This is the seventh post in our Urban and Environmental Dialogues series, published in collaboration with The Metropole.
Figure 1: “Featured image (at top): Sorrento Italy at night, Ryan Reft, photographer, September 2025.”From https://themetropole.blog/2025/10/02/uha-niche-collaborative-call-for-papers-urban-and-environmental-dialogues/ (accessed October 17, 2025).
Ryan Reft’s recent photograph, “Sorrento Italy at night” (Figure 1), opened the Network in Canadian History and Environment and Urban History Association Call for Papers on “Urban and Environmental Dialogues,” of which this essay is one contribution. What was Reft seeking to highlight in this photo? I don’t know, but I can’t help reading it through the lens of my own research.
Technically more dusk than night, dark green trees, Mediterranean-style mansions, and a vivid turquoise pool dominate the foreground, punctuated by a dozen lamps. Across the sea, a city appears in the distance, barely above the horizon, the urban landscape differentiated from the similar azure hues of the Mediterranean, mountains, and sky by artificial light at night.1
Once I began studying the history of nocturnal artificial illumination and how scientists came to understand it as light pollution, I started noticing the phenomenon, even though it had been, in many ways, in plain sight.2 I began perceiving it around me as I walked, drove, and flew after sunset. It cropped up in scientific papers, newspaper articles (often covering those papers), and both historical and contemporary photographs, like Reft’s.
One of the most significant, yet underappreciated environmental transformations associated with cities since the late nineteenth century is that of the night sky, and of night itself. In this essay, I argue that nightscape is both a useful and important analytic category for environmental as well as urban historians. 3 Both fields should pay more attention to urban nightscapes and their histories.4
Environmental and urban historians have long traced the development of technological systems in cities. Some early work in these fields, and at their nexus, examined the establishment and “modernization” of water, sewer, transportation, and electrical networks.5 As my sagging bookshelves show, these scholars, along with historians of technology, also considered the emergence of urban lighting.6 Some explored how people wrestled with various forms of pollution in urban areas.7 At times, technological systems aimed to reduce pollutants, but they could also generate new scales and forms of pollution. However, few scholars working in these and allied fields have examined light pollution.8
“In this essay, I argue that nightscape is both a useful and important analytic category for environmental as well as urban historians.”
Anthropogenic illumination results in “skyglow,” the artificial brightening of the night sky as light scatters in the atmosphere and returns to Earth—that orange, hazy glow above urban horizons after dusk.9 Given dense human populations and the normalization of lighting infrastructure in many cities, skyglow has become both more extensive and more intensive since the late nineteenth century. Its growth has accelerated even more quickly since World War II and the global urbanization of the late twentieth century.10
Astronomers were the first scientists to raise concerns about nocturnal illumination. Many observatories had been built in or near city centers before extensive artificial light at night. But as artificial illumination, air pollution, and vibrations from new transit systems, like streetcars, increased in urban areas, many of these observatories closed, the buildings repurposed for non-observational work, and new scientific facilities constructed in more distant locales in an attempt to escape the problematic new qualities of urban nightscapes.11 Such was the pattern at Mexico’s Observatorio Astronómico Nacional, which was founded in Mexico City, moved to Chapultepec Castle and then Tacubaya, and later built new observatories in Tonantzintla and the Baja California peninsula—four moves between 1867 and 1969.
In 1973, UCLA astronomer Kurt W. Riegel published “Light Pollution: Outdoor Lighting Is a Growing Threat to Astronomy” in Science.12 It was the first time the term “light pollution” appeared in the influential journal.13 Science’s editors picked that issue’s cover image based on Riegel’s article. The original caption reads: “View of Pasadena and Los Angeles taken from Mount Wilson in 1911 (top) and 1965 (bottom)” (Figures 2 and 3).14
While researching my forthcoming book, Transforming Night, I had seen the journal cover many times but had never stopped to look at the photographs in detail or learn where they came from. Archived at The Huntington, photographer Ferdinand Ellerman (1869–1940) snapped the top image, described as “Night view of Pasadena lights from Mount Wilson”—home to Mount Wilson Observatory—on May 20, 1911, six years after the first telescope was installed there and three years after the world’s then-largest operational telescope was completed in 1908.15 It’s not apparent, but like so many contemporary photos that have been cropped, filtered, and otherwise modified, the image is actually a composite. Ellerman superimposed gauzy clouds from another photo above the grid of artificial light below. The identity of the other photographer is unknown, but the photo described as “Night view of Pasadena as seen from Mount Wilson” was taken in October 1965. Five decades later, the grid has become a vivid sea of illumination reaching toward the Pacific Ocean and advancing to the north and south. Whereas the urban nightscape is a luminous hint on the horizon in Reft’s contemporary photograph, artificial light is front and center in these pictures.
