eyes adjust to the [[available light|ambient light]] level, and observe a specific constellation: Orion or [[Leo (constellation)|Leo]] in the Northern Hemisphere, [[Crux]] in the Southern Hemisphere.<ref name=gan_mainpage/><ref name=gan_activity_pack/><ref>{{cite web|last=NASA Education Office|title=Join the Worldwide Globe at Night 2012 Campaign|url=http://www.spaceref.com/news/viewsr.rss.html?pid=40248|publisher=spaceref.com|access-date=15 March 2012}}{{Dead link|date=June 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref> The choice of a two-week span of dates near the [[new moon]] removes any effect on sky brightness from [[Rayleigh scattering|scattered moonlight]], and observing well after sunset prevents any lingering light from twilight.<ref name=Weaver/> By comparing the stars they see with [[star chart]]s showing stellar visibility under different light pollution conditions, they qualitatively measure light pollution.<ref name=sandt/><ref>{{cite web|title=Globe at Night - Magnitude Charts Orion 40 deg N|url=http://www.globeatnight.org/observe_magnitude_orion.html|publisher=Globe at Night|access-date=14 March 2012}}</ref> Stellar visibility can also be measured for the project using a [[Sky Quality Meter]], a tool used by [[amateur astronomer]]s.<ref name=sandt>{{cite web|last=Beatty|first=Kelly|title=Make the Effort for "Globe at Night"|url=http://www.skyandtelescope.com/observing/highlights/Make-the-Effort-for-Globe-at-Night-137690488.html|publisher=Sky & Telescope|access-date=25 January 2012|archive-url=https://archive.today/20130202105850/http://www.skyandtelescope.com/observing/highlights/Make-the-Effort-for-Globe-at-Night-137690488.html|archive-date=2 February 2013|url-status=dead}}</ref> These light pollution data are then submitted to the coordinating website via a web browser.<ref name=nsf>{{cite web |title=NSF Current Newsletter - March 2012 |url=https://www.nsf.gov/news/newsletter/mar_12/index.jsp#ripple2 |publisher=National Science Foundation |access-date=15 March 2012 |url-status=dead |archive-url=https://web.archive.org/web/20120310002938/https://www.nsf.gov/news/newsletter/mar_12/index.jsp#ripple2 |archive-date=10 March 2012 }}</ref><ref name=gan_webapp>{{cite web|title=Globe at Night webapp|url=http://www.globeatnight.org/webapp/|publisher=Globe at Night|access-date=14 March 2012}}</ref> The assembled data are provided to researchers and the public via a mapping interface that displays the data overlaid on [[Google Maps]].<ref name=gan_map>{{cite web|url=http://www.globeatnight.org/map/|publisher=Globe at Night|title=Globe at Night Interactive Map viewer|access-date=14 March 2012}}</ref>


