It is a November evening in 1572. The Danish nobleman and astronomer Tycho Brahe is returning to his uncle’s house. As he notes that the clearer sky bodes well for resuming his observations after dinner, a strange, brilliant star suddenly catches his attention. In amazement, he watches it for some time, then:

When I had satisfied myself that no star of that kind had ever shone forth before, I was led into such perplexity by the unbelievability of the thing that I began to doubt the faith of my own eyes, and so, turning to the servants who were accompanying me, I asked them whether they too could see a certain extremely bright star when I pointed out the place directly overhead. They immediately replied with one voice that they saw it completely and that it was extremely bright. But despite their affirmation, still being doubtful on account of the novelty of the thing, I enquired of some country people who by chance were travelling past in carriages whether they could see a certain star in the height. Indeed these people shouted out that they saw that huge star, which had never been noticed so high up.

Tycho Brahe’s vivid account of his response on first seeing the supernova of 1572 leaves no doubt that it impressed him. Of course Tycho Brahe had no idea he was seeing a star blowing itself to bits; it is only in the last 50 years that astronomers have recognized supernovae as a distinct class of astronomical beast and figured out what lies behind the spectacle.

Tycho Brahe’s supernova jolted European astronomy, then at a critical stage. The bolder spirits were considering the heliocentric system of Copernicus (1473-1543) as a possible alternative to the geocentric system of Aristotle (384-322 B.C.), which had been the Middle Ages’ system of choice and was still the generally-accepted scheme. The supernova certainly was not on Aristotle’s program, which held that the eighth sphere—the abode of the fixed stars—was immutable, nor did Copernicus say anything about stars popping seemingly out of nowhere. Hence Tycho Brahe’s amazement.

In a modest 180 pages. Science and Objectivity describes similar astronomical incidents of shattered expectations and broken prejudices. But, unlike Tycho Brahe and his supernova, in these cases the astronomers had no trouble seeing what was there. On the contrary, the mental baggage they brought with them to the telescope caused them to “see” more than what was actually there, and, sometimes, they continued to “see” again and again what was only in their imagination. The astronomical misadventures chronicled range from 1609 to the 1920’s. They concern what various astronomers thought they saw or, in the more recent instances, thought they measured.

One of the most interesting episodes involved Percival Lowell and the planet Mars. After graduating from Harvard in 1876, doing the grand tour of Europe, and then making some successful business investments, Lowell had the leisure to write books and indulge his keen interest in astronomy. He became particularly interested in Mars and its possibilities as an abode of an alien civilization. An Italian astronomer claimed to have observed dark straight markings on the Martian surface which he called “canali.” Translated into English as “canals,” in the English-speaking world the term had gained unintended overtones of artificial rather than natural origin. With the help of his excellent eyesight and an observatory he had built at a favorable high-altitude location in northern Arizona, Lowell took a close look at Mars. Sure enough, he saw canals; not just one or two, but a whole system of them radiating outwards from points. He concluded that Mars was inhabited and that the points were oases replenished by a planet-wide system of canals. Publication of his claim in The Atlantic Monthly and the eloquence of his pen led to a widespread late-Victorian belief in an advanced, and perhaps dying, Martian civilization.

Most other astronomers saw no sign of the canals. Lowell’s observations were attributed to his expectations and a psychological tendency of the mind to connect real points with imaginary lines when the eye is working at the limit of its resolution.

Because professional astronomers did not accept Lowell as a colleague, their public criticism of him was sometimes scathing. But, as Hetherington shows, professional astronomer status was no guarantee against illusion. A professional astronomer, Adriaan van Maanen, was at the center of an extended saga that ran through the 1910’s and 1920’s. Soon after he had measured rotation in the so-called spiral nebulae, it became apparent that these objects must be giant spiral galaxies quite separate from, and well beyond, our own galaxy. The new perspective transformed van Maanen’s measurements; initially unremarkable, they became controversial. (The spiral galaxies do indeed rotate, but so slowly—the rotation periods are hundreds of millions of years—as to be completely imperceptible to van Maanen.) Those who thought the spiral nebulae were part of our own galaxy pointed to van Maanen’s results. Those who thought they were separate systems suspected that whatever it was that van Maanen was measuring it could not be real, yet professional courtesy forbade them from saying so in print. As further evidence from other quarters accumulated, van Maanen’s position became untenable, but he did not back down. Eventually his claims slipped quietly into oblivion.

Hetherington puts these episodes in a larger context, maintaining that “science, the search for objectivity, has become the religion of the twentieth century.” No doubt about this; insofar as the West’s intellectual and cultural elites have a religion, it is indeed science, although, paradoxically, they tend to be scientifically illiterate; the word “algebra” makes them nervous and the word “calculus” makes their minds go blank. The scientist has a strong positive stereotype. He is Mr. Straight—careful, modest, shy of publicity, naively idealistic, and above all, objective. With his episodes from astronomical history as ammunition, Hetherington blows the stereotype to smithereens. Scientists are human beings, and as such they are no more, and no less, objective than auto workers.

Although the scientific stereotype is bogus, some scientists find it very useful for political purposes. The main article in the February 7, 1988 issue of Parade magazine—a section in many Sunday newspapers—featured astronomer and popularizer of science Carl Sagan on the danger of worldwide nuclear war. A preamble, which promised that readers “may find some of Carl Sagan’s insights uncomfortable and even provocative,” invited the supposition that his powerful scientific intellect and objectivity granted him insights denied to ordinary people. He divulged insights such as: “The nuclear arms race, jointly pioneered by the United States and the Soviet Union. . . . ” or “we [the US and the USSR] share a stated belief in the right of the people to rule themselves. Our systems of government were born in historic revolution against injustice, despotism, incompetence and superstition.” After an examination of the record, he was unable to find any significant difference between American democracy and Soviet totalitarianism. In short, he offered moral equivalence, “scientifically” packaged and finished with a pretty, “objective” bow.

Evidently, destruction of the “objective scientist” stereotype is an urgent matter. But this book will not change things much. Inadequate explanations of some of the episodes’ contexts will leave most readers who are not astronomers in the dark as to what is going on, and long stretches of passive, awkward, scientific journal English will put them to sleep. Unfortunately, it will take much more than this to rip off Professor Sagan’s mask of objectivity. Jocelyn Tomkin is on the staff of the astronomy department at the University of Texas.


[Science and Objectivity: Episodes in the History of Astronomy, by Norriss S. Hetherington (Ames: Iowa State University Press) 180 pp., $24.95]