One of the things that strikes me about The Huntington’s description of the second photograph is that it does not explicitly mention light. The earlier “Night view of Pasadena lights” has become simply “Night view of Pasadena.” The omission could simply reflect the perspectives of two different archivists or work completed by busy archival staff. Or was nocturnal illumination in southern California by the 1960s so normal, so banal, that it went unremarked in the second description?16 Was night already becoming synonymous with artificial light?
Whoever designed the Science cover was thinking like a historian.17 The quality of the black and white photographs is mediocre at best, and reproducing them in Science degraded them further. Still, juxtaposing the nightscapes of greater Los Angeles in 1911 and 1965 powerfully visualized change over time—dare I say, changes in the night.18
“Still, juxtaposing the nightscapes of greater Los Angeles in 1911 and 1965 powerfully visualized change over time—dare I say, changes in the night.”
Skyglow has become both bigger and brighter since Riegel’s time, let alone since 1911. Dense cities like Hong Kong are now bathed in anthropogenic light from sunset to sunrise, with human and nonhuman residents experiencing what scientists call continual “artificial twilight”—a radiant hinterland where inhabitants do not experience the defining characteristic of night: darkness, though natural night skies are rarely entirely dark.19 The 2019 photograph of Hong Kong’s harbor at night—or, “night”?—reveals another aspect of artificial light’s history and its implications for urban nightscapes: shifting hues associated with changing lighting technologies, including the rapid adoption of LEDs, largely driven by the climate crisis (Figure 4).20
Some scientists studying nocturnal artificial light seek to quantify changes in nightscapes at various scales, from individual cities to the national, continental, and global.21 Using data collected by citizen scientists, researchers recently estimated that annual growth rates in what they call “night-sky brightness”—the visual perception of the nocturnal sky and how it scatters and diffuses light, whether natural or artificial—due specifically to anthropogenic illumination, have increased from three to six percent during the second half of the twentieth century, to almost ten percent between 2011 and 2022.22 Moreover, artificial light affects not only cities, suburbs, and industrial zones, but also rural remote regions. Scientists believe that, cumulatively, non-urban populations now experience 75 percent of all skyglow worldwide.23 Nocturnal illumination, then, is transforming not just urban nightscapes but those globally.
Yet nighttime light does not simply “impact” skies, cities, and their residents. As I got deeper into my research, I was fascinated to learn that diverse environmental features and phenomena—from clouds and snow to geologic formations and tree species—shape how “artificial” light actually appears in the world.24 I’ve seen this happen in my local nightscape of Ithaca, New York. In winter, snow and ice magnify artificial illumination. The lighting hasn’t changed; the environment in which that illumination is located has. Such environmental factors therefore also shape the knowledge scientists produce about nocturnal light. Conclusions drawn from data gathered in winter are not necessarily applicable to summer (and vice versa). But as that photograph of Hong Kong demonstrates, lighting technologies can also change. After a recent LED retrofit, I could perceive a notable difference in the color of skyglow above Ithaca. Tracking broad patterns in urban lighting and its effects on nightscapes like these is, well, illuminating (sorry/not sorry). Yet it obscures how artificial light is unevenly distributed within cities. Scholars analyzing lighting and demographic patterns in the United States have shown how higher levels of illumination are located in disproportionately poor, Black, and brown neighborhoods. Lighting levels are almost 2.5 times higher in communities with the most marginalized groups, when compared to the most privileged communities.25 Based on current knowledge, medical and scientific researchers believe that anthropogenic light at night is detrimental to human health.26 Marginalized communities also have fewer opportunities to experience natural darkness.27 In short, light pollution is yet another form of environmental injustice.
“In short, light pollution is yet another form of environmental injustice.”
Nocturnal skies, nightscapes, and ultimately night in cities reveal connections between land and sky, terrestrial activities and atmospheric qualities. They, too, have histories.28 Shifting urban nightscapes are therefore another domain of large-scale anthropogenic environmental change, one that is particularly significant given a global urban majority.29 Thinking with nightscape draws attention to these connections, histories, and changes, especially in this age of the Anthropocene.