With this technique, observers are reporting a naked eye [[limiting magnitude]] (NELM) between 1 and 7. Humans are able to observe stars below 7th magnitude, although this may require blocking out other sources of light.<ref name=Weaver>{{cite journal|last=Weaver|first=Harold F.|title=The Visibility of Stars Without Optical Aid|journal=Publications of the Astronomical Society of the Pacific|date=1947|volume=59|issue=350|pages=232|url=http://articles.adsabs.harvard.edu/full/1947PASP...59..232W/0000232.000.html|accessdate=12 March 2012|bibcode = 1947PASP...59..232W |doi = 10.1086/125956 }}</ref> Under clear, unpolluted skies, the measurement of NELM should be strongly correlated with the level of light pollution. Other factors, particularly those that reduce the [[astronomical seeing|seeing]], can reduce NELM:<ref name=Weaver/>
With this technique, observers are reporting a naked eye [[limiting magnitude]] (NELM) between 1 and 7. Humans are able to observe stars below 7th magnitude, although this may require blocking out other sources of light.<ref name=Weaver>{{cite journal|last=Weaver|first=Harold F.|title=The Visibility of Stars Without Optical Aid|journal=Publications of the Astronomical Society of the Pacific|date=1947|volume=59|issue=350|pages=232|bibcode = 1947PASP...59..232W |doi = 10.1086/125956 |doi-access=free}}</ref> Under clear, unpolluted skies, the measurement of NELM should be strongly correlated with the level of light pollution. Other factors, particularly those that reduce the [[astronomical seeing|seeing]], can reduce NELM:<ref name=Weaver/>
* atmospheric [[water content]] (especially clouds)<ref>{{cite journal |last=Kyba|first=Christopher C. M. |last2=Ruhtz|first2=Thomas |last3=Fischer|first3=Jürgen |last4=Hölker|first4=Franz |title=Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems|journal=PLoS ONE|volume=6|issue=3|pages=e17307|doi=10.1371/journal.pone.0017307|pmid=21399694|pmc=3047560|bibcode = 2011PLoSO...617307K |url=http://adsabs.harvard.edu/abs/2011PLoSO...617307K }}</ref>
* atmospheric [[water content]] (especially clouds)<ref>{{cite journal |last1=Kyba|first1=Christopher C. M. |last2=Ruhtz|first2=Thomas |last3=Fischer|first3=Jürgen |last4=Hölker|first4=Franz |title=Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems|journal=PLOS ONE|volume=6|issue=3|pages=e17307|doi=10.1371/journal.pone.0017307|pmid=21399694|pmc=3047560|bibcode=2011PLoSO...617307K |year=2011 |doi-access=free }}</ref>
* atmospheric [[aerosols]] such as dust or air pollution<ref>{{cite journal|last=Garstang|first=R. H.|title=Dust and light pollution|journal=Publications of the Astronomical Society of the Pacific|date=October 1991|volume=103|pages=1109–1116|url=http://adsabs.harvard.edu/full/1991PASP..103.1109G|accessdate=12 March 2012|bibcode = 1991PASP..103.1109G |doi = 10.1086/132933 }}</ref>
* atmospheric [[aerosols]] such as dust or air pollution<ref>{{cite journal|last=Garstang|first=R. H.|title=Dust and light pollution|journal=Publications of the Astronomical Society of the Pacific|date=October 1991|volume=103|pages=1109–1116|bibcode = 1991PASP..103.1109G |doi = 10.1086/132933 |s2cid=121416771 }}</ref>
* [[visual acuity]] of the observer<ref>{{cite journal|last=Westheimer|first=G|title=Visual Acuity|journal=Annual Review of Psychology|date=1 January 1965|volume=16|issue=1|pages=359–380|doi=10.1146/annurev.ps.16.020165.002043}}</ref>
* [[visual acuity]] of the observer<ref>{{cite journal|last=Westheimer|first=G|title=Visual Acuity|journal=Annual Review of Psychology|date=1 January 1965|volume=16|issue=1|pages=359–380|doi=10.1146/annurev.ps.16.020165.002043|pmid=14268891}}</ref>
* wind (can cause stars to [[scintillation (astronomy)|twinkle]], and render dim stars invisible)
* wind (can cause stars to [[scintillation (astronomy)|twinkle]], and render dim stars invisible)
* [[Aurora (astronomy)|aurora]]
* [[Aurora (astronomy)|aurora]]
* [[airglow]],<ref>{{cite journal|last=Broadfoot|first=A. Lyle|author2=Kendall, Kenneth R.|title=The Airglow Spectrum, 3100-10,000 A|journal=Journal of Geophysical Research|date=1 January 1968|volume=73|issue=1|pages=426–428|doi=10.1029/JA073i001p00426|bibcode = 1968JGR....73..426B }}</ref> [[gegenschein]], and [[Zodiacal light]]<ref>{{cite journal|last=James|first=J. F.|author2=Mukai, T. |author3=Watanabe, T. |author4=Ishiguro, M. |author5=Nakamura, R. |title=The morphology and brightness of the zodiacal light and gegenschein|journal=[[Monthly Notices of the Royal Astronomical Society]]|date=1997|volume=288|issue=4|pages=1022–1026|url=http://adsabs.harvard.edu/abs/1997MNRAS.288.1022J|accessdate=12 March 2012|bibcode = 1997MNRAS.288.1022J |doi=10.1093/mnras/288.4.1022}}</ref>
* [[airglow]],<ref>{{cite journal|last=Broadfoot|first=A. Lyle|author2=Kendall, Kenneth R.|title=The Airglow Spectrum, 3100-10,000 A|journal=Journal of Geophysical Research|date=1 January 1968|volume=73|issue=1|pages=426–428|doi=10.1029/JA073i001p00426|bibcode = 1968JGR....73..426B }}</ref> [[gegenschein]], and [[Zodiacal light]]<ref>{{cite journal|last=James|first=J. F.|author2=Mukai, T. |author3=Watanabe, T. |author4=Ishiguro, M. |author5=Nakamura, R. |title=The morphology and brightness of the zodiacal light and gegenschein|journal=[[Monthly Notices of the Royal Astronomical Society]]|date=1997|volume=288|issue=4|pages=1022–1026|bibcode = 1997MNRAS.288.1022J |doi=10.1093/mnras/288.4.1022|doi-access=free}}</ref>
* age of the observer<ref>{{cite journal|last=Gittings|first=Neil S.|author2=Fozard, James L.|title=Age related changes in visual acuity|journal=Experimental Gerontology|volume=21|issue=4-5|pages=423–433|doi=10.1016/0531-5565(86)90047-1}}</ref>
* age of the observer<ref>{{cite journal|last=Gittings|first=Neil S.|author2=Fozard, James L.|title=Age related changes in visual acuity|journal=Experimental Gerontology|volume=21|issue=4–5|pages=423–433|doi=10.1016/0531-5565(86)90047-1|year=1986|pmid=3493168|s2cid=31284535|url=https://zenodo.org/record/1258545}}</ref>
* Presence of the Milky Way<ref name=Weaver/>
* Presence of the Milky Way<ref name=Weaver/>


