Globe at Night

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Globe at Night
City Lights 2012 - Flat map crop.jpg
Artificial lights showing the locations of light pollution in October 2012.
Keywords Light Pollution, Astronomy, Scotobiology, Citizen Science, Crowdsourcing
Funding agency National Science Foundation via NOIRLab
ObjectiveMeasuring and raising awareness of artificial light pollution
Project coordinator AURA, Connie Walker
Partners International Dark-Sky Association, CADIAS
Duration2006 –
Website Official website OOjs UI icon edit-ltr-progressive.svg

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.

Contents

Scientific rationale

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. Pont-canal de Briare Lamiot Pollution lumineuse4.jpg
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

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. Light pollution It's not pretty.jpg
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

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. Relationship between naked eye limiting magnitude and predicted sky luminance.png
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

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
11016014.6
2306015.6
3802016.6
4250817.8
5800319.0
62,5000.820.4
77,0000.222.0

History

Locations of Globe at Night observations from 2009-2011. GaN Earth.jpg
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]

YearTotal ObservationsNotes
20063,990
20078,490
20086,838
200915,300
201017,805
201114,249
201216,848
201316,342
201420,910Started including data from Loss of the Night & Dark Sky Meter Apps.
201523,041
201614,507
201715,382
20188,069
201910,198
202029,508
202125,558
202219,950


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. [29]

See also

Related Research Articles

<span class="mw-page-title-main">Light pollution</span> Excess artificial light in an environment

Light pollution is the presence of any unwanted, inappropriate, or excessive artificial lighting. In a descriptive sense, the term light pollution refers to the effects of any poorly implemented lighting sources, during the day or night. Light pollution can be understood not only as a phenomenon resulting from a specific source or kind of pollution, but also as a contributor to the wider, collective impact of various sources of pollution.

<span class="mw-page-title-main">Nocturnality</span> Behavior characterized by activity during the night and sleeping during the day

Nocturnality is a behavior in some non-human animals characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite.

<span class="mw-page-title-main">Sky</span>

The sky is an unobstructed view upward from the surface of the Earth. It includes the atmosphere and outer space. It may also be considered a place between the ground and outer space, thus distinct from outer space.

<span class="mw-page-title-main">Horologium (constellation)</span> Constellation in the southern celestial hemisphere

Horologium is a constellation of six stars faintly visible in the southern celestial hemisphere. It was first described by the French astronomer Nicolas-Louis de Lacaille in 1756 and visualized by him as a clock with a pendulum and a second hand. In 1922 the constellation was redefined by the International Astronomical Union (IAU) as a region of the celestial sphere containing Lacaille's stars, and has since been an IAU designated constellation. Horologium's associated region is wholly visible to observers south of 23°N.

<span class="mw-page-title-main">Observable universe</span> All of space observable from the Earth at the present

The observable universe is a ball-shaped region of the universe consisting of all matter that can be observed from Earth or its space-based telescopes and exploratory probes at the present time; the electromagnetic radiation from these objects has had time to reach the Solar System and Earth since the beginning of the cosmological expansion. Initially, it was estimated that there may be 2 trillion galaxies in the observable universe. That number was reduced in 2021 to several hundred billion based on data from New Horizons. Assuming the universe is isotropic, the distance to the edge of the observable universe is roughly the same in every direction. That is, the observable universe is a spherical region centered on the observer. Every location in the universe has its own observable universe, which may or may not overlap with the one centered on Earth.

Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnifying, light-collecting optical instrument, such as a telescope or microscope, or eye protection.

<span class="mw-page-title-main">Skyglow</span> Diffuse luminance of the night sky

Skyglow is the diffuse luminance of the night sky, apart from discrete light sources such as the Moon and visible individual stars. It is a commonly noticed aspect of light pollution. While usually referring to luminance arising from artificial lighting, skyglow may also involve any scattered light seen at night, including natural ones like starlight, zodiacal light, and airglow.

<span class="mw-page-title-main">Limiting magnitude</span> Faintest item observable by an instrument

In astronomy, limiting magnitude is the faintest apparent magnitude of a celestial body that is detectable or detected by a given instrument.

<span class="mw-page-title-main">Satellite flare</span> Visual phenomenon caused by satellites

Satellite flare, also known as satellite glint, is a satellite pass visible to the naked eye as a brief, bright "flare". It is caused by the reflection toward the Earth below of sunlight incident on satellite surfaces such as solar panels and antennas. Streaks from satellite flare are a form of light pollution that can negatively affect ground-based astronomy, stargazing, and indigenous people.

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 electric lighting on the environment, improving the well-being, health and safety of people and wildlife, and cutting down on energy usage. Earth Hour and National Dark-Sky Week are two examples of such efforts.

