Scientists who espouse theories that turn out to be wrong are rarely remembered with affection by the public or by their scientific brethren. And yet this is not true of the handsome, wealthy, and wonderfully articulate Percival Lowell, scion of a Boston dynasty and the man who established an astronomical observatory in Arizona for the express purpose studying Earth's closest voyager around the sun, our planetary neighbor Mars.

It was Percival Lowell who planted the idea that the Red Planet is crisscrossed by canals deeply into American consciousness, adding later that these canals were probably made by intelligent beings. It would be hard to overstate how this fantasy gripped America at the turn of the 20th century. It spread like wildfire in newspapers, magazines, and books. The Canals of Mars became the story of the age.

Percival Lowell was a well-liked figure in 1900. To his credit, he probably did more to bring then-emerging revolutionary ideas of planetary science to public attention than other distinguished science writers of his era. He also published three highly acclaimed books in a span of a dozen years: M ars in 1895; Mars And Its Canals in 1906; and the most ambitious of all, Mars As The Abode Of Life in 1908.

We know today that there is nothing on Mars that remotely resembled engineered canals. So how and why did so many eminent men of science across America come to adopt an idea that was so wrong? How, in fact, did the Canals of Mars contradict me germinate and evolve?

This compelling and deeply mysterious story of early 20th century science took hold of me again (the first time was as a teenager in the 1960s) through the magic of the Gutenberg Project and the Internet Archive when I downloaded, on my Kindle and on my desktop , copies of Edward S. Morse, Mars And Its Mystery , (Boston: 1906), Little Brown.

The strange tale begins in the last quarter of the 19th century when weird lines on the Martian surface were reported by a reputed Italian astronomer, Giovanni Schiaparelli, who saw what appeared to be, in his own small telescope, razor-straight cuts along the surface of the planet. He termed them " canali " in his published account in 1877. The Italian word " canali " was mistranslated into English as "canals , " although " canali " actually means "channels." The distinction is crucial, for "channels" are the work of weathering and nature (or can be) while "canals" are made only by men.

Edward Morse, a dilettante astronomer himself, was a dear friend of Percival Lowell and often his houseguest in Arizona and Massachusetts. Morse is an easier read than Lowell for he is both dispassionate and reasonable. He presents both sides of every argument. Percival Lowell, though a delightful writer, was a man gripped by an idée fixe, a preoccupation held so intensely it could not be rationalized. Percival Lowell that became a zealot, and zealots too often make for tough reading, especially when their errors, years later, have been starkly and incontrovertibly revealed.

Morse tried to see the canals himself:

"I was enabled to observe Mars every night for nearly six weeks through his [Lowell's] twenty-four inch refractor," he writes, "the last and probably the best telescope ever made by [Alvan] Clark, mounted in one of the steadiest atmospheres in the world and at an altitude above sea level of over 7,000 feet.

"Imagine my surprise and chagrin when I first saw the beautiful disk of Mars through this superb telescope. "

What a wonderful phrase: "the open mouth of a crucible filled with gold." But not a single canal, or even a line resembling a canal.

It is important for non-astronomers to help how hard it is to see Mars in a telescope planted on Earth. This is not because of distance. Mars is at opposition to Earth every 780 days. If it is also at perihelion (meaning that it is closest to the Sun in its elliptical orbit), Mars is only 35 million miles away. Although this may seem far, it is a flea-jump in the vasty reaches of our solar system. The problem for astronomers was then and remains today distortions produced by our atmosphere.

When NASA's Mariner 4 took photographs of Mars in 1965 (only 49 years after Lowell's death), no canals were seen. By 1969 Mariner 6 and Mariner 7 had badly mapped all of Mars. Today, even high school students can access topographical maps of Mars that resolve every object on the planet's surface to within a few inches.

Alas for poor Percival Lowell, the verdict on the Canals of Mars controversy is in: Lowell was not merely wrong, he was spectacularly deluded . Indeed, the Canals of Mars debate was one of the most intense, misguided, and extremely wrong delusions of mainstream science.