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== Conversion of measurements into other units ==
== Conversion of measurements into other units ==
Globe at Night observations identify the dimmest stars that are visible given the surrounding conditions. Assuming normal visible acuity and clear skies, it is possible to approximately convert Globe at Night naked eye limiting maximum estimates into other units:<ref>{{cite web|last=Spoelstra|first=H|title=Dark Skies Awareness: Sky Brightness Nomogram|url=http://www.darkskiesawareness.org/nomogram.php|accessdate=14 March 2012}}</ref>
Globe at Night observations identify the dimmest stars that are visible given the surrounding conditions. Assuming normal visible acuity and clear skies, it is possible to approximately convert Globe at Night naked eye limiting maximum estimates into other units:<ref>{{cite web|last=Spoelstra|first=H|title=Dark Skies Awareness: Sky Brightness Nomogram|url=http://www.darkskiesawareness.org/nomogram.php|access-date=14 March 2012|archive-date=12 November 2020|archive-url=https://web.archive.org/web/20201112014517/http://www.darkskiesawareness.org/nomogram.php|url-status=dead}}</ref>


{| class="wikitable"
{| class="wikitable"
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== History ==
== History ==
[[File:GaN Earth.jpg|thumb|Locations of Globe at Night observations from 2009-2011.]]
[[File:GaN Earth.jpg|thumb|Locations of Globe at Night observations from 2009–2011.]]


