Nicolaus Copernicus (1473-1543) [See biography] studied at the University of Cracow in Poland, and at Bologna and Padua in Italy. He became a canon at Frauenberg Cathedral. During his time in Italy he was assistant to astronomer Domenico Novarra of Ferrara (1454-1504), and made astronomical observations. Copernicus was aware that measurements of the movements of the planets revealed discrepancies in the Ptolemic theory. These were usually explained away by postulating fixes called deferents and epicycles, but the accumulation of "fixes" tended to make the Ptolemaic scheme very complicated. Copernicus discovered, perhaps influenced by his reading of ancient Greek manuscripts that mentioned the heliocentric views of Aristarchius and others, that supposing the sun was the center of the planetary motions could make things much simpler. His ideas were summarized in a manuscript circulated in 1530 called the Commentariolus.
Over the next 13 years he developed his heliocentric theory, culminating in De Revolutionibus Orbium Coelestium, published in 1543. He produced clear arguments against the geocentric view of the universe. His system retained the rigid firmament of the stars, and circular movements for the planets.
[See Copernican System.]
In 1576 Thomas Digges (1546-1595) contributed a supplement containing sections of Book 1 of De Revolutionibus by Copernicus translated into English, in a posthumous edition of his father Leonard Digges's book, Prognostication euerlasting. The universe was described as extending infinitely. Thomas suggested the resulting astronomical system was more than just a mathematical hypothesis, but was "a Perfit Description of the Caelestiall Orbes." He sought to have these ideas tested by experiment and observation. Copernicus had mentioned the idea of infinite space but did not commit himself to it. His diagram of the heliocentric system showed the firmament as the sphere of the fixed stars, which he thought was large enough to account for the absence of stellar parallax.
Frances R. Johnson wrote that Thomas Digges
...clearly perceived that, the moment the rotation of the earth was conceded, there was no longer any necessity for picturing the stars as attached to a huge, rotating sphere at a definite distance from the earth... Digges had the courage to break completely with the older cosmologies by shattering the finite outer wall of the universe. He was the first modern astronomer of note to portray an infinite, heliocentric universe, with the stars scattered at varying distances throughout infinite space.
Similar views were held by Italian philosopher Giordano Bruno (1548-1600) [See biography]. Bruno was in constant conflict with traditional doctrines. His book On the Infinite Universe and Worlds, in which he argued that there are many other inhabited worlds, was published in 1584. Bruno believed that man's perception of the world is relative to the position in space and time from which he views it, and so, there are as many possible modes of viewing the world as there are possible positions. He was tried for heresy by the Inquisition in 1591, and after being imprisoned in Rome, he was burnt to death in 1600.
Digges apparently experimented with an early telescope. He as well as Tycho Brahe unsuccessfully attempted to detect parallax of a supernova which appeared in 1572. Sawyer Hogg stated:
It is one of the ironies of early science that they selected a star of the highest possible absolute magnitude, a supernova, hence the one kind of star visible to the ends of the universe, and therefore on the average having the smallest parallactic shift of any! Even with our modern instruments we could not measure a direct trigonometric parallax for this star.
Tycho Brahe (1546-1601) [See biography] devoted himself to astronomical observation after noticing a new star, a supernova, in 1572. He made observations of stars at his observatory, Uraniburg, which was financed for him by King Frederick II of Denmark. His theology did not permit him to adopt the Copernican theory, and instead he developed the theory which was part geocentric, part heliocentric. The planets revolved around the sun, but the sun and the firmament revolved around the earth.
Galileo Galilei (1564-1642) [See biography] constructed a telescope, and turned it towards the sky. He discovered four satellites of Jupiter, and interpreted them as evidence in favour of the Copernican theory. He observed sunspots, and mountains on the surface of the moon, and many new stars. He published his discoveries, creating great interest in science. He provoked controversy when he ventured to express his views on the relation between science and scripture in his Letter to the Grand Duchess Christina in 1615. The Church reacted by placing the De Revolutionibus of Copernicus on the Index of Forbidden Books in 1616. Galileo was forbidden to hold or defend the doctrine of the motion of the earth. In 1632 Galileo published his Dialogue on the Two Principal Systems of the World, which his adversaries viewed as supporting the Copernican theory. He was denounced to the Inquisition and forced to "abjure, curse and detest" his heresy concerning the motion of the earth in 1633. He was kept under surveillance at Rome till his death.
For a Catholic view, see: The Galileo Affair.
Paolo Antonio Foscarini (1565-1616) [See biography] founded of a Carmelite monastery at Montalto in Southern Italy. Foscarini was a mathematician, and a teacher of philosophy, as well as a theologian. In Naples in 1615 he published a "Letter concerning the Opinion of the Pythagoreans and Copernicus about the Mobility of the Earth and Stability of the Sun, and about the New Pythagorean System of the World", declaring the heliocentric theory to be true. It was dedicated to the General of the Carmelite Order. Foscarini then went to Rome to defend the Copernican theory against charges that it was in conflict with scripture. Christoph Clavius, leading Jesuit mathematician from 1570 to 1612, had argued against the heliocentric theory from the Bible in his astronomy textbook. Foscarini's work was placed on the Index in 1616, and he died shortly afterwards.