Mars got enthusiastic coverage in the media of Lowell's era – newspapers and glossy magazines (one can only imagine how a 24/7-news cycle and popular television outlets like the History Channel would add to the hoopla). Early science fiction writers, most notably Edgar Rice Burroughs, quickly jumped aboard the 'intelligent Martians' hypothesis, creating such a wide read works as the Princess of Mars , his pulp-fiction treatment of life on the Red Planet (Burroughs had already established his reputation among others as the father of Tarzan of the Apes) .

How did this all come about? It seems to stretch all credulity.


Three significant factors were at work in the acceptance by so many legitimate people of such a wrong-headed idea as canals on Mars, to say nothing of canals on Mars built by intelligent bees.

The first was the eminence that cloaked the men who espoused the theory, especially that of their leader Percival Lowell himself, a man who looked the part of a great scientist and held all the right credentials.

The second had to do with the impressive technology Lowell used to make his canal maps. This was embodied most starkly in the magnificent (and highly photogenic!) Clark Refractor, a spectacular telescope. Images of the giant telescope featured in every newspaper account of the canals.

The third factor had to do with a phenomenon called 'seeing,' despite the most decisive factor of all. The problem of 'seeing' is still the bane of Earth-bound astronomy.

Let's start with Percival Lowell the man: Lowell's ideas were taken seriously because Percival Lowell was the most serious of men. An 1876 graduate of Harvard College (with a degree in mathematics), he gave a precocious lecture in his twenties, considered remarkably advanced at the time, on the nebular hypothesis of star formation, a theory that we know today to be absolutely correct. His professors and colleagues alike thought him brilliant, and with good reason.

To Lowell's chagrin, after Harvard his wealthy father made him run a cotton mill for five years. Later, left to his own devices and to pursue the study of Mars, Lowell created (and paid for out of his own personal fortune – Americans seem to have an odd affection for rich men who pursue scientific careers!) An astronomical observatory that to this day is considered one of the best in America. At its heart was cutting-edge technology, a telescope that allowed Lowell to magnify images of Mars by a factor of five hundred.

In the thin air of a small mountain peak, Mars Hill, at 7,200 feet above sea level near Flagstaff, Lowell built his eponymous observatory, a facility that boasted the most advanced astronomical tool of its age, the Clark Refractor, which Lowell helped to design in 1894. Constructed in 1896 by the respected engineer Alvan Clark and paid for with $ 20,000 of Lowell's money, the device was shipped by train from Massachusetts to Arizona in crates. It is still in daily use, although today mainly as an educational tool.

The Clark Refractor is a magnificent piece of scientific engineering. Its paired crystal objective lenses (the ones at the 'big' end that point to the stars) are each two feet in diameter, perfectly ground so that they are shaped to a tolerance measured in millionths of an inch. The casing of the telescope is a polished brass tube a tenth the length of a football field.

A simple way to think of the Clark Refractor is as a pirate's spy-glass, but one that is 32 feet long, weighs six tons, and has a gigantic light-gathering lens at its front two feet across! In essence, that is all there is to it, though in the details there are all sorts of add-ons, fillips, and gadgets that add to its power to gather light from far away.

The Clark, at the time of its installation, was the largest and most powerful telescope west of the Mississippi. Because it is so perfectly mounted and balanced in its settings, even though it weighs 5,400 kilograms a single human hand can easily move it. It is regarded as Alvan Clark's finest telescope.

In 1930 it was the Clark that Clyde Tombaugh used to discover the 'planet' Pluto (and the name 'Pluto' was assigned in part because the first two letters, PL, also happened to be Percival Lowell's initials). As late 1969 United States Air Force cartographers were generating highly detailed maps of our Moon using the venerable Clark. These maps were annotable to the astronauts of the Apollo program, the NASA effort that put the first humans on the Moon. The magnificent Clark looks the part of a great telescope!