Notes
1 I don’t know if Sorrento is the city in the photograph’s foreground or background, but Naples is opposite it.
2 Science journalist Ed Yong is particularly sensitive to the ways that understandings of “human” senses are often ableist. See Ed Yong, Immense World: An Immense World: How Animal Senses Reveal the Hidden Realms Around Us (Random House, 2022). On nocturnal anthropogenic light through a disability studies lens, see Antonella Radicchi and Dietrich Henckel, “Planning Artificial Light at Night for Pedestrian Visual Diversity in Public Spaces,” Sustainability 15, no. 2 (2023): 1488.
3 To date, “nightscape” is not a significant analytic tool in the humanities and interpretive social sciences. Exceptions include Ute Hasenöhrl, “Contested Nightscapes: Illuminating Colonial Bombay,” Journal of Energy History/Revue d’Histoire de l’Énergie 1, no. 2 (2019): 1d–25d; and Pamela F. Phillips, ed., Enlightened Nightscapes: Critical Essays on the Long Eighteenth-Century (Routledge, 2023). In architecture, see Aileen Hallie, “Nightscape: An Exploration of the Future for the Nocturnal Urban Landscape Design,” Master’s thesis, Delft University of Technology, February 24, 2023. The term is used in a few scientific articles, such as Ramon Alamús, Salvador Bará, Jordi Corbera, et al., “Ground-Based Hyperspectral Analysis of the Urban Nightscape,” ISPRS Journal of Photogrammetry and Remote Sensing 124 (2017): 16–26. On “electricscape,” see Diana J. Montaño, Electrifying Mexico: Technology and the Transformation of a Modern City (University of Texas Press, 2021).
4 And, ultimately, to night. Exceptions include Sara B. Pritchard, “The Trouble with Darkness: NASA’s Suomi Satellite Images of Earth at Night,” Environmental History 22, no. 2 (2017): 312–30; Dorothee Brantz, “Animals in Urban Environmental History,” in Concepts of Urban Environmental History, edited by Sebastian Haumann, Martin Knoll, and Detlev Mares, 191–202 (Transcript, 2020); and Andrew Flack, “Dark Trails: Animal Histories Beyond the Light of Day,” Environmental History 27, no. 2 (2022): 215–41.
5 Literature on the history of these systems is enormous. Influential early work includes Thomas Parke Hughes, Networks of Power: Electrification in Western Society, 1880–1930 (Johns Hopkins University Press, 1983); and Martin Melosi, The Sanitary City: Urban Infrastructure in America from Colonial Times to the Present (Johns Hopkins University Press, 2000).
6 Literature on the history of artificial illumination, including but not limited to electric light, is also vast. Select works that focus on British and US contexts include Chris Otter, The Victorian Eye: A Political History of Light and Vision in Britain, 1800–1910 (University of Chicago Press, 2008); David E. Nye, American Illuminations: Urban Lighting, 1800–1920 (MIT Press, 2018); and Jeremy Zallen, American Lucifers: The Dark History of Artificial Light, 1750–1865 (University of North Carolina Press, 2019).
7 Yet again, literature on the history of various pollutants is ginormous. An early classic is Joel A. Tarr, The Search for the Ultimate Sink: Urban Pollution in Historical Perspective (University of Akron Press, 1996). For an overview of the more recent discard studies, see Max Liboiron and Josh Lepawsky, Discard Studies: Wasting, Systems, and Power (MIT Press, 2022). For vital new perspectives on pollution, see Max Liboiron, Pollution Is Colonialism (Duke University Press, 2021).