Johannes Kepler (1571-1630) [See biography] used the observations of Tycho Brahe to investigate the orbit of the planet Mars. His three laws of planetary motion initiated a new kind of astronomy. The first law stated that the motions of planets are not circular but elliptical with the sun at one focus. The second law stated that the straight line between the planet and the sun sweeps out equal areas in equal times. These two laws were published in Astronomia Nova in 1609. The third law, that the squares of the periods of revolution of the planets are related to one another as the cubes of the major axes of their orbits, was published in 1619 in Harmonices Mundi. Kepler doubted that planetary spheres existed. He calculated the distance of the firmament to be four million sun diameters, which was 2,000 times greater than Ptolemy's universe. Its thickness he estimated as nine English miles, which meant the stars contained in it would be quite small. Kepler supposed the masses of the firmament, the sun, and the ether were equal, and they were the three symbols of the Holy Trinity.
The development of the modern concept of universal gravitation, first proposed by Gilles de Roberval (1602-1675), the suggestion by Alphonse Borelli in 1665 that the planets would fall into the sun if they were not counterbalanced by a centrifugal effect, like a stone in a sling, the publication of Isaac Newton's Principia in 1687, and other developments eventually made the idea of a rigid, rotating heavenly firmament obsolete. But the scriptures that seemed to support this idea had to be explained. Theologians began to say that the word firmament could mean "expanse" from the concept of expanding a piece of metal by beating it flat with a hammer. The word "expanse" seemed to apply to the atmosphere, as well as to space beyond. Clouds carried water in vapor form, and so could be identified with the "waters above the firmament." The idea that the firmament could refer to the air might be derived from the statement in Genesis 1:20 that birds fly in the firmament. The identification of the firmament with the air was suggested in the writings of Augustine, as Joachim Rheticus pointed out in a tract on scripture and the motion of the earth written about the year 1543 [Hooykaas, p. 89]:
St. Augustine, in spite of the fact that the Scripture appears clearly to teach what should be understood by "firmament" in the work of the fourth day, yet has praise for him who, because of the authority of Scripture, has managed to find an interpretation about the waters above the firmament both plausible and acceptable to the senses; namely that the clouds in the air should be called waters, - which they are potentially - and the space between us and them "the firmament," since in the Scriptures the air is often called "heaven."
John Calvin's Commentary on Genesis supported this interpretation. Readers who would like to translate the Hebrew word raqia as "expanse" should be aware that for many centuries the word was understood to mean something solid. If this is ignored, the writings and beliefs of early theologians and astronomers become incomprehensible, and much of the symbolic meaning of medieval art, architecture and literature is lost. The Church's commitment to the concept of a rigid firmament in the sky was demonstrated and reinforced by the tradition of incorporating elaborate domes and arches in prominent buildings. Medieval paintings generally featured the firmament in a background arc or border, beyond which God and the angels dwelt.
In the eighteenth century Isaac Newton's theory was gradually accepted by scholars, especially in the English speaking world, in spite of initial severe criticisms from Dutch mathematician Christiaan Huygens (1629-1695) [See biography] and German philosopher Gottfried Wilhelm Leibnitz (1646-1716). [See biography]. The competing philosophy of Rene Descartes (1596-1650) [See biography], which invoked vortices of matter to account for the planetary movements, remained popular in France. In Germany, Leibnitz argued that Newton's force of gravity was an occult quality.
[See Newton's biography.]
[See also Newtonia.]
French philosopher Francios Marie Arounet, better known as Voltaire (1694-1778) [See biography], the arch enemy of intolerance in the Catholic Church, and all forms of superstition, popularized Newton's discoveries in France. Elements of Sir Isaac Newton's Philosophy, dedicated to Emilie de Breteuil, Marquise du Chastelet (1706-1749) [See biography] was an English translation of Voltaire's work. Both French and English editions were published in 1738. Voltaire thought Newton's discoveries were too important to remain in obscurity. He wrote: "Newton's Philosophy has hitherto seemed to many as unintelligible as that of the Ancients; but the darkness of the Greeks proceeded from their having in reality no light at all, while that of Newton arises from his light's being too remote from our eyes. He has discovered truths; but he has searched for, and placed them in an abyss, into which it is necessary to descend, in order to bring them out, and to place them in full light." The story of Newton contemplating the falling apple is due to Voltaire. Emilie, who was a competent mathematician, translated Newton's Principia into French. The work was published posthumously in 1759.
About this time, Mikhail Lomonosov, who had studied at Freiberg, first introduced the Copernican theory at the Academy in St. Petersburg in Russia. James Ferguson published Astronomy Explained by Sir Isaac Newton's Principles in 1756. He claimed astronomy provided strong evidence of creation, because the mechanical principles which governed the universe showed it could not be eternal. The return of a great comet in 1758 as predicted by astronomer Edmund Halley (1656-1742) [See biography] on the basis of Newton's theory gave the final confirmation to the new science. It was Halley who financed the publication of the original edition of Newton's Principia.
Musician William Herschel (1738-1822) [See biography] of Hanover migrated to England in 1757, having fled from the French occupation, and became interested in astronomy. His improved telescope and diligent observations led to the discovery of the planet Uranus in 1781. He demonstrated the sun's motion through space, and discovered over 800 multiple stars, and more than 2,500 nebulae and star clusters in his lifetime.