So we have the personal charisma and eminence of Lowell, the jaw dropping Clark Refractor, and lastly we have the problem of 'seeing,' the issue that may be the most decisive of all in understanding the mass hallucination that infected America.

'Seeing' is a term of art astronomers use for the difficulty that they have viewing objects from Earth through a telescope. For example, an astronomer will say "the 'seeing' was excellent tonight and I got a lot of work done;" or in the alternative, "I came home early and read a book because the 'seeing' was so dreadful this evening."

The problems of 'seeing' are mainly caused by the skin of atmosphere that surrounds our planet like a gaseous ocean, its fluid nature, and the fact that gas, like glass, refracts light (that is, it bends it). Eddies and currents in the air itself, to say nothing of suspended soot, volcanic ash, and dirt, distort and cloud even nearby objects.

This distortion that occurs in 'seeing' can easily be experienced first-hand on any hot day in a parking lot: the shimmering images of cars and buildings is precisely the problem faced every night by astronomers. Changes in density of the air caused by temperature and molecular motion make the atmosphere behave just as shards of glass might do, refracting light and greatly distorting images.

Even at 7,200 feet above sea level, as at Mars Hill in Arizona, with most of our atmosphere far below him, Lowell and his teams had to deal every night with the problems of 'seeing.'


Edward Morse began his personal experiment with a clear mind and with full awareness of the pitfalls that lay before him:

"I had been somewhat prejudiced as to the existence of the canals by the comments of sporadic observers, many of what, by the way, had never been able to see them, and condemning that any one else ever had, straightway proceeded to suggest a theory to explain their presence! Careful to avoid any bias in the matter I rigidly refused to allow either Professor Lowell or his assistants to suggest where I might find a canal or a marking on the disk. "

When Morse made his first observations of Mars, as we saw earlier, far from seeing canals he was mercifully observed a cauldron of golden light. Consider also these revealing glimpses from his diary:

"May 14. Midnight. Saw planet for the first time. A beautiful luminous disk with shades of tone dimly visible.

"May 15. Certain details sufficiently distinct to make out dark areas, and at times a line or two."

Edward Morse was faithfully at the eyepiece of the mammoth Clark telescope every night for six weeks. By mid-June, his diary records a very different visual experience:

"June 12. Rather poor 'seeing' though some of the dark regions came out with remarkable distinctness. Every day I notice a very slight improvement in detecting lines.

It was not long before Morse was seeing what others reported also. We must ask ourselves if this tells us us more about human psychology and group behavior than it does about astronomy or life on other planets? Morse eventually became convinced, like Percival Lowell, that canals exist on Mars, though the word 'mystery' in the title of his book suggests that doubts may have remained.

Percival Lowell went much farther than Morse. Captivated by thousands of hours at the controls of the Clark, he made hundreds of sketches of canals, each more intricate than the last. Lowell spent the rest of his life (until his death in 1916) trying to describe them in greater and greater detail. The canals, he wrote, "run for thousands of miles in an unswerving direction, as far relatively as from London to Bombay, and as far actually as from Boston to San Francisco."

And then Lowell took an even greater leap, hypothesizing sapient creatures who must have built these great works.

And so sometimes now we have some insight into how the Canals of Mars became one of the most spectacularly wrongheaded delusions in the recent history of science. To be fair, most astronomers of the Lowell period could see no canals and many prominent astronomers represented their doubts about canals (much less intelligent Martians!) In public criticisms of Lowell's work. But Lowell's ideas had taken deep root in the public imagination. And there they stayed at least until the Second World War.

Morse himself puts it most beautifully:

"To one unconvinced of the existence of some signs of intelligent activity in Mars, the suggestions that have been made to account for certain appearances in the planet will seem absurd.

"If, on the other hand, he finds himself in agreement with those who believe the marks are the result of intelligent effort, then he is justified in using the various artificial marks of the surface of the Earth as standards of comparison in explaining the many curious marks of Mars. "

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