8 One scientist has defined light pollution simply as adverse artificial light at night, due to its detrimental scientific, ecological, human health, cultural, and other effects. See John C. Barentine, public talk at ALAN conference, Calgary, August 2023. Other scientists have offered technical definitions, such as “an increased volume concentration of photons in the nocturnal environment above naturally expected values.” See Hector Linares Arroyo, Angela Abascal, Tobias Degen, et al., “Monitoring, Trends, and Impacts of Light Pollution,” Nature Reviews Earth and Environment (2024): 418. On constructing artificial light as a problem (and specifically as “light pollution”), see Taylor Stone, “Light Pollution: A Case Study in Framing an Environmental Problem,” Ethics, Policy & Environment 20, no. 3 (2017): 279–93; Samuel Challéat and Dany Lapostolle, “(Ré)concilier éclairage urbain et environnement nocturne: les enjeux d’une controverse sociotechnique,” Natures Sciences Sociétés 22, no. 4 (2014): 317–28; Josiane Meier, “Contentious Light: An Analytical Framework for Lighting Conflicts,” International Journal of Sustainable Lighting 20, no. 2 (2018): 62–77; and Sara B. Pritchard, Transforming Night: The History and Science of Light Pollution (University of Washington Press, forthcoming), chs. 1 and 2.
9 Shielded lighting (i.e., light pointed toward the ground) limits skyglow, but it doesn’t necessarily address ecological impacts on species and ecosystems.
10 Franz Hölker, Tim Moss, Barbara Griefahn, et al.,“The Dark Side of Light: A Transdisciplinary Research Agenda for Light Pollution Policy,” Ecology and Society 15, no. 4 (2010): 13; Christopher C. M. Kyba, Yiğit Öner Altitaş, Constance E. Walker, and Mark Newhouse, “Citizen Scientists Report Global Rapid Reductions in the Visibility of Stars from 2011 to 2022,” Science 379, no. 6629 (2023): 265–68; and Alejandro Sánchez de Miguel, Jonathan Bennie, Emma Rosenfeld, Simon Dzurjak, and Kevin J. Gaston, “First Estimation of Global Trends in Nocturnal Power Emissions Reveals Acceleration of Light Pollution,” Remote Sensing 13, no. 16 (2021): 3311.
11 David Aubin, “The Fading Star of the Paris Observatory in the Nineteenth Century: Astronomers’ Urban Culture of Circulation and Observation,” Osiris, 2nd ser., vol. 18 (2003): 79–100; and Randall Rosenfeld, “Technology Obscuring the Night: How Long Has Light Pollution Been Perceived as a Problem by Society Members?” Journal of the Royal Astronomical Society of Canada 116, no. 2 (2022): 65–71.
12 Kurt W. Riegel, “Light Pollution: Outdoor Lighting Is a Growing Threat to Astronomy,” Science 179, no. 4080 (1973): 1285–91.
13 Aparna Venkatesan and John C. Barentine, “Noctalgia (sky grief): Our Brightening Night Skies and Loss of Environment for Astronomy and Sky Traditions,” Science 380, no. 6650 (June 16, 2023), 1.
14 I cannot include the complete Science cover here without permission (and fees) from the journal. It is available online: https://www.science.org/toc/science/179/4080 (accessed January 9, 2026).
15 The Huntington was formerly known as The Huntington Library, Art Museum, and Botanical Gardens.
16 On “environmental generational amnesia” (a version of what is now often called “shifting baseline syndrome”), see Peter Kahn, “Children’s Affiliations with Nature: Structure, Development, and the Problem of Environmental Generational Amnesia,” in Children and Nature: Psychological, Sociocultural, and Evolutionary Investigations, edited by Peter H. Kahn Jr. and Stephen R. Kellert, 93–116 (MIT Press, 2002).
17 In his article, Riegel was thinking like a historian, too. See Pritchard, Transforming Night, ch. 2.
18Thomas W. Davies and Tim Smyth, “Why Artificial Light at Night Should Be a Focus for Global Change Research in the 21st Century,” Global Change Biology 24, no. 3 (2018): 872–82; and William Cronon, Changes in the Land: Indians, Colonists, and the Ecology of New England (Hill and Wang, 1983).
19 Lee Billings, “New Map Shows the Dark Side of Artificial Light at Night,” Scientific American, June 10, 2016.
20 Scholarship on the history of lighting technologies is considerable. For detailed histories, see Brian Bowers, Lengthening the Day: A History of Lighting Technology (Oxford University Press, 1998); and Maureen Dillon, Artificial Sunshine: A Social History of Domestic Lighting (National Trust, 2002). On some of the implications of LEDs for light pollution, see Christopher C. M. Kyba, Theres Kuester, Alejandro Sánchez de Miguel, et al., “Artificially Lit Surface of Earth at Night Increasing in Radiance and Extent,” Scientific Advances 3, no. 11 (2017): 1; Christopher C. M. Kyba, Andreas Hänel, and Franz Hölker, “Redefining Efficiency for Outdoor Lighting,” Energy and Environmental Science 6, no. 7 (2014): 1806–9; Nona Schulte-Römer, Josiane Meier, Max Söding, and Etta Dannemann, “The LED Paradox: How Light Pollution Challenges Experts to Reconsider Sustainable Lighting,” Sustainability 11, no. 21 (2019): 6160; and Joachim Schleich, Bradford Mills, and Elisabeth Dütschke, “A Brighter Future? Quantifying the Rebound Effect in Energy Efficient Lighting,” Energy Policy 72 (2014): 35–42.
