Copernican heliocentrism

“ The diffusion of the Copernican opinions in the world did not take place rapidly at first. Indeed, it was necessarily some time before the progress of observation and of theoretical mechanics gave the heliocentric doctrine that superiority in argument, which now makes us wonder that men should have hesitated when it was presented to them. Yet there were some speculators of this kind, who were attracted at once by the enlarged views of the universe which it opened to them. Among these was the unfortunate Giordano Bruno of Nola, who was burnt as a heretic at Rome in 1600. ”

“ It must be remembered that in those days the doctrine of Copernicus, declaring that the sun, and not the earth, was the centre of the system, that the earth revolved on its axis once a day, and that it described a mighty circle round the sun once a year, had only recently been promulgated. This new view of the scheme of nature had been encountered with the most furious opposition. It may possibly have been that Galileo himself had not felt quite confident in the soundness of the Copernican theory, prior to the discovery of the satellites of Jupiter. ”

“ Fig. 20.—The Copernican System.
Copernicus dealt only with the six planets then known and the sun and moon. As to the stars, he had no idea that they were suns like our own, at immense and various distances from us. The knowledge of the magnitude of the sidereal [Pg 206] universe was reserved for our own century, when it was discovered by the method of parallaxes. ”

“ Furthermore the earth is not moved by water, much less by the motion of air or fire in the way we have stated the heavens are moved by the revolutions of the enveloping heavens. Copernicus further does not claim that all the heavens are immobile but that some are moved, that is, the moon, Mercury. Venus, Mars, Jupiter and Saturn. But why such diversity? No one in his senses, or imbued with the slightest knowledge of physics, will ever think that the earth, heavy and unwieldy from its own weight and mass, staggers up and down around its own center and that of the sun ”

“ That a planet's orbit is an ellipse and not the perfect circle was of course a triumph for the new science over the scholastics and Aristotelians. But they had yet to learn what held the planets in their courses.
From Kepler's student days under Mæstlin when as the subject of his disputation he upheld the Copernican theory, to his death in 1630, he was a staunch supporter of the new teaching. ”

“ The sun's claims to such a situation are satisfied through having two satellites of its own, Venus and Mercury. Copernicus's scheme is inconvenient; it overloads the earth with a triple motion; it creates a difficulty by separating the sun from the number of the planets with which it has much in common; and the "introduction of so much immobility into nature ... and making the moon revolve around the earth in an epicycle, and some other assumptions of his are the speculations of one who cares not what fictions he introduces into nature, provided his calculations answer." ”

“ The effect which the discovery had upon the reception of the Copernican system was immediately very considerable. It showed that the real universe was very different from that which ancient philosophers had imagined, 278 and suggested at once the thought that it contained mechanism more various and more vast than had yet been conjectured. And when the system of the planet Jupiter thus offered to the bodily eye a model or image of the solar system according to the views of Copernicus, it supported the belief of such an arrangement of the planets, by an analogy all but irresistible. ”

“ The Copernican system, so long as it was not purged of the artificial appendage of epicycles by the laws of Kepler, was not very much simpler than the Tychonic, and, mathematically speaking, the only difference between them was, that the one placed the origin of co-ordinates in the sun (or rather in the centre of the earth's orbit) , the other in the earth. ”

“ Could we but view this familiar constellation from a different position in space, we should perhaps be quite unable to recognise it. Mountain masses, for instance, when seen from new directions, are often unrecognisable.
It took, as we have seen, a very long time for men to acknowledge the immense distances of the stars from our earth. Their seeming unchangeableness of position was, as we have seen, largely responsible for the idea that the earth was immovable in space. It is a wonder that the Copernican system ever gained the day in the face of this apparent fixity of the stars. ”

“ In order to suppress the Copernican doctrine, it would be necessary not only to prohibit the book of Copernicus and the writings of authors who agree with him, but to interdict the whole science of astronomy, and even to forbid men to look at the sky lest they might see Mars and Venus at very varying distances from the earth, and discover Venus at one time crescent, at another time round, or make other observations irreconcilable with the Ptolemaic system. ”

“ Now it was much to discover, as Heraclides did, that the earth rotates about its own axis and that Mercury and Venus revolve round the sun like satellites; and it seems a priori incredible that one man should not only have reached, and improved upon, the hypothesis of Tycho Brahe but should also have suggested the Copernican hypothesis. ”

“ But Copernicus, in order to uphold his own hypothesis, claims the earth has three motions, its diurnal and annual ones, and trepidation; if we add to these the pull of weight towards the center, we are attributing four natural motions to one and the same body. If this is granted, then the very foundations of physics must fall into ruins; for all are agreed upon this, that each natural body has but one motion of its own, and that all others are said to be either violent or voluntary. ”

