The Theory of Heliocentrism

Nicolaus Copernicus, Giordano Bruno, Tycho Brahe, Johannes Kepler, and Galileo Galilei were all to one extent or another hounded and harried during their lives by political and religious conflicts. All faced their deaths under less than ideal conditions, being forced to place their hope and faith in their posterity where their contemporaries had failed them. Fortunately, all of their hopes were realized. For the factors that made their lives so challenging were temporary, while the universe they studied is, if perhaps not quite eternal, at least effectively so by the standards of human timekeeping.

Kepler had guessed that it might take 100 years for the importance of his astronomical work to be recognized. In the event, it took far less than that. As early as 1631 — just one year after his death, and while Galileo still had eleven years left to live — the Rudolphine Tables proved their worth in a very public way. They predicted a “transit” of Mercury on November 7, 1631; this meant that the innermost planet would pass directly in front of the Sun as seen from the perspective of the Earth, appearing as a small black dot highlighted by the solar glow. Astronomers all over Europe pointed their instruments eagerly upward when the big day came. The Rudolphine Tables didn’t disappoint. “I have found it!” exclaimed the French astronomer Pierre Gassendi (who, like all of his colleagues, was able to look at Mercury directly only thanks to the techniques for damping down the fearsome light of the Sun that Galileo had invented). “I have seen it where no one has ever seen it before!”

As everyone rushed to compare notes and observations, no one paused for very long to consider how much harder it would have been to explain such a transit in a geocentric system. Already now, a year before Galileo would be charged as a heretic for promoting heliocentrism, more educated astronomers than not knew in their heart of hearts that it had to be the true order of things, even if they didn’t feel free to say so in mixed company.  Heliocentrism’s complete victory was thus in many ways already ensured well before Galileo was placed on trial. The Church might prevail in this last rearguard battle, but it could only lose the war. As he was making his false confession, Galileo surely knew that as well as anyone. What was the point of becoming a martyr for a cause which was the opposite of lost? To his logical mind, it just didn’t compute.

A German Protestant astronomer named Matthias Bernegger embarked on a Latin translation of Dialogue Concerning the Two Chief World Systems in order to bring it to a wider European audience. (Bernegger had been, interestingly if incidentally, a pen pal of Kepler in the last years of that man’s life.) He had it printed in Strasbourg in 1635. By then, reports of the trial of Galileo had turned heliocentrism into a cause célèbre across a broad swath of the European intellectual classes, especially in the Protestant lands, and the book now found many eager readers among them. It is possible, in other words, that all of the steps Pope Urban VIII took to repress heliocentrism may have only hastened its spread in the final reckoning, in a sort of seventeenth-century version of the Streisand Effect.

To be sure, the guilty verdict against Galileo did have a chilling effect on the discourse for a while in Catholic Europe. At about the same time that Bernegger’s translation was being published, the great French philosopher René Descartes felt compelled to purge his own positive assertions about heliocentrism from his latest book. “I would not wish, for anything in the world, to maintain them against the authority of the Church,” he wrote in a letter to a friend. “I desire to live in peace and to continue the life I have begun, under the motto ‘to live well you must live unseen.'” Descartes was presumably not the only one who decided to stay mum on a controversial and potentially dangerous topic. And yet the period of time which it remained so was of surprisingly short duration, even in the traditional bastions of the Inquisition.

When the Thirty Years War justified its name by coming to an end in 1648, it left most of the Protestant countries of Europe, and along with them their unlikely ally of Catholic France, strengthened rather than weakened. These relative winners had cottoned on that neither Protestantism nor Catholicism was going anywhere; the two branches of Christianity would have to learn to live with one another. Religiously muddled Greater Germany had a more muddled exit from the war; while the institution of the Holy Roman Empire was driven further down the long road to irrelevancy and oblivion by the manifest inability of the emperor to control his own purported citizenry, the hole his weakness opened up would be swiftly filled by the increasingly prosperous and dynamic German burgher states. The regions that came worst out of the war, on the other hand, were the Iberian and Italian Peninsulas, the places where the Catholic Church and its Inquisition had long been the strongest of all. In the era that was now dawning, the Church would have less and less ability to control the political discourse; ditto the cultural discourse on a subject like heliocentrism. The Counter-Reformation had stopped the worst of the bloodletting at the hands of Protestantism, but it could not restore the Church to its old pinnacle of ubiquity and power, even in the Catholic lands. It would soon become clear that the Galileo Affair had taken place at just about the last historical instant when such a thing could have occurred.