22 Hölker et al., “The Dark Side”; Kyba et al., “Citizen Scientists Report,” 265–68; and de Miguel et al., “First Estimation.”
21 For an example of reducing night-sky brightness in one city, see John C. Barentine, Constance E. Walker, Miroslav Kocifajd, et al., “Skyglow Changes over Tucson, Arizona, Resulting from a Municipal LED Street Lighting Conversion,” Journal of Quantitative Spectroscopy and Radiative Transfer 212 (June 2018): 10–23. For early images at national and continental scales, with comments on the potential for global-scale imagery, see Pierantonio Cinzano, Fabio Falchi, and Christopher D. Elvidge, “The First World Atlas of the Artificial Night Sky Brightness,” Monthly Notices of the Royal Astronomical Society 328, no. 3 (2001): 689–707. On the history of tracking larger-scale changes, see Pritchard, Transforming Night, chs. 4 and 5.
23 Daniel T. C. Cox, Alejandro de Sánchez de Miguel, Jonathan Bennie, Simon A. Dzurjak, and Kevin J. Gaston, “Majority of Artificially Lit Earth Surface Associated with the Non-Urban Population,” Science of the Total Environment 841 (October 2022): 156782.
24 See Pritchard, Transforming Night, especially ch. 3 for geology, ch. 5 on trees, and ch. 7 for clouds and “snowglow.”
25 For national-level analysis, see S. M. Nadybal, T. W. Collins, and S. E. Grineski, “Light Pollution Inequities in the Continental United States: A Distributive Environmental Justice Analysis,” Environmental Research 189 (2020): 109959; Qian Xiao, Yue Lyu, Meng Zhou, et al., “Artificial Light at Night and Social Vulnerability: An Environmental Justice Analysis in the U.S., 2012–2019,” Environment International 178 (2023): 108096; and Elsa Genevieve Ingwersen, “Illuminating Inequity: An Analysis of Socioeconomic Disparity in Light Pollution Distribution by U.S. Census Tract,” Master’s thesis, Georgetown University, 2024. On “overillumination” (or “forced illumination”) and race, vital work includes Simone Browne, Dark Matters: On the Surveillance of Blackness (Duke University Press, 2015); Celeste S. Henery, “Race and the Paradoxes of the Night,” Black Perspectives, September 16, 2019; and Lauren Scorzafava, “Black History Month: A History of Forced Illumination,” DarkSky International blog, February 18, 2021.
26 For overviews, see Ron Chepesiuk, “Missing the Dark: Health Effects of Light Pollution,” Environmental Health Perspectives 117, no. 1 (2009): A20–A27; DarkSky, “Light Pollution Affects Human Health,” October 5, 2023, https://darksky.org/resources/what-is-light-pollution/effects/human-health/; and DarkSky International, Artificial Light at Night: State of the Science 2025, Zenodo, May 22, 2025, 7–9.
27 Chanda Prescod-Weinstein, “The Right to Know and Understand the Night Sky,” Medium, March 23, 2019.
28 In contrast, Charlier and Bourgeois assert that “the night sky, a timeless object, whose very nature detaches it from any danger inflicted by humans and societies, attained the status of a heritage to preserve and protect.” See Bruno Charlier and Nicolas Bourgeois, “‘Half the Park Is After Dark’—Dark Sky Parks and Reserves: New Concepts and Tools to Grant Nature Heritage Status,” L’Espace géographique (English Edition) 42, no. 3 (2013): 186–198, quotation from 191.
29 Davies and Smyth, “Why Artificial Light.” In addition, already in 2001, Cinzano et al. argued that artificial light is “one of the most rapidly increasing alterations to the natural environment.” See Cinzano et al., “The First World Atlas,” 689.
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