<span class="mw-page-title-main">Visible-light astronomy</span> Encompasses a wide variety of astronomical observation via telescopes

Visible-light astronomy encompasses a wide variety of astronomical observation via telescopes that are sensitive in the range of visible light. Visible-light astronomy is part of optical astronomy, and differs from astronomies based on invisible types of light in the electromagnetic radiation spectrum, such as radio waves, infrared waves, ultraviolet waves, X-ray waves and gamma-ray waves. Visible light ranges from 380 to 750 nanometers in wavelength.

<span class="mw-page-title-main">Warner and Swasey Observatory</span> Observatory

The Warner and Swasey Observatory is the astronomical observatory of Case Western Reserve University. Named after Worcester R. Warner and Ambrose Swasey, who built it at the beginning of the 20th century, it was initially located on Taylor Road in East Cleveland, Ohio, USA. The observatory, which at that time housed a 9.5-inch (24 cm) refractor, was donated in 1919 to the Case School of Applied Science. The newer 24-inch (61 cm) Burrell Schmidt telescope was built in 1939.

<span class="mw-page-title-main">Pan-STARRS</span> Multi-telescope astronomical survey

The Panoramic Survey Telescope and Rapid Response System located at Haleakala Observatory, Hawaii, US, consists of astronomical cameras, telescopes and a computing facility that is surveying the sky for moving or variable objects on a continual basis, and also producing accurate astrometry and photometry of already-detected objects. In January 2019 the second Pan-STARRS data release was announced. At 1.6 petabytes, it is the largest volume of astronomical data ever released.

Scotobiology is the study of biology as directly and specifically affected by darkness, as opposed to photobiology, which describes the biological effects of light.

<span class="mw-page-title-main">Bortle scale</span> Scale for measuring the brightness of the night sky

The Bortle dark-sky scale is a nine-level numeric scale that measures the night sky's brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution. Amateur astronomer John E. Bortle created the scale and published it in the February 2001 edition of Sky & Telescope magazine to help skywatchers evaluate the darkness of an observing site, and secondarily, to compare the darkness of observing sites.

<span class="mw-page-title-main">Ecological light pollution</span>

Ecological light pollution is the effect of artificial light on individual organisms and on the structure of ecosystems as a whole.

<span class="mw-page-title-main">Sky quality meter</span> Instrument used to measure the luminance of the night sky

A sky quality meter (SQM) is an instrument used to measure the luminance of the night sky. It is used, typically by amateur astronomers, to quantify the skyglow aspect of light pollution and uses units of "magnitudes per square arcsecond" favored by astronomers. SQM measurements can be submitted to a database on the manufacturer's website and to the citizen science project GLOBE at Night.

<span class="mw-page-title-main">Technosignature</span> Property that provides scientific evidence for the presence of technology

Technosignature or technomarker is any measurable property or effect that provides scientific evidence of past or present technology. Technosignatures are analogous to biosignatures, which signal the presence of life, whether intelligent or not. Some authors prefer to exclude radio transmissions from the definition, but such restrictive usage is not widespread. Jill Tarter has proposed that the search for extraterrestrial intelligence (SETI) be renamed "the search for technosignatures". Various types of technosignatures, such as radiation leakage from megascale astroengineering installations such as Dyson spheres, the light from an extraterrestrial ecumenopolis, or Shkadov thrusters with the power to alter the orbits of stars around the Galactic Center, may be detectable with hypertelescopes. Some examples of technosignatures are described in Paul Davies's 2010 book The Eerie Silence, although the terms "technosignature" and "technomarker" do not appear in the book.

The spectral G-Index is a variable that was developed to quantify the amount of short wavelength light in a visible light source relative to its visible emission. The smaller the G-index, the more blue, violet, or ultraviolet light a lamp emits relative to its total output. It is used in order to select outdoor lamps that minimize skyglow and ecological light pollution. The G-index was originally proposed by David Galadí Enríquez, an astrophysicist at Calar Alto Observatory.

<span class="mw-page-title-main">Light pollution in Hawaii</span>

Light pollution is the presence of unwanted artificial light that brightens the night sky. Improperly shielded lights are the source of many of the issues regarding the light pollution in Hawai'i. Urban centers in the cities are often so bathed in light that over a hundred kilometers from the city's edge, the light pollution resulting from the glow is present. Fabio Falchi is quoted as stating that “light pollution is one of the most pervasive forms of environmental alteration” due to its destructive nature in both un- and protected areas such as national parks. Dark night skies are an important natural, cultural, scientific, educational, and economic resource for Hawai‘i.

References

  1. 1 2 3 4 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. 1 2 3 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. 1 2 3 4 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. 1 2 "Globe at Night - Home page". Globe at Night. Retrieved 14 March 2012.
  9. 1 2 "Globe at Night - Analyze". Globe at Night. Retrieved 14 March 2012.
  10. 1 2 "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. 1 2 3 4 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. 1 2 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.
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