A long time ago, I travelled to the outskirts of Amsterdam and walked into the magnificent office of Professor Petra van Dam, Dutch environmental historian extraordinaire. Petra had recently agreed to join my dissertation committee, and now I had arrived to receive instruction on the environmental history of the Low Countries. After Petra had, with typical generosity, overwhelmed me with references and ideas, she made a surprising offer. Could I come to her home over the weekend, she asked, to kayak on the water around Leiden?

Of course, I agreed. I took it as an invitation to connect with someone who would clearly play a major role in my professional life. Yet when I arrived on the banks of the water near Petra’s home – and let me tell you, there is no better icebreaker than wearing the wetsuit of your committee member’s husband – it dawned on me that Petra’s invitation represented something more: something integral to the practice of environmental history. As we glided through the water, Petra explained the landscape: its history, its human footprint, its ecology. And as we narrowly avoided boat and swan alike, I gathered something more: a feel for a place that would loom large in the dissertation I planned to write.

Since then, I have often asked myself: should environmental historians actually encounter the places – or rather, the remnants of the places – they imbue with agency in their work? What did that day on the water really mean for me?

The answer, perhaps, is that some things must be experienced to be internalized. I grew up around the Great Lakes, where water is always in mind, if not quite in sight. But the overwhelming significance of water in the coastal regions of the Netherlands was altogether new to me. Seeing it firsthand helped inspire me to write something rarely considered before: a maritime history of climate change. It also gave me a visceral appreciation for the importance of what Petra calls the “amphibious” economic, military, and cultural practices of the Dutch, from their early modern heyday to the present.

Since completing my dissertation and turning it into a book – The Frigid Golden Age, now out in hardcover – I’ve started to write about more extreme environments. I am now knee-deep in a second book: Civilization and the Cosmos, an environmental history of the solar system. In the book, I argue that sudden and profound environmental changes across the solar system have influenced cultures, altered economies, and provoked political upheaval on Earth. I trace how scientists, engineers, and military officers have recently started to alter environments in outer space, and I uncover plans for more profound transformations that are now leaving the drawing board. I show, in other words, that the solar system has been a dynamic actor in human history, shaping and increasingly shaped by ideas and institutions in societies the world over.

Given my experiences around Leiden, the book presents a problem for me. I must grudgingly admit that it seems unlikely that NASA or SpaceX will ask me to join a mission to Mars, and unlikelier still that my family or university will give me leave to go. So, at the start of my project, I wondered: would there be any way for me to encounter the environments I planned to write about? And if not, would that matter?

The answer gradually dawned on me as I finished writing the first full chapter of my new book. In it, I investigate the history of Mars observation, from the days of the Galileo and Kepler to the early twentieth century. Much of the chapter deals with what I imagine to be a dialogue between the atmospheres of Earth and Mars. I show that, beginning in the seventeenth century, local weather and small-scale atmospheric turbulence on Earth – occasionally shaped by the causes or consequences of climate change – either prevented or distorted observations of Mars. In the nineteenth century, astronomers coped, in part, by adopting the practices and language of explorers then advancing the frontiers of European empires. Astronomer-explorers sought out remote environments where the atmosphere was thin, dry, and stable.

Yet with better views of Mars, astronomers misinterpreted the Aeolian mechanics that create enormous dust storms on Mars. When these storms abruptly altered the shape of dark regions on Mars, most astronomers supposed that water must be to blame. It seemed that Mars had dynamic oceans and clouds, which meant that it could surely harbor complex life. Eventually, a large contingent of amateur and professional astronomers used telescopes of unprecedented power to detect what surely had to be the cause for these changes: enormous canals, built by what could only be an alien intelligence. As the emissaries of empire constructed enormous canals on Earth, and a series of severe El Niño events triggered catastrophic droughts across imperial possessions, astronomers supposed that Martians had used canals to cling to life on a world that was older and therefore drier than others.

As you might imagine, this “discovery” provoked tremendous popular excitement. Wealthy patrons financed new observatories to scour the surface of Mars, enthusiasts struggled to send messages to the canal-builders, military officers listened for signals, and authors captured the imagination of the public by imagining the Martians. For a few decades, much of humanity had, for all intents and purposes, encountered an alien civilization. The “canal controversy” faded slowly, and only really died when spacecraft returned their first images of an apparently lifeless Martian surface.