“ He gave open adherence to the Copernican system in 1610, when he constructed a telescope and discovered the satellites of Jupiter; and after this there followed discovery after discovery, like the spots on the sun and the phases of Venus, which latter discovery confirmed the Copernican hypothesis. He invented the hydrostatic balance, the proportional compass, the thermoscope, microscope, and telescope. His two most noteworthy writings are The Dialogue concerning the Two Most Important World-Systems, and Investigations into Two New Sciences. ”

“ It is easy to see why the apparent motions of the planets were accounted for by deferents and epicycles, before the Copernican system revealed the true nature of the solar system as heliocentric and not geocentric. ”

“ By the same right we might conclude that the main principles of the Copernican system cannot be immutable, because they would [pg 160] hinder the progress of science. Progress certainly does not consist in throwing away all certainty acquired, in order to begin anew. Or does it really belong to progress in astronomy to again give up Copernicus, to go back to Ptolemy and let the sun and all the stars revolve again around the earth? ”

“ The influence of the church, coupled with man’s inclination to exalt his own importance, strongly tended against the acceptance of such heterodox views. Among the many hostile critics of the [4] Copernican system, Tycho Brahe (1546–1601) stands out pre-eminently. This conscientious observer bitterly assailed Copernicus for his suggestion that the earth moved, and developed a scheme of his own which postulated that the planets revolved around the sun, and planets and sun in turn revolved around the earth. ”

“ The Copernican system once admitted, however, this difficulty of conception, at least, is effectually got over, and it becomes a mere problem of geometry and calculation to determine, from the observed places of a planet, its real orbit about the sun, and the other circumstances of its motion. This Kepler accomplished for the orbit of Mars, which he ascertained to be an ellipse having the sun in one of its foci; and the same law, being extended by inductive268 analogy to all the planets, was found to be verified in the case of each. ”

“ Then he adds that "the greatness of Copernicus has never been sufficiently appreciated nor will it be,—that man who accomplished what no astronomer before him had scarcely been able even to suggest without an insane machinery of spheres, for by a-83- triple motion of the earth he abolished epicycles and eccentrics. ”

“ The Copernican theory proving that our world is not, as was long believed, the centre of the universe, but a single planet moving with many others around a central sun, and the discovery, by the instrumentality of [Pg 199] the telescope, of the infinitesimally small place which our globe occupies in the universe, altered men's measure of probability and affected widely, though indirectly, their theological beliefs. ”

“ Johannes Kepler (1671–1630) was a native of Würtemberg and imbibed Copernican principles while at the University of Tübingen. His pursuit of science was repeatedly interrupted by war, religious persecution, pecuniary embarrassments, frequent changes of residence, and family troubles. In 1600 he became for one year assistant to the Danish astronomer, Tycho Brahe, in the observatory near Prague. The relation between the two great astronomers was not always of an agreeable character. Kepler's publications are voluminous. ”

“ in such things we ought to THINK WITH THE LEARNED, AND SPEAK WITH THE VULGAR. They who to demonstration are convinced of the truth of the Copernican system do nevertheless say "the sun rises," "the sun sets," or "comes to the meridian"; ”

“ Darwin's hypothesis is not, so far as I am aware, inconsistent with any known biological fact; on the contrary, if admitted, the facts of Development, of Comparative Anatomy, of Geographical Distribution, and of Palæontology, become connected together, and exhibit a meaning such as they never possessed before; and I, for one, am fully convinced that if not precisely true, that hypothesis is as near an approximation to the truth as, for example, the Copernican hypothesis was to the true theory of the planetary motions. ”

“ When Copernicus, the Polish astronomer, sought to extricate astronomy from the hopeless complexity into which it had become entangled by cycles, epicycles, and eccentric positions, and proclaimed the heliocentric system, his opponents objected that the earth's axis, produced to the celestial sphere, with its successive positions day after day parallel to each other, should be seen to describe a circle in the heavens as the earth sweeps round through its orbit of nearly 600,000,000 miles in length. ”

“ For in every department of science the great truths which dawn upon the mind are usually attended with a cloud of difficulties, and, but for the habit in question, they would soon be permitted to fade away, and be lost in their original obscurity. Copernicus has, therefore, been justly applauded,219 not only for conceiving, but for firmly grasping the heliocentric theory of the world, notwithstanding the many formidable objections which it had to encounter in his own mind. ”