Looking back at this episode with a historical lens, some analysts have wondered how the story of an irrigation-based society of intelligent Martians was ever engaged as a serious proposition. Some have been temped to discount it as an example of science gone wrong, as a hoax, or as something more related to fiction and fantasy than to science. Others have taken the Mars frenzy seriously as a culturally meaningful development, usually focusing on the powerful role some astronomers played in influencing popular interest.  These scholars have looked at astronomers’ personalities, philosophical beliefs, and social networks for clues that help explain this influence. Such works have helpfully identified religion, the theory of evolution, and the culture of science popularization as key factors that led to rampant speculation about Mars and its supposed inhabitants. [6]

Building on this, my own research has worked to put the Mars frenzy and the debates over Martian geography into the context of other intellectual and geopolitical developments that were occurring at the same time. In focusing an analytical lens on the geographical elements of the turn-of-the-century Mars debates, I argue that much of the power of astronomers’ claims actually came from the visual and iconic format in which they were most often presented – the map.  Maps served not merely as graphic repositories for astronomers’ observational data; they also presented visual arguments, sometimes unintended, for the existence and character of intelligent life on Mars.

First Maps of Mars

Starting in the mid-nineteenth century, improvements in telescope technology made it possible for astronomers to observe the planet Mars in better detail than ever before. Newly visible details, however, were not definitely known to be permanent landscape features, as some suspected they might be clouds or atmospheric phenomena similar to those on Venus and Jupiter. Given this uncertainty, observers typically used a representational convention of producing single-view sketches that showed the appearance of Mars’s disk as observed at a single place and time. This form of mapping or sketching implicitly acknowledged that different viewers might see different things, even when observing Mars at the same time. [7]

Over time, as certain details were seen by different observers to appear repeatedly in the same location on Mars’s disk, astronomers concluded that they must be viewing the visible surface of Mars, rather than a mass of swirling cloudcover. As this certainty improved, the representation of Mars evolved from the single-view sketches into composite mapping formats that used compilations of multiple observations to produce global charts of the planet.