Percival Lowell and the Canals of Mars

Matthew J. Sharps

The planet Mars has always fascinated humanity. In fact, it seems to interest us considerably more than most things in the night sky.

This makes sense; Mars is often not only clearly visible but conspicuously red like blood. So many ancient societies associated Mars with war, always of considerable interest to the human species. Mars appeals to us both as a physical object for observation and as a lure for mythological speculation.

There is a duality here. On the one hand, there is the visible planet; the red coloration reflects its geology. On the other hand, there is the Mars of interpretation, whose red color reflects its attributional warlike nature; this says a lot more about human psychology than it does about the planet Mars itself.

The red planet causes us to observe and to speculate.

Speculation. That’s where the problems come in. There is physical reality, and there is interpretation; and it is frequently the interpretation, rather than the reality, that seizes the attention of human beings. Our brains are remarkably predisposed to the interpretation of objective physical reality in psychological, self-referential terms. Unfortunately, these terms are frequently just plain wrong.

Examples of this are legion. In previous articles in SI, my coauthors and I have discussed ordinary objects that have metamorphosed, in the minds of their observers, into nonexistent phenomena ranging from UFOs to Bigfoot, and we have found specific patterns of mental processing that contribute directly to these misinterpretations (e.g., Sharps et al. 2016). In the more prosaic but more sinister worlds of eyewitness memory and officer-involved shootings, we have frequently found innocuous things such as power tools being transformed, psychologically, into far less innocuous firearms (e.g., Sharps 2017). It is very clear that our brains can lead us to see meaningful patterns where none actually exist and that we may extrapolate what we believe about a given perception to the perception itself. We tend to interpret what we see in terms of what we believe; this brings us back to the planet Mars.

Percival Lowell in 1914, observing Venus in the daytime with the 24-inch (61 cm) Alvan Clark & Sons refracting telescope at Flagstaff, Arizona.

Mars was the special focus of Percival Lowell, an important pioneer in planetary astronomy. Using his own considerable wealth, he created the great observatory at Flagstaff, Arizona. Lowell’s computations there led ultimately to Clyde Tombaugh’s discovery of Pluto, and Lowell’s financial and intellectual support led to a literally stellar progression of Lowell Observatory discoveries to the present day. Many of his observations, and those of other scientists at the Observatory, have proven startlingly accurate (e.g., Schindler 2016).

Some of his other observations, however, present problems.

One of Lowell’s most important discoveries, in his opinion, was finding canals on the surface of Mars. These long, straight, clearly artificial irrigation systems were ubiquitous. For Lowell, the dry landscape of Mars quite literally supported an intelligent race of beings with something like civil engineering degrees who were transporting water all over the place in their canals.

It wasn’t just Lowell. Schiaparelli saw canals, or at least ditches (canali). Schiaparelli’s ditches were long and straight and rectilinear, completely failing to obey the laws of perspective on the Martian planetary spheroid, but he saw and reported them anyway. Flammarion believed in canals, although he was also big on vegetation on the moon as well, so we might want to be a little careful there. Douglas, Lowell’s assistant, also saw canals—until he decided they didn’t really exist, was fired by Lowell as a result, and went on to invent dendrochronology at the University of Arizona. A lot of professional astronomers saw Martian canals, drew the things, and speculated on their nature.

But there aren’t any Martian canals.

That’s the problem: there just aren’t any damn canals on Mars. Lowell, and many other expert observers, saw them.

But they’re just not there.

The Mariner spacecraft thoroughly photographed Mars way back in 1964. Mariner found craters, rocks, flat bits and pointy bits, and bits with hills, but it didn’t find a single canal. Anywhere.

Mariner did, of course, photograph many Martian surface structures of great interest to planetary astronomers. Lowell saw many of them, half a century earlier, through his excellent telescopes. The man was no fool; some of his drawings of the Martian surface are practically identical, in broad outline, to photographs of the planet taken from the Hubble space telescope. But his canals, drawn with equal clarity, simply don’t exist.

Map of Martian “Canals” by Giovanni Schiaparelli

You might assume that continuing progress in telescope technology would have reduced the observation of these canals in the early years of the twentieth century, but you’d be wrong. I had the honor of examining a number of globes and maps of Mars, held today in the excellent archives at the Lowell Observatory; these very clearly show an increase in the number and complexity of canals as new observations were made and new globes and maps created. Canals became more numerous and elegantly geometric as the observations poured in. Some canals even doubled in perfect parallel, an astonishing phenomenon termed gemination; all of this despite the fact that there were never any real canals to begin with.

These nonexistent canals had real staying power. As mentioned earlier, the Mariner orbiter, in 1964, proved that there were no canals on Mars, but I examined a 1969 map in the Lowell archives that still showed the canals, in all their impossible rectilinear glory. The ruler-straight lines of the canals were relatively faint, as if the planetary cartographers were somewhat ashamed of these non-existent features, but these completely imaginary ditches were certainly there, in the imaginations and on the maps of scientific areographers. This was five years after Mariner had completely disproved their existence.