The Globe at Night project was launched as a [[NASA]] program in the United States.<ref name=ng>{{cite web|last=Fazekas|first=Andrew|title=GLOBE at Night&nbsp;– Helping to Save the Night Sky|url=http://newswatch.nationalgeographic.com/2012/01/20/globe-at-night-helping-to-save-the-night-sky/|publisher=National Geographic|accessdate=25 January 2012}}</ref> The project quickly expanded internationally, and was part of the outreach effort of the [[International Year of Astronomy]] in 2009.<ref>{{cite journal|last=Walker|first=CE|author2=Pompea SM |author3=Isbell D |title=GLOBE at Night 2.0: On the Road Toward IYA 2009|journal=Astronomical Society of the Pacific Conference Series|date=2007|volume=389|series=EPO and a Changing World: Creating Linkages and Expanding Partnerships|url=http://aspbooks.org/custom/publications/paper/389-0423.html}}</ref> The size of the project (in terms of number of observations) expanded dramatically in that year. In 2014, the project expanded to also include data obtained via the [https://play.google.com/store/apps/details?id=com.cosalux.welovestars Loss of the Night app] for [[Android (operating system)|Android]] devices, and the [https://itunes.apple.com/us/app/dsm-lite/id626796278?mt=8 Dark Sky Meter app] for [[iOS]] devices. In addition, new star charts were added to extend the standard map based campaign throughout the whole year. In 2015, as part of the [[International Year of Light]], two "International Nights of Skyglow Observation" were introduced, to encourage data submission in March and September.<ref name=IYL_blog>{{cite web|last1=Kyba|first1=Christopher|title=Help measure how the night sky is changing|url=http://light2015blog.org/2015/02/09/help-measure-how-the-night-sky-is-changing/|publisher=International Year of Light Blog|accessdate=3 March 2015}}</ref>
The Globe at Night project was launched as a [[NASA]] program in the United States.<ref name=ng>{{cite web|last=Fazekas|first=Andrew|title=GLOBE at Night&nbsp;– Helping to Save the Night Sky|url=http://newswatch.nationalgeographic.com/2012/01/20/globe-at-night-helping-to-save-the-night-sky/|archive-url=https://web.archive.org/web/20120122230055/http://newswatch.nationalgeographic.com/2012/01/20/globe-at-night-helping-to-save-the-night-sky/|url-status=dead|archive-date=January 22, 2012|publisher=National Geographic|access-date=25 January 2012}}</ref> The project quickly expanded internationally, and was part of the outreach effort of the [[International Year of Astronomy]] in 2009.<ref>{{cite journal|last=Walker|first=CE|author2=Pompea SM |author3=Isbell D |title=GLOBE at Night 2.0: On the Road Toward IYA 2009|journal=ASP Conference Series|date=2007|volume=389|series=EPO and a Changing World: Creating Linkages and Expanding Partnerships|page=423|bibcode=2008ASPC..389..423W|url=http://aspbooks.org/custom/publications/paper/389-0423.html}}</ref> The size of the project (in terms of number of observations) expanded dramatically in that year. In 2014, the project expanded to also include data obtained via the [https://play.google.com/store/apps/details?id=com.cosalux.welovestars Loss of the Night app] for [[Android (operating system)|Android]] devices, and the [https://itunes.apple.com/us/app/dsm-lite/id626796278?mt=8 Dark Sky Meter app] for [[iOS]] devices. In addition, new star charts were added to extend the standard map based campaign throughout the whole year. In 2015, as part of the [[International Year of Light]], two "International Nights of Skyglow Observation" were introduced, to encourage data submission in March and September.<ref name=IYL_blog>{{cite web|last1=Kyba|first1=Christopher|title=Help measure how the night sky is changing|url=http://light2015blog.org/2015/02/09/help-measure-how-the-night-sky-is-changing/|publisher=International Year of Light Blog|date=9 February 2015}}</ref>


The number of observations for each year are reported on the Globe at Night webpage:<ref name=gan_analyze/>
The number of observations for each year are reported on the Globe at Night webpage:<ref name=gan_analyze/>

⚫
* 2006 - 3,990 total observations
{| class="wikitable"
⚫
* 2007 - 8,490 total observations
|-
⚫
* 2008 - 6,838 total observations
! Year !! Total Observations !! Notes
⚫
* 2009 - 15,300 total observations
|-
⚫
* 2010 - 17,805 total observations
⚫
| 2006 || 3,990 ||
⚫
* 2011 - 14,249 total observations
|-
⚫
* 2012 - 16,848 total observations
⚫
| 2007 || 8,490 ||
* 2013 - 14,879 total observations
|-
* 2014 - 18,506 total observations
⚫
| 2008 || 6,838 ||
|-
⚫
| 2009 || 15,300 ||
|-
⚫
| 2010 || 17,805 ||
|-
⚫
| 2011 || 14,249 ||
|-
⚫
| 2012 || 16,848 ||
|-
| 2013 || 16,342 ||
|-
| 2014 || 20,910 || Started including data from Loss of the Night & Dark Sky Meter Apps.
|-
| 2015 || 23,041 ||
|-
| 2016 || 14,507 ||
|-
| 2017 || 15,382 ||
|-
| 2018 || 8,069 ||
|-
| 2019 || 10,198 ||
|-
| 2020 || 29,508 ||
|-
| 2021 || 25,558 ||
|-
| 2022 || 19,950 ||
|}



