BOOK REVIEWS || JOURNAL OF CREATION 32(1) 2018

The Copernican debate: science vs science not science vs religion

religion in their opposition to the Setting Aside All Authority: Copernican geokinetic system. Giovanni Battista Riccioli and Graney argues that it was largely a the science against Copernicus science-versus-science debate, rather in the Age of Galileo than church-versus-science as often Christopher M. Graney incorrectly portrayed. University of Notre Dame, 2015 In 1651, the Jesuit Giovanni Battista Riccioli published his book New Almagest wherein he outlined 77 arguments against the Copernican John G. Hartnett system and 49 arguments in favour of it. Most arguments against the vertically. The same argument could be he book comprises 10 chapters, Copernican system could be answered, 270 pages. The last half of made for cannon balls fired in different T at that time, but Riccioli, using the then directions on Earth’s surface. These the book largely consists of two available telescopic ‘observations’ of appendices: (a) the first English types of discussions and arguments the size of stars, was able to construct carried on for a century, and even Isaac translation of Monsignor Francesco a powerful scientific argument that the Newton got involved. What we now Ingoli’s essay to Galileo (disputing pro-Copernican astronomers could know as the Coriolis force, a ‘fictitious’ the Copernican system on the eve of not answer without an appeal to the force, resulting from the rotation of the Inquisition’s condemnation of it in greatness of God. the planet on the fired or dropped 1616) and (b) excerpts from the Italian Graney largely uses Riccioli’s New objects could not be measured with the Jesuit astronomer Giovanni Battista Almagest, which argues in favour required precision in the 17th century. Riccioli’s reports on his experiments not of the Ptolemaic system but of Riccioli carried out many precise ball with falling bodies. the hybrid Tychonic system, where dropping experiments. He intended to It is interesting to note that the cover Earth is immobile at the centre of the show that there was no deviation in of the book is taken from Riccioli’s universe, the sun, the moon, and stars the path of the falling bodies but he New Almagest (1651), and it depicts circle Earth; but the planets circle failed to get any conclusive result (due both the heliocentric system (top left) the sun. Riccioli built on the work of to many unknown and uncorrected with the Tychonic hybrid geocentric Danish astronomer Tycho Brahe, and errors). Also he had argued that experts system (bottom right). built a strong scientific case against the firing cannon balls would have to Most people think that around the heliocentric system, at least through correct for Earth rotation (if Earth did time of Galileo, and the beginning of the middle of the seventeenth century, rotate). However, it was found that the Copernican revolution, opponents which was several decades after the the ‘experts’ were nowhere that good, of the heliocentric worldview were advent of the telescope. they did not have that sort of precision primarily motivated by religion or The main two arguments presented or accuracy, and so that also was an dictates from the authority of the in the book, both scientific, are thesize inconclusive argument. Roman Catholic Church. However, of stars and the effect on falling bodies. We know today that the rotation this book demonstrates that this is of Earth has to be taken into account oversimplified and mistaken. for long-range military targeting of Falling bodies The author, Christopher M. Graney, projectiles (due to the Coriolis force). uses newly translated works by anti- If Earth were rotating, then a falling Even highly accurate snipers firing Copernican writers of the time to body should hit a point on the surface over 1,000 m are required to account demonstrate that they predominantly of Earth at a definite distance from a for not only wind direction, wind used scientific arguments and not vertical line to the surface, if dropped speed, air density, and elevation, but

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sphaera mundi (On the Sphere of the orbit is circular. Therefore if a star is World, c. 1230), the standard university close enough it should trace out a circle astronomy textbook for medieval on the sky as seen from Earth over the universities and seminaries, taught: solar year. “Also Alfraganus [9th century Thus the argument followed: if a Muslim astronomer] says that the star was seen to have a certain size least of the fixed stars which we but it was too distant to exhibit any can see is larger than the whole parallax, then it must be massively earth. But that star, compared with large, at least as large as the orbit of the firmament, is a mere point. Earth around the sun. It was argued Figure 1. Foucault’s pendulum in the Panthéon, Much more so is the earth, which that that must be the case, otherwise Paris 1 is smaller than it.” no disk for the star could be observed. Then with the invention of the The only response the Copernican also the Coriolis effect due to the telescope, it was observed that the star rotation of Earth. astronomers had to that was that God sizes were at least 10 times smaller. But is a great God and He made such In 1851, 200 years after Riccioli’s because the astronomers also observed publication of New Almagest, Léon large stars for His own glory. Riccioli solid disks for the planets out to Saturn argued that it was not the geocentrists Foucault first demonstrated his pen­ (and even phases for Venus) it was du­lum in Paris. It was the first accu­ who appealed to authority but the then believed that the telescope gave heliocentrists, in their answer to the rate demonstration of the effect of the true sizes of the stars also. Based Earth rotation on falling bodies. The ‘size of stars’ argument—purely a on telescopic measurements of the star scientific argument based on the best pendulum (figure 1) swings with a sizes, Riccioli formulated a version science of their day. regular period and as Earth rotates of the Brahe argument against the Graney points out that another who the path of the pendulum successively heliocentric system and in favour of made that argument was Johann Geog moves to the left (as viewed from the geocentric Tychonic system. Lochner in his book Mathematical above) tracing out a circle. This is the This is another irony: the popular Disquisitions Concerning Astronomical effect of the Coriolis force and proof myth goes that Galileo presented his Controversies and Novelties (1614).3 of the rotation of the planet. telescope to the geocentrists, and they And the leading Polish mathematician, Interestingly, the argument used by refused to look through it. Actually, Peter Crüger, likewise thought this was Galileo and other pro-Copernicans was as science historian James Hannam an almost watertight argument against that no effect on falling bodies could pointed out: the geokinetic view.3 be detected due to common motion. “So who refused to look through Galileo used an analogy about an Ga­li­leo’s telescope? According to insect flying inside of a moving ship the historical record, no one did for The real size of stars at sea. But Foucault’s pendulum proves certain. The argument was over what that analogy to be invalid. they could see once they did look.”2 Ironically, the geocentrists may not And Graney shows that Galileo’s have made their own error (assuming critics did he allegedly asked, and used the telescopes gave the correct size of Sizes of stars their observations against him. stellar disks) had they been privy to The size of stars argument went With the telescope, astronomers English astronomer Horrocks’ report as follows. Sizes of stars were first looked for parallax of the distant on the 1639 transit of Venus across measured by eye, before the invention stars but were not able to detect any the sun. During his observations, of the telescope. That is what Tycho parallax. In the geocentric universe, Horrocks noted that he observed the Brahe spent much of his time doing. Earth is immobile and hence no moon passing through the stars of the That gives a ‘magnitude’ for a star, parallax would be expected. In the constellation Pleiades. As the leading catalogued as magnitudes 1 through 6, heliocentric universe, Earth orbits the dark edge of the moon passed in front with 1 the largest and 6 the smallest. sun once per year, and in so doing, over of the stars they simply winked out. Of course, large meant bright and a six-month period it moves from one They vanished suddenly, meaning they small meant dim. It was based on side of its orbit to the other. Therefore did not transition to darkness as you these ‘measured’ sizes of stars that based on trigonometry, a foreground might expect if their disk was being Tycho Brahe developed an argument star should be seen to move against the slowly covered by the dark edge of the against Copernicus. (Even before more distant background stars between moon. This meant that the ‘measured’ Brahe, Johannes de Sacrobosco’s De these two extrema. But of course the size of the stellar disks was in fact