How do we explain this? Was Lowell, a fine observational astronomer, hallucinating? And were all the other astronomers who “saw” these bizarre ditches, straight and clear and marching over the Martian landscape, similarly afflicted with bizarre psychological disorders?

Of course not. Hallucinations derive from three sources: organic brain changes, psychosis, and extraordinary levels of stress. Lowell suffered from none of these. Granted, in the 1890s, Lowell left astronomy for four years due to a “nervous” condition, but nobody has ever suggested that he suffered from any of the conditions that produce hallucinations, and he kept seeing canals anyway. So did a lot of less nervous people; his predecessor Schiaparelli observed whole networks of Martian canali, as did a number of contemporaneous astronomers, none of whom were psychotic or brain damaged.

What on Mars was going on?

Well, that would be nothing. What was happening was not on Mars at all. The canal phenomenon was very clearly happening on Earth in the minds of the astronomers affected; for whatever reasons, a lot of them had canals on the brain.

The construction of the Panama Canal

Now, if anybody had a right to have canals on the brain, it was the aforementioned Giovanni Schiaparelli. Born a mere twenty-five miles from Canale, Italy, within thirty miles of several major transportation canals and living during a period in which the Suez and Panama Canals were the wonders of the world, it would be rather strange if Schiaparelli did not regard canals as the apotheosis of civilization, even though he himself only referred to the Martian canals as channels or ditches (canali). He may very well have had a mental set (e.g., Sharps 2017) about such things, a habitual way of looking at the world in canal-related or channel-based terms. This is of course speculation and can never really be anything more, but what we know for certain is that such habits of mind are intensely individualistic, based in our own idiosyncratic experience, and may form one of the first dynamics suggested to explain observation of the nonexistent canals of Mars: Individual Differences. Some people see canals. Others don’t.

But why does anybody see them in the first place? As mentioned, research in my laboratory, published primarily in SI (e.g., Sharps et al. 2016), has elucidated some of the psychological dynamics of those who think they see Bigfoot, flying saucers, aliens, and ghosts. One of the things we found in that research was that people generally don’t make something out of nothing. In other words, you don’t see Bigfoot on a featureless plain; you see an ape-shaped tree stump or something similar, and your brain makes Bigfoot out of it for you. The same brain-based phenomena can also create a Loch Ness monster out of a school of Scottish salmon, a Death Star out of a helicopter with a broken landing light, and so on. These Gestalt reconfigurations result from our mental misperception and misinterpretation of real things in the real world—or on the real Mars—and these phenomena are governed by specific psychological laws. These laws are suggested to be a major psychological source of the observation of the canals of Mars.

But how does an astronomer such as Lowell or Schiaparelli maintain his beliefs in these canals, to the point at which, in the face of mounting professional opposition, he sees more and more of them? Human beings are social creatures with the ability to develop strong investments in our ideas and beliefs. This is suggested to be another major source of the Canal phenomenon: sociocognitive influences, to be joined with individual differences and Gestalt reconfiguration.

Based on an intensive review of the relevant literature, and on the observations I was privileged to make in the Lowell Archives and also through Lowell’s own 24-inch Clark telescope at the great Lowell Observatory, I submit that the erroneous observations of the canals of Mars can be better understood in terms of these three sets of dynamics.

Individual Differences

The precise influences on Lowell’s thinking cannot now be ascertained. But it is clear that in 1901, when Lowell drew an “artificial planet,” a mock-up disk designed to evaluate the accuracy of observational drawings, Lowell drew not one but two parallel canals, a “gemination,” when in fact there had been “only a broad shading” in that portion of the model (Sheehan 1988). Part of Lowell’s family wealth derived from investments in the great canal systems of the eastern United States. These were regarded at the time as among the modern wonders of the world and were used extensively to ship a tremendous variety of goods, including the textiles that were a major business interest of the Lowell clan (see Hoyt 1976 and Sheehan 1988); this was yet another source of his individual affiliation with canals and their builders. In the presence of this influence, he turned a “broad shading” into two very specific, but nonexistent, canals. It might readily be suggested that Lowell, perhaps like Schiaparelli, was something of a victim of a canal-based mental set. This speculation may or may not have merit, but we do know that when Lowell, as an individual, was offered the opportunity to draw a shadow, he drew a hydraulic engineering system.

These individual differences would of course have interacted with the conditions of any given observation—but in what way? In my own work at the Lowell Observatory, I observed both Mars and Jupiter through the great Clark telescope preserved there. Now, I am an aging researcher with very thick glasses, but what I can say is that the observations danced before me very swiftly, the result of atmospheric fluctuation. Sometimes I would seem to see a feature on Mars, and then it was gone, or obscured, within two or three seconds. This type of highly variable, atmospherically based visual fluctuation would certainly have been there for Lowell and his colleagues as well. Obviously their training and experience would have rendered them vastly superior observers to me. But expertise aside, the fact is that brevity of observation limits our precision, in astronomy as in criminal eyewitness identification. Brevity can completely change our interpretation of our observations (e.g., Sharps 2017), whether we think we see a criminal suspect with a gun or a canal on the planet Mars. In short, if we have strong individual psychological reasons to see canals, we will see them if the observational conditions permit them at all. Lowell saw them, to the degree that when his assistant A.E. Douglas questioned these interpretations, he was essentially fired. Observations are subject to the psychology of the individual interpreting them; this is a crucial principle that all scientists, in all fields, should consider.