== Spinoff research ==
== Spinoff research ==
Data from the Globe at Night program has also been used in a study of the effects of artificial lighting on the foraging habits of bats.<ref>{{cite journal|last=Barringer|first=D|author2=Walker, C. E. |author3=Pompea, S. M. |author4=Sparks, R. T. |title=Astronomy Meets the Environmental Sciences: Using GLOBE at Night Data|journal=Earth and Space Science: Making Connections in Education and Public Outreach|volume=433|pages=373|url=http://www.aspbooks.org/a/volumes/article_details/?paper_id=33149|accessdate=15 March 2012}}</ref>
Data from the Globe at Night program has also been used in a study of the effects of artificial lighting on the foraging habits of bats.<ref>{{cite journal|last=Barringer|first=D|author2=Walker, C. E. |author3=Pompea, S. M. |author4=Sparks, R. T. |title=Astronomy Meets the Environmental Sciences: Using GLOBE at Night Data|journal=Earth and Space Science: Making Connections in Education and Public Outreach|year=2011|volume=433|pages=373|bibcode=2011ASPC..443..373B|url=http://www.aspbooks.org/a/volumes/article_details/?paper_id=33149|access-date=15 March 2012}}</ref>


== See also ==
== See also ==
* [[Bortle Dark-Sky Scale]]
* [[Bortle Dark-Sky Scale]]
* [[Connie Walker]]
* [[Connie Walker (astronomer)]]
* [[Earth Hour]]
* [[Earth Hour]]
* [[Ecological light pollution]]
* [[Ecological light pollution]]
* [[History of street lighting in the United States]]
* [[History of street lighting in the United States]]
* [[International Dark Sky Association]]
* [[International Dark Sky Association]]
* [[List of astronomical societies]]


== References ==
== References ==
Line 98: Line 155:


== External links ==
== External links ==
* {{official website|http://www.globeatnight.org/}}
* {{Official Website|https://www.globeatnight.org/}}
* [http://www.darksky.org/ International Dark-Sky Association]
* [http://www.darksky.org/ International Dark-Sky Association]
* [http://www.darkskiesawareness.org/nomogram.php Conversion of NELM into other units]
* [http://www.darkskiesawareness.org/nomogram.php Conversion of NELM into other units] {{Webarchive|url=https://web.archive.org/web/20201112014517/http://www.darkskiesawareness.org/nomogram.php |date=2020-11-12 }}

{{Portal bar|Society|Astronomy|Stars|Spaceflight|Outer space|Solar System|Education|Science}}


[[Category:Astronomy organizations]]
[[Category:Astronomy organizations]]
⚫
[[Category:Light pollution|+]]
[[Category:Citizen science]]
[[Category:Citizen science]]
⚫
[[Category:Light pollution]]
[[Category:Meteorology and climate education]]
[[Category:Meteorology and climate education]]
[[Category:Observational astronomy]]
[[Category:Observational astronomy]]

Latest revision as of 20:08, 16 July 2024

Globe at Night
Artificial lights showing the locations of light pollution in October 2012.
Artificial lights showing the locations of light pollution in October 2012.
KeywordsLight Pollution, Astronomy, Scotobiology, Citizen Science, Crowdsourcing
Funding agencyNational Science Foundation via NOIRLab
ObjectiveMeasuring and raising awareness of artificial light pollution
Project coordinatorAURA, Connie Walker
PartnersInternational Dark-Sky Association, CADIAS
Duration2006 –
WebsiteOfficial website Edit this at Wikidata

Globe at Night is an international scientific research program that crowdsources measurements of light pollution in the night sky. At set time periods within each year, the project asks people to count the number of stars that they can see from their location and report it to the project's website. The coordinating researchers compile this information to produce a public, freely available map of global light pollution. By September 2011, almost 70,000 measurements had been made.[1] The use of data collected by the public makes the program an example of citizen science.[2] Globe at Night began as a NASA educational program in the US organized by the NOAO, and was expanded internationally during the 2009 International Year of Astronomy;[3] it is an offshoot of the GLOBE Program, which focuses on school-based science education.