As heliocentrism became the conventional wisdom, so too did the new view of the celestial realm as a place no more divine or necessarily mysterious than the terrestrial one — a place where all of the same laws of physics applied, a place that human minds could study and in due course begin to comprehend. And as the notion of astronomy as just another branch of the physical sciences took hold, the ancient art of astrology lost its luster in tandem. Serious astronomers no longer had to take time out to cast the horoscopes of their friends, family, and patrons — for, while they recognized that the fates of humans might be written in the stars in some ways, those ways did not have anything to do with the ancient Zodiac.

By 1687, astrology was well on its way to becoming the parlor game most of us see it as today. That same year, the Englishman Isaac Newton used the physics of Galileo’s Two New Sciences as well as Kepler’s Third Law of Planetary Motion, both of which shouted to him that even massive bodies like the planets must be subject to comprehensible laws of motion, to help formulate his Theory of Gravity. Kepler’s 100-year window for having his achievements recognized was still only half expired when he did so.

Already by that same point, Kepler’s thoroughly literal definition of heliocentrism, which said that the Sun was the center of the entire universe, was ironically fading in prominence, to be replaced by the infinite cosmos that had first been broached by Giordano Bruno, who had neither looked all that hard at the night sky nor ever solved an astronomical equation in his life, and yet somehow had sensed the truth anyway. For that matter, Galileo too had seen and known, although his discernment in this respect remains overshadowed even today by the heliocentric aspect of his arguments. Indeed, one of the chief ironies of the Galileo Affair is that the Church authorities got so fixated on the notion of the Earth placed in a subservient position to the Sun that they never even noticed that Galileo in the very same book had dared to posit a greater cosmos vastly more threatening to their view of the divine order. In the broad strokes, it was the same theory of the cosmos for which they had burnt Bruno at the stake.

This infinite universe, with neither the Earth nor the Sun at its center,  was becoming more and more accepted among astronomers by the time Isaac Newton dropped his bombshell. For as their telescopes got better and better, they began to observe things that made it impossible to continue to imagine the stars as mere pinpricks of light on the inner surface of a heavenly sphere that enclosed the Sun and the planets like a fleet of ships in a bottle. As we have seen, already in Galileo’s time telescopes were revealing that the Milky Way was not really a wash of pure light on the inner surface of the sphere, but rather a cluster of stars that were clearly farther away than their more distinct companions in the night sky, such that they could only be discerned as individual shapes via magnification. After a new breed of reflecting telescopes came on the scene to let astronomers peer yet further, there appeared other, heretofore completely unsuspected clusters of stars. Some brightened and faded in magnitude, or even appeared and disappeared altogether, showing that these distant reaches of the heavens were no more perfect and unchanging realms of divine order than was our own solar system. Speaking of which: “solar system” was another neologism that had to be created to suit the changing times. What had once been the entire universe was reduced to just our local neighborhood.

It could only be a matter of time before the lack of stellar parallax, the first and last refuge of the geocentrists, was shown to be no lack at all, for the very reason that Archimedes had guessed at two millennia earlier: because the stars — except for our star, that is — were just too far away for parallax to make its presence known without the aid of extremely delicate instrumentation. The race was on among astronomers to invent said instrumentation and prove this assertion for a fact. In 1838, the German Friedrich Wilhelm Bessel finally did so. He took a bead on the star 61 Cygni one night, then did so again from the exact same location six months later. On this second night, he found that the star’s apparent position had slipped by .000087 degrees. From this data, Bessel concluded that 61 Cygni must be about 58 trillion miles (93 trillion kilometers, or about 10.5 light years) away. He was within 15 percent of the figure an astronomer would cite today; not bad for a first attempt. But the really important point was that stellar parallax was real, Archimedes (and Aristarchus) validated from two millennia beyond the grave.

The people who had studied the heavens between that time and this one were just people; they weren’t demigods, nor even unadulterated heroes. Certainly the five astronomers whom we have followed closely in this book were all riddled with human flaws and foibles, born of the whole disquieting range of core human weaknesses. The worst of their ideas, which were often as much the product of insecurity or arrogance as simple errors of reasoning, can make them seem downright foolish today. Copernicus had his endless epicycles within epicycles, Bruno and Kepler (and Newton) their airy-fairy mysticism, Tycho his weird hybrid of geocentrism and heliocentrism, Galileo his rigid insistence on perfectly circular orbits and his odd notions about the tides. In each of their cases, we can list a hundred ways in which they could have done their work even better. Nonetheless, each contributed where and as his humanity allowed. And in time, their bad ideas were thrown out, even as they were privileged to down in history for their good ones. This is the way this thing we call Science is supposed to function. Indeed, as Copernicus and Bruno and Tycho and Kepler and Galileo were revolutionizing our view of the universe and our place in it, they were doing much to invent modern science. The Enlightenment was waiting in the wings.