As I wrote this strange history, I repeatedly asked myself: what did nineteenth- and early twentieth-century observers really see on Mars? Was Mars a blank – okay, red – slate to them, one on which they projected fantasies tinged by imperial encounters with environments on Earth? Or could they see enough of the Martian environment to really make out the delicate features that appear in contemporary Mars maps? And just how big of a role did Earth’s atmosphere play in their observations?

For much of the nineteenth century, Mars observers relied on surprisingly humble telescopes. In fact, many insisted that relatively small telescopes afforded better views of planets, since their lenses and mirrors would have to look through a smaller slice of Earth’s atmosphere. Many of the telescopes used by the foremost Mars observers of the time would be outpaced by the kind of instrument you could easily buy on Amazon for less than the price of a new laptop. I eventually realized that I could buy a telescope that would let me catch a glimpse of the places and environments my nineteenth-century astronomers had made out. In a sense, I could glide along the canals of Mars, as I had once paddled through the waterways of Leiden.

None other than Percival Lowell – perhaps the leading proponent of Martian canals – wrote that “the telescope lets us traverse what otherwise had been barred, and lands us at last above the shores we went forth to seek.”

So, I bought a telescope, one I assumed would be roughly on par with the instrument used by Giovanni Schiaparell in 1877 to first discern “channels” – later mistranslated as “canals” – on Mars. Then, to get a sense of what early nineteenth-century astronomers might have seen, I also bought a smaller telescope. This one was similar to the instrument Wolff Beer and Johann Heinrich Mädler used in 1830 to argue that dark patches on Mars might be permanent features.

When I first caught a glimpse of Mars through these telescopes, it was roughly six months from its “opposition:” when Earth is directly between Mars and the Sun. An opposition happens every two years, because Mars takes that long to complete one orbit around the Sun (which means that a Martian year is almost exactly two Earth years long). The first thing that struck me was just how small Mars looked through my eyepieces. I understood, from my research, that Mars observers would wait until the months and weeks just before and after oppositions to conduct their research, which imposed a biannual cycle on their discoveries. It was easy to see why.

As Mars approached Earth and gradually ballooned in my field of view, I began to grasp – in a way I had not before – just how much agency our atmosphere has in astronomical observations. Some nights, Mars would shudder and boil in my eyepiece; others, it would stay relatively still. I understood that temperature differences in Earth’s atmosphere create unstable convection cells from our planet’s surface to a height of roughly seven kilometers. I knew that differences in the density of these cells alter their refractive index, redirecting light arriving from space and distorting the view through a telescope.

Yet it was still another thing to experience the effect firsthand. I learned to wait for fleeting moments of clarity, when our atmosphere would settle down just long enough, on the right nights, to let Mars suddenly come into focus. I could start to imagine the frustration my observers must have felt, and the temptation they must have experienced to sketch features on Mars that they could not, in fact, clearly make out. Yet I was also surprised when my humblest telescope let me glimpse dark patches on Mars that my nineteenth-century astronomers must have made out, as well. And I learned to see these darker areas more regularly: I learned, in other words, to train my eye. I gained an appreciation for the craft of my historical subjects that I had not internalized before.

Those are lessons I learned back in 2016. This year – this week, in fact! – Mars reaches “perihelic opposition,” when its orbit brings it nearest the Sun and nearest the Earth at the same time. In such oppositions, Mars is especially close to Earth. They happen just once every 15 years or so, and this imposed yet another, bigger cycle on early observations of Mars. Major discoveries – real or imagined – repeatedly happened in the year of perihelic oppositions. Beginning in 1892, journalists established close ties with well-placed astronomers to encourage public excitement about what might be discerned on the precise day of a perihelic opposition. Such oppositions quickly became popular sensations that promised new perspectives on an alien civilization.

There was, however, a problem: astronomers’ logbooks and now, spacecraft observations reveal that huge dust storms most often break out across the southern hemisphere of Mars precisely when the planet makes its closest approach to the Sun. In other words, perihelic oppositions – which offer the best views of Mars from Earth – often coincide with dust storms that obscure much of the Martian surface.

