By Dr. Sara B. Pritchard
Department of Science & Technology Studies, Cornell University

Figure 1: Earth at Night 2012, 5 December 2012. Credit: NASA Earth Observatory.

So it began.

This was the image that sparked my interest in light pollution and light-pollution science (Figure 1). The National Aeronautics and Space Administration released new images of Earth at night, including this one, on December 5, 2012, at the annual meeting of the American Geophysical Union.

It is strangely beautiful—and disturbing. Like an insect attracted to a light (an apt metaphor, given what I am now studying), I kept coming back to the map.

For one thing, it kept popping up in the news, scientific outlets, and social media. I kept seeing and became increasingly obsessed with it. And each time, I would dive into undisciplined leads on light pollution, thanks to the miracle of The Internet.

I kept thinking, There is an important story here—about humans’ relationship with the night, about transformation of the nocturnal environment since the late nineteenth century. Later, I began to ask far nerdier questions: How do scientists study and visualize artificial light at night? How do their models of knowledge production shape what we know about light pollution?

Fast-forward a year. I was at a reception at Cornell, chatting with two colleagues. One was relatively new to the university. She asked me about my current research.

I told her I was torn. Supposedly, I was studying water management in French North Africa during the colonial and postcolonial eras, a project that flowed (sorry) from my previous research on the history of the transformation of France’s Rhône River since World War II. I had done eight weeks of research during two archival stints in France, and written an article and a conference paper that could lead to another publication, but I just couldn’t get excited about the project. I didn’t feel that I had anything new or important to say.

“But I’m obsessed with light pollution,” I confessed to her. “Perhaps I’ll jump ship and work on that.”

I proceeded to tell my colleagues about the NASA image above. Both of them had, in fact, also seen it and—for whatever reason—it was memorable enough that the map had stuck in their minds, too.

However, one colleague pointed out that most scholars in her academic tribe—critical development studies—read it quite differently. For them, like her, it was a map of lighting poverty—a lack of artificial light at night.

One image, at least two interpretations.

The idea that the NASA image could be a visualization of lighting poverty had not (yet) crossed my mind. Given dominant narratives in environmental history (one of my main fields), it made sense as a map of light pollution. Given dominant narratives within critical studies of development, it (also) made sense as a map of lighting poverty.

Same map, such different meanings.

Like NASA’s image, our conversation stuck in my mind. As I began the slow process of jumping ship—from hydraulic politics in France and the French empire to the history of light pollution and light-pollution science—I considered writing a short essay about the map and submitting it to the “Gallery” section of Environmental History. In the end, I wrote about another image, this one, City Lights of Africa, Europe, and the Middle East (Figure 2).

Figure 2: City Lights of Africa, Europe, and the Middle East, 5 December 2012. Credit: NASA Earth Observatory.

But that conversation stayed with me and it also began to shape how I read City Lights.

How, then, do we see artificial light at night—both its presence and its absence? And how should we?

Sara B. Pritchard’s new article is “ “The Trouble with Darkness: NASA’s Suomi Satellite Images of Earth at Night,” Environmental History 22 (April 2017): 312-330. She thanks Lori Leonard and Wendy Wolford for the conversation referenced here. She also thanks Shoshana Deutsh, Finis Dunaway, María Fernández, Durba Ghosh, Jenny Goldstein, TJ Hinrichs, Julie Livingston, Margot Lystra, Neil Maher, Laura Jane Martin, Rachel Prentice, Fernando Rodriguez, Marina Welker, Wendy Wolford, and graduate students in the History of Architecture at Cornell University for constructive feedback on previous drafts of the Environmental History article. Pritchard’s current research is supported by the National Science Foundation’s Program in Science, Technology, and Society (Grant No. 1555767).