The Heavens, as Viewed from Earth

While Galileo will forever be remembered as the breakthrough astronomer of his time, he was only as good as the telescopes he could invent.

Galileo Galilei

Through the course of his patient observations, Galileo put forward some of the earliest evidence in support of the heliocentric model, proving that other planets revolved around the sun, that the moon was actually an imperfect celestial body with mountain ranges, and that the presence of spots on the sun imply it is not actually an untarnished heavenly body. Despite these cutting edge breakthroughs, Galileo remained bewildered by the shape of Saturn — was there a handle on the planet, or perhaps a series of satellite stars? In this case, he was unfortunately restricted by the technology he had available to him. Fifteen years after his death, with the aid of a higher resolution telescope, Christiaan Huygens discovered that the ‘handle’ was actually a tilted ring. (Shea, Artigas, Pg. 25) Good telescopes were a necessity to astronomers not only to make accurate observations, but also to dispel skeptics. Christopher Grienberger, a Jesuit astronomer and supporter of Copernicanism, initially expressed doubts while observing Venus through a telescope sent to Clavius. With continuous observation, however, Clavius realized that they were actually witnessing the phases of Venus as it orbited around the sun, and that it was not actually a byproduct of dysfunctional equipment. (Drake, Pg. 202) Impressed and convinced by Galileo’s instrument Grienberger became an outspoken supporter of his research despite still being required to teach Aristotelian physics under Jesuit doctrine. (Hockey, Pg. 442) The beauty of the telescope, as Galileo soon understood, was that it spoke for itself. By simply putting the telescope in the hands of a curious mind he could provide material evidence that the hegemonic understanding of physics was fundamentally flawed. The downfall of the telescope, however, was that it failed in convincing those who refused to look. Although limited by resolution power, it was Galileo’s inability to convert these adamant skeptics that would eventually curtail his research, leading to trials of heresy.

Galileo’s brilliant spyglass was capable of bringing distant celestial objects into an observable field of focus; a feat no other human had previously achieved. As he describes in Sidereus Nuncius, “It is most beautiful and pleasing to the eye to look upon the lunar body, distant from us about sixty terrestrial diameters, from so near as if it were distant by only two of these measures, so that the diameter of the same Moon appears as if it were thirty times…” (Galilei, Pg. 5V) Despite his clever design, the idea for such a device came to Galileo when he heard rumors about a spyglass invented by Hans Lippershey, a Dutch spectacle maker. Lippershey invented the first telescope as early as October 2, 1608, and within a few months Galileo had already created his own. (Humboldt, Pg. 317) By placing a concave and convex lens on opposite sides of a lead tube Galileo was able to observe far away objects as though they were immediately in front of him. With consistent trial-and-error he progressively improved the technology that would become the backbone of his Earth-shattering discoveries. Without hesitation, Galileo pointed his telescope at the Heavens and began recording observations in his daily diary.

Telescope diagram, detailed in Sidereus Nuncius

By simply enlarging one’s view of the moon Galileo revealed the presence of valleys and mountains, similar to the ones on Earth. (Galilei, Pg. 6R) Applying his advanced mathematical knowledge he was able to estimate the heights of lunar mountain ranges by measuring the tangents of solar rays. He determined the moon’s mountains to be larger than the mountains on Earth. He incorrectly assumed, however, a presence of a lunar atmosphere along with vast oceans. His telescope was considerably more powerful than Lippershey’s early prototype, but it was still limited in resolution, or the amount of detail a lens is capable of capturing. Galileo’s tool was incredibly effective when used to track the movement of distant celestial bodies over time, for example, but it struggled considerably in the observation of minute details. (Humboldt, Pg. 320)

This fundamental limitation of his telescope became a source of frustration as Galileo attempted to observe and explain Saturn’s odd shape. Under observation it sometimes appeared to have two handles, yet at other times they would disappear. He was excited to have made the discovery but was cautious to share anything until he could explain the mysterious motion of these unexplained objects. Anxious to tell his friends, Galileo wrote an encoded letter to Johannes Kepler and others in July of 1610. After much confusion, he followed up in a subsequent correspondence: “I have observed with great admiration that Saturn is not a single star but three together, which, as it were, touch each other.” Despite observing Saturn with his most powerful telescope prototype, sporting a magnification of over one thousand times, he began to lose faith in this original theory. (Shea, Artigas)

Over the next two years Saturn’s two stars diminished until they were no longer visible, greatly unnerving Galileo. (Fahie, Pg. 108–110) In a letter to Mark Welser in December, 1612 Galileo laments: “Are, perhaps, the two smaller stars consumed like spots on the sun? Have they suddenly vanished and fled? Or has Saturn devoured his own children? Or was the appearance, indeed, fraud and illusion, with which the glasses have for so long mocked me and many others who have observed with me?”

Saturn’s appearance changes based on its tilt relative to Earth

The telescope which had once been the source of Galileo’s certainty was now the source of doubt; had his eyes betrayed