How did Martian dust storms have agency in the popular and scientific events that perihelic oppositions came to be? This year, I hoped to find out. And to my good fortune, an enormous dust storm broke out on Mars just a few months ago.

Once again, I hauled out my telescopes. Mars did indeed seem bigger than it looked in 2016, when the planet was not quite as close to Earth. Since I now understood just how subtle and fleeting surface details on Mars often appear to be from Earth, I immediately grasped why early astronomers would eagerly anticipate perihelic oppositions. Yet now, with the dust storm shrouding Mars, I actually made out less of its surface than I had in 2016. This month, I may have glimpsed the planet’s northern polar cap; I may even have caught a hint of something dark, once or twice. Yet there was little else for me to see.

Suddenly, I grasped why canal enthusiasts repeatedly argued that water on Mars really started flowing only several months after a perihelic opposition. Some have argued that enthusiasts made this claim because when Mars neared Earth, its surface was easier to see, and more obviously bereft of canals. In fact, I figured, dust storms may well have obscured the Martian surface during many perihelic oppositions, and only unveiled dark patches that could be mistaken for canals as Mars retreated from the Sun, and Earth passed it by. The environment of Mars, I reasoned, had even more agency in my story than I had supposed.

So, back to that question that stuck with me after my paddling in Leiden. Should environmental historians find some way to experience the environments they study, even when those environments are too extreme to easily visit? I increasingly believe they should. Such experiences do not always yield tangible results – although they have for me, while observing Mars – yet they do inspire impressions that can, at the very least, change the focus of our work.

Of course, if such experiences are important, we are left with a familiar problem in academia. How can we ensure that scholars who lack the privilege enjoyed by professors at major institutions still gain the benefit of experiencing the environments they study? Funding agencies, after all, are unlikely to look kindly at a request to experience an environment, merely for its own sake. Collectively, we may need to think of establishing funds in our major organizations for travel not merely to archives, but to places. Even if the means of travel is a beam of light, and the places are far beyond Earth.

Suggested reading on Mars in Culture, Science, and Society:

K. Maria D. Lane, Geographies of Mars: Seeing and Knowing the Red Planet. Chicago: University of Chicago Press, 2010.

Jason N. Dittmer, “Colonialism and Place Creation in Mars Pathfinder Media Coverage.” Geographical Review 97:1 (2007): 112.

Robert Markley, Dying Planet: Mars in Science and the Imagination. Durham: Duke University Press, 2005.

Lisa Messeri, “Extra-terra incognita: Martian maps in the digital age.” Social Studies of Science 47:1 (2017): 75-94.

Joshua Nall, “Constructing Canals on Mars: Event Astronomy and the Transmission of International Telegraphic News.” Isis 108: 2 (2017): 284.

Janet Vertesi, Seeing Like a Rover: How Robots, Teams, and Images Craft Knowledge of Mars. Chicago: University of Chicago Press, 2014.

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Dagomar Degroot

Dagomar Degroot is an associate professor of environmental history at Georgetown University in Washington, D. C. He is the founder and co-director of HistoricalClimatology.com and the Tipping Points Project, the co-director and co-founder of the Climate History Network, and the co-host of the podcast Climate History.

Latest posts by Dagomar Degroot (see all)

• Writing About Climate Change, Whaling, and Conflict in the Seventeenth Century Arctic - August 30, 2022
• Climate History, the History of Science, and the Climate Crisis - September 16, 2021
• From the Canals of the Netherlands to the Canals of Mars: Experiencing Environmental History - July 31, 2018
• Teaching Climate History in a Warming World - January 11, 2016
• New Climate History Podcast - August 6, 2015
• Towards a Climate History of the Solar System - April 2, 2015
• How Should We Measure Climate Change? What the Past Can Tell Us - October 20, 2014
• The Culture of Climate Change - August 1, 2014
• Does climate change cause social crisis? - March 26, 2014
• Reconstructing the Future: Understanding Toronto’s Wild Weather of 2013 - January 16, 2014