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spurious—due to a cause unknown pattern of maxima and minima. Since their argument against Galileo and the at the time. The sizes of the planets the lens is circular it produces a Copernican system is wrong. It was were correct because the telescope central bright maximum surrounded science against science and not science resolution was sufficient but it was by ever-reducing surrounding rings against religion per se. Both sides at not sufficient for distant stars. (see figure 2). The same effect would times used religion but the ‘battle’ was But Horrocks’ report was not be observed with the human eye4 (i.e. primarily fought with science. published until 1662, 11 years after a lens) or a pinhole (i.e. no lens). Riccioli published his New Almagest. However, Galileo didn’t know about And in 1659 Christian Huygens Horrocks’ report that demonstrated that References published his observations of stars the stars were really pinpoints as seen 1. The Sphere of Sacrobosco: An early 13th century treatise on astronomy, by Iohannes de using filtering (with smoked glass) from Earth. So instead, he claimed that Sacrobosco, ch. 1, trans Lynn Thorndike, 1949, wherein he showed the star sizes with a good telescope and looking at esotericarchives.com. 2. Hannam, J., Who refused to look through changed with greater filtering. Thus, a star through a thin beam, one could Galileo’s telescope? bedejournal.blogspot.com, it was soon realised that stars were observe the apparent motion of the 20 November 2006. actually point objects. In 1665 Riccioli star’s disk split by the beam. But there 3. Graney, C., Galileo fought dirty with his fellow scientists: the Italian astronomer had critics published his Reformed Astronomy, in is no disk to split except that produced inside and outside the Church, theatlantic.com, which he maintained his table of star by the telescope—so Galileo just could 17 October 2016. sizes but de-emphasized the star-size 4. This is what originally led Tycho Brahe to not have seen what he claimed. As establish different sizes (magnitudes) for stars, argument. Graney says: which, as already stated, turned out to be spurious. The lens in the human eye produces an Airy disk Of course, if the stars are so enorm­ “So, if the telescopic disk of a star when observing a star with the naked eye. ously distant and if their ‘measured’ does not exist outside the tele­ 5. Graney, C., Strange tales of Galileo and proving: sizes are spurious, then the major scope, and if it cannot be cut in splitting the stars, vofoundation.org, 26 April 2017. scientific argument the geocentricists half by some beam placed between 6. It is true that the modern-day geocentrists do not had against the heliocentrists evapo­ the telescope and the star, then accept that interpretation of the path of Foucault’s rates. By 1720 Edmund Halley argued pendulum, during the diurnal cycle. But I would Galileo’s reference to cutting a venture to say that they would not accept any that the star sizes were spurious, but star disk as ‘an effect which can be scientific evidence in support of the geokinetic some astronomers still maintained discerned perfectly by means of a system. the argument. A century later English fine telescope’ is strange indeed. It astronomer George Airy developed seems Galileo just made that up. In a full theoretical explanation for the science, it is not cool to just make spurious disk of stars. It explained both things up!” 5 the appearance of disks and why they varied in size for different stars. This effect is known as an ‘Airy disk’ and Conclusion results from diffraction effects in the Thus Graney argues that it was objective lens of the telescope. Because not until the mid-19th century before light has a wave nature adjacent beams complete arguments supporting the interfere with each other, creating a Copernican system were developed to refute Riccioli’s arguments. This means that Galileo hadn’t really proved the geokinetic system given the knowledge available at the time. The main two arguments were the size of stars, explained by their spurious observed disks, and the lack of precision of falling body experiments, after which it was shown via the Foucault pendulum that Earth does in fact move, rotating in its axis.6 Figure 2. Computer-generated image of an Thus Graney argues that the old canard Airy disk. The greyscale intensities have been th adjusted to enhance the brightness of the outer that astronomers of the 17 century rings of the Airy pattern. held onto religion and authority as

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