Scientific rationale

[edit]
Artificial lights attract many insects, to the advantage of some spiders, as on this lighted bridge over the Loire River, France. These changes in behavior can then affect food webs and cause further knock-on effects.

Light pollution, the introduction of artificial light into formerly dark ecosystems, has numerous adverse ecological effects. Exposure to artificial light can prove fatal for some organisms (e.g. moths that fly into a burning flame), can interrupt a life cycle phase for others (e.g. glowworms are unable to attract mates), and can reduce the possibilities for finding food (because of increased risk of predation).[4] Light at night can also interfere with the chronobiology of many animals, including humans, through suppression of melatonin secretion.[5]

There are also cultural and economic reasons for concern about excessive light at night. Skyglow prevents large fractions of the Earth's population from viewing the Milky Way,[6] which drove the development of much of ancient science, mythology, and religion. In the US, the cost of generating wasted light is estimated to be 7 billion US dollars per year;[7] the production of the electricity for this wasted light also results in the release of chemical pollution and greenhouse gases.

The Globe at Night project has two main goals: raise public awareness of light pollution and its effects, and provide global mapping data for light pollution.[1][8][9]

Method

[edit]
The visibility of the constellation Orion varies depending on the observer's local level of light pollution; clear sky is on left, light-polluted sky is on right. Note that the photo at left shows more detail than can be seen with the human eye.

The project asks members of the public to go outside on dark moonless nights and report how many stars are visible in particular constellations.[1][3] The project focuses on students, teachers, and families, and has produced activity packets in 13 languages.[3][10] NASA encourages students in its INSPIRE program to participate.[11]

Participating individuals are asked to go outside on specified dates at least an hour after sunset, then let their eyes adjust to the ambient light level, and observe a specific constellation: Orion or Leo in the Northern Hemisphere, Crux in the Southern Hemisphere.[8][10][12] The choice of a two-week span of dates near the new moon removes any effect on sky brightness from scattered moonlight, and observing well after sunset prevents any lingering light from twilight.[13] By comparing the stars they see with star charts showing stellar visibility under different light pollution conditions, they qualitatively measure light pollution.[14][15] Stellar visibility can also be measured for the project using a Sky Quality Meter, a tool used by amateur astronomers.[14] These light pollution data are then submitted to the coordinating website via a web browser.[16][17] The assembled data are provided to researchers and the public via a mapping interface that displays the data overlaid on Google Maps.[18]

With this technique, observers are reporting a naked eye limiting magnitude (NELM) between 1 and 7. Humans are able to observe stars below 7th magnitude, although this may require blocking out other sources of light.[13] Under clear, unpolluted skies, the measurement of NELM should be strongly correlated with the level of light pollution. Other factors, particularly those that reduce the seeing, can reduce NELM:[13]

Globe at Night also distributes teaching kits that demonstrate how fully shielded lights reduce glare and improve the visibility of the night sky.[3][25]

Accuracy of measurements

[edit]
When Globe at Night observations are averaged together, they are very strongly related to the sky brightness in the location. This is a single panel from this image.

The standard deviation of an individual Globe at Night observation is approximately 1.2 stellar magnitudes.[2] Due to the law of large numbers, when the observations are considered in aggregate, the errors from individual observations cancel each other out, leading to very stable mean values. This means that Globe at Night observations could be used to estimate global or regional trends in sky luminance.[2]

Conversion of measurements into other units

[edit]

Globe at Night observations identify the dimmest stars that are visible given the surrounding conditions. Assuming normal visible acuity and clear skies, it is possible to approximately convert Globe at Night naked eye limiting maximum estimates into other units:[26]

NELM Visible stars mcd/m2 mag/arcsec2
1 10 160 14.6
2 30 60 15.6
3 80 20 16.6
4 250 8 17.8
5 800 3 19.0
6 2,500 0.8 20.4
7 7,000 0.2 22.0

History

[edit]
Locations of Globe at Night observations from 2009–2011.