And where did all of this leave Religion, which after the further assaults on its domains unleashed by the likes of Charles Darwin would come to be seen by many as Science’s natural antagonist? In truth, it left it more or less where it had always been, left it to fill those holes in human experience where rationality feels inadequate. The Catholic Church may not have rushed to apologize for its treatment of Galileo, but nor did it rush to prosecute any more astronomers as heretics. After formally acknowledging that the Church had been in the wrong in the Galileo Affair in 1979, Pope John Paul II ordered an inquiry into the root causes of its persecution of a man who had merely stated the physical truth of the universe. The board of inquiry published its conclusions in 1992: “The majority of theologians did not perceive the formal distinction that exists between the Holy Scripture itself and its interpretations, and this led to them unduly transferring to the field of religious doctrine an issue which actually belongs to scientific research.” A secular skeptic might call this just the “God of the gaps” in new clothing, might note that every issue in scientific research was once deemed a matter for religion… until it wasn’t anymore. “The fact that the pope continues to consider himself an authority capable of saying something relevant about Galileo and his science shows that, on the pope’s side, nothing has changed,” groused the Spanish historian of science Antonio Beltrán Marí. Meanwhile the newspapers just chortled. “It’s official,” wrote The Los Angeles Times. “The Earth revolves around the Sun, even for the Vatican.”

But the fact was that that truth had long since set in, even in the Catholic Church — as had the still more unnerving one of an infinite universe, in which we are nowhere near to the center of anything. It is said that the Protestant English poet John Milton visited Galileo near the end of the latter’s life. (How amazing it would have been to be a fly on the wall at that meeting!) A quarter-century later, when Milton had gone as blind as Galileo had been at the time of his visit, he composed his epic Paradise Lost, the greatest work of religious literature between Dante and ourselves. Most of it seems to hew to geocentrism, albeit perhaps more out of reflexive habit and deference to tradition than thoughtful consideration. But then there is this, where a suspicion of the infinite, and with it its handmaidens Doubt and Fear, creeps in:

When I behold this goodly Frame, this World,
Of Heav’n and Earth consisting, and compute
Their magnitudes, this Earth a spot, a grain,
An Atom, with the Firmament compar’d
And all the numbered Stars, that seem to roll
Spaces incomprehensible (for such
Their distance argues and their swift return
Diurnal) merely to officiate light
Round this opaceous Earth, this punctual spot
One day and night; in all their vast survey
Useless besides, reasoning I oft admire
How Nature wise and frugal could commit
Such disproportions…

In reality, “nature wise and frugal” commits no such disproportions. We are poor, insignificant creatures of terrestrial clay, gazing up in awe upon a universe whose dimensions and purpose we cannot begin to understand, knowing not why we came to be here, but sensing in our bones even if we refuse to acknowledge it in our minds that the story told by our priests and pastors cannot be the whole truth of the matter. The history of astronomy can all too easily be seen as a tragic history of our own diminishment — from the favored creations of a singular God, standing in a place of privilege at the center of his universe, to ephemeral atoms adrift in an uncaring void, accidents of physics who will come and go in the blink of a cosmic eye, leaving no more collective mark upon the immensity than most of us individuals will leave upon the sadly circumscribed history of our poor mortal species. “I have seen the dark universe yawning,” wrote H.P. Lovecraft, “where the black planets roll without aim, where they roll in their horror unheeded, without knowledge, or lustre, or name.” All of us have seen — or rather felt — this yawning, nihilistic emptiness at one time or another.

But I would like to propose that there can also be peace and comfort in our cosmic insignificance. Whatever its ultimate purpose or purposelessness, we are a part of this vast something we call the universe, and in that simple statement is or ought to be a sense of belonging. We are all stardust; it is from the stars that we were born, and when the day comes for us to leave this life we will not really leave at all, but be folded back into the fabric of time and space. And during the time and space in between, we get to live within this universe of magic and wonders, on this precious little planet of ours, where every single day is bursting with the ineffable. There are still plenty of gaps left to be filled. May we all find ways to do so with gods of life, love, and beauty.

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(A full listing of print and online sources used will follow the final article in this series.)