Gestalt Reconfiguration

The astronomer E.M. Antoniadi was rather caustically critical of Lowell in most respects. Although he reported the odd Martian canal himself, he demonstrated, very enthusiastically, that many of the “canals” were in fact the result of observation of a series of surface features: craters, rocks, and so on, arranged by the forces of geology into linear patterns. Lowell, and the other “canal” observers, saw discrete surface features arranged by natural forces into relatively straight lines, and joined them, perceptually, into “canals” (e.g., Sheehan 1988).

How is this possible? Gestalt psychology, the venerable theoretical perspective that deals with perceptual and cognitive configuration, provides rather good answers (e.g., King and Wertheimer 2005; Kohler 1947). Consider two of the Gestalt laws of perception, the laws of closure and of good continuation (see Sharps 1993). When we see objects that are close together, we tend to see them as connected; and when they form contours, lines, or curves, we tend to see them as units. Lowell, and the other canal believers, saw craters and rocks very close together. These astronomers, with their human nervous systems, tended to see these things as contiguous. The contours thus created frequently formed lines, hence the canals. Contours of disconnected rocks were “closed,” perceptually, into solid lines; under brief observation conditions, these lines appeared very solid, and they showed “good continuation” with other discrete features of the Martian surface. These factors would have created, perceptually, the “canals” (Sheehan 1988).

If an astronomer such as Lowell was individually predisposed to see canals and observed them with unavoidable fluctuating brevity, the Gestalt phenomena of closure and good continuation would practically ensure that he would see them, real or not (Sheehan 1988; Sharps 1993; 2017).

Sociocognitive Factors

In a letter to Lowell’s brother, Lowell’s assistant, A.E. Douglas, pointed out that the canals might have a psychological origin. Lowell discharged him.

Lowell regarded any psychological explanation for the canals as anathema. He may have seen the psychological idea as psychopathological, rather than as rooted in the normal principles of cognition and perception; whatever the source, he fired Douglas. Lowell had invested enormously, in financial and in psychological terms, in the canals of Mars, and as has been demonstrated many times, strong investment leads to strong beliefs that are difficult to sway even in the presence of contrary evidence. The principle of cognitive dissonance (Festinger 1957; Sharps 2017) deals with this rather nicely. Even if a given idea proves to be completely wrong, we tend to hold to it, and even to defend it with relatively incoherent cognitive processing, if we’re sufficiently invested in it (Festinger 1957).

Lowell had given the canals of Mars everything he had, in terms of a very long-term emotional and financial investment. The canals of Mars, in Lowell’s mind, were the greatest discovery of his own observatory. To acknowledge error would have been virtually impossible for him, in view of this investment; he never gave up on his belief in the canals, even and especially in the face of mounting pressure and criticism from his colleagues and his detractors.


The Martian surface is densely covered with features derived from the geological processes of the planet and from astronomical impacts over an enormous span of time. These surface features create a variety of irregularities that are very clear in photographs from spacecraft and from modern telescopes. However, through the telescopes of the early twentieth century, these features would have been much less readily resolved. This relative lack of resolution would have resulted in perceptual and cognitive misinterpretation with reference to the Gestalt principles cited above. This is especially true when the fluctuating brevity of optical astronomical observation is considered and when we further consider the reinforcing factors derived from individual differences and from sociocognitive factors, cementing early interpretations of those observations into a form of cognitive concrete.

It’s obviously impossible to perform experiments on the astronomers of the past. But within the realm of theoretical psychology, we can absolutely state that the observation of the canals of Mars demonstrates neither psychopathology nor incompetence on the part of pioneering scientists such as Lowell. Instead, we find an important lesson for our more modern inquiries. The scientist does not lie outside of the natural world. Rather, the scientist is entirely part of that world and is subject to scientific law; in the present case, to elements of the Gestalt laws of perception and cognition and to the laws of related areas of experimental psychology. It is important for all scientists, in all disciplines, to be aware of these essential facts and to use them to exert caution in the interpretation of what might otherwise be interpreted as purely objective observations.


I wish to thank the Lowell Observatory for allowing me to conduct research for this article in their excellent facilities. Special gratitude goes to outstanding Lowell Observatory scholars Brian Skiff, Kevin Schindler (author of the excellent book Images of America: Lowell Observatory), and most especially to Archivist Lauren Amundson, for generously sharing their time and expertise with me during my research. Thanks also to CSUF student Amanda Briley for excellent research assistance. All interpretations (and mistakes) in this article are my own and do not necessarily reflect the opinions of Lowell Observatory or of these outstanding scholars.



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