The Globe at Night project was launched as a NASA program in the United States.[1] The project quickly expanded internationally, and was part of the outreach effort of the International Year of Astronomy in 2009.[27] The size of the project (in terms of number of observations) expanded dramatically in that year. In 2014, the project expanded to also include data obtained via the Loss of the Night app for Android devices, and the Dark Sky Meter app for iOS devices. In addition, new star charts were added to extend the standard map based campaign throughout the whole year. In 2015, as part of the International Year of Light, two "International Nights of Skyglow Observation" were introduced, to encourage data submission in March and September.[28]

The number of observations for each year are reported on the Globe at Night webpage:[9]

Year Total Observations Notes
2006 3,990
2007 8,490
2008 6,838
2009 15,300
2010 17,805
2011 14,249
2012 16,848
2013 16,342
2014 20,910 Started including data from Loss of the Night & Dark Sky Meter Apps.
2015 23,041
2016 14,507
2017 15,382
2018 8,069
2019 10,198
2020 29,508
2021 25,558
2022 19,950


Spinoff research

[edit]

Data from the Globe at Night program has also been used in a study of the effects of artificial lighting on the foraging habits of bats.[29]

See also

[edit]

References

[edit]
  1. ^ a b c d Fazekas, Andrew. "GLOBE at Night – Helping to Save the Night Sky". National Geographic. Archived from the original on January 22, 2012. Retrieved 25 January 2012.
  2. ^ a b c Kyba, Christopher C. M.; Wagner, Janna M.; Kuechly, Helga U.; Walker, Constance E.; Elvidge, Christopher D.; Falchi, Fabio; Ruhtz, Thomas; Fischer, Jürgen; Hölker, Franz (16 May 2013). "Citizen Science Provides Valuable Data for Monitoring Global Night Sky Luminance". Scientific Reports. 3: 1835. Bibcode:2013NatSR...3E1835K. doi:10.1038/srep01835. PMC 3655480. PMID 23677222.
  3. ^ a b c d Walker, Constance; Stephen Pompea (3 November 2010). "Global campaign to save energy and fight light pollution". SPIE Newsroom. doi:10.1117/2.1201009.003213.
  4. ^ Rich, Catherine and Longcore, Travis (2006). Ecological consequences of artificial night lighting. Island Press. ISBN 978-1-55963-128-0.{{cite book}}: CS1 maint: multiple names: authors list (link)
  5. ^ Navara, KJ; Nelson (2007). "The dark side of light at night: physiological, epidemiological, and ecological consequences". J Pineal Res. 43 (3): 215–224. doi:10.1111/j.1600-079X.2007.00473.x. PMID 17803517.
  6. ^ Cinzano, P.; Falchi, F.; Elvidge, C. D. (2001). "The first world atlas of the artificial night sky brightness". Mon. Not. R. Astron. Soc. 328 (3): 689–707. arXiv:astro-ph/0108052. Bibcode:2001MNRAS.328..689C. doi:10.1046/j.1365-8711.2001.04882.x. S2CID 15365532.
  7. ^ Gallaway, Terrel; Olsen, Reed N.; Mitchell, David M. (2010). "The economics of global light pollution". Ecological Economics. 69 (3): 658–665. doi:10.1016/j.ecolecon.2009.10.003.
  8. ^ a b "Globe at Night - Home page". Globe at Night. Retrieved 14 March 2012.
  9. ^ a b "Globe at Night - Analyze". Globe at Night. Retrieved 14 March 2012.
  10. ^ a b "Globe at Night Family Activity Packet". Globe at Night. Archived from the original on 3 November 2013. Retrieved 14 March 2012.
  11. ^ "EINSPIRE Communication". Archived from the original on 2013-07-06. Retrieved 2013-04-29.
  12. ^ NASA Education Office. "Join the Worldwide Globe at Night 2012 Campaign". spaceref.com. Retrieved 15 March 2012.[permanent dead link‍]
  13. ^ a b c d Weaver, Harold F. (1947). "The Visibility of Stars Without Optical Aid". Publications of the Astronomical Society of the Pacific. 59 (350): 232. Bibcode:1947PASP...59..232W. doi:10.1086/125956.
  14. ^ a b Beatty, Kelly. "Make the Effort for "Globe at Night"". Sky & Telescope. Archived from the original on 2 February 2013. Retrieved 25 January 2012.
  15. ^ "Globe at Night - Magnitude Charts Orion 40 deg N". Globe at Night. Retrieved 14 March 2012.
  16. ^ "NSF Current Newsletter - March 2012". National Science Foundation. Archived from the original on 10 March 2012. Retrieved 15 March 2012.
  17. ^ "Globe at Night webapp". Globe at Night. Retrieved 14 March 2012.
  18. ^ "Globe at Night Interactive Map viewer". Globe at Night. Retrieved 14 March 2012.
  19. ^ Kyba, Christopher C. M.; Ruhtz, Thomas; Fischer, Jürgen; Hölker, Franz (2011). "Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems". PLOS ONE. 6 (3): e17307. Bibcode:2011PLoSO...617307K. doi:10.1371/journal.pone.0017307. PMC 3047560. PMID 21399694.
  20. ^ Garstang, R. H. (October 1991). "Dust and light pollution". Publications of the Astronomical Society of the Pacific. 103: 1109–1116. Bibcode:1991PASP..103.1109G. doi:10.1086/132933. S2CID 121416771.
  21. ^ Westheimer, G (1 January 1965). "Visual Acuity". Annual Review of Psychology. 16 (1): 359–380. doi:10.1146/annurev.ps.16.020165.002043. PMID 14268891.
  22. ^ Broadfoot, A. Lyle; Kendall, Kenneth R. (1 January 1968). "The Airglow Spectrum, 3100-10,000 A". Journal of Geophysical Research. 73 (1): 426–428. Bibcode:1968JGR....73..426B. doi:10.1029/JA073i001p00426.
  23. ^ James, J. F.; Mukai, T.; Watanabe, T.; Ishiguro, M.; Nakamura, R. (1997). "The morphology and brightness of the zodiacal light and gegenschein". Monthly Notices of the Royal Astronomical Society. 288 (4): 1022–1026. Bibcode:1997MNRAS.288.1022J. doi:10.1093/mnras/288.4.1022.
  24. ^ Gittings, Neil S.; Fozard, James L. (1986). "Age related changes in visual acuity". Experimental Gerontology. 21 (4–5): 423–433. doi:10.1016/0531-5565(86)90047-1. PMID 3493168. S2CID 31284535.
  25. ^ Walker, CE; Pompea SM; Sparks RT (2010). "Dark Skies From the Ground Up: Before, During and After Globe at Night". ASP Conference Series. Earth and Space Science: Making Connections in Education and Public Outreach. 433.
  26. ^ Spoelstra, H. "Dark Skies Awareness: Sky Brightness Nomogram". Archived from the original on 12 November 2020. Retrieved 14 March 2012.
  27. ^ Walker, CE; Pompea SM; Isbell D (2007). "GLOBE at Night 2.0: On the Road Toward IYA 2009". ASP Conference Series. EPO and a Changing World: Creating Linkages and Expanding Partnerships. 389: 423. Bibcode:2008ASPC..389..423W.
  28. ^ Kyba, Christopher (9 February 2015). "Help measure how the night sky is changing". International Year of Light Blog.
  29. ^ Barringer, D; Walker, C. E.; Pompea, S. M.; Sparks, R. T. (2011). "Astronomy Meets the Environmental Sciences: Using GLOBE at Night Data". Earth and Space Science: Making Connections in Education and Public Outreach. 433: 373. Bibcode:2011ASPC..443..373B. Retrieved 15 March 2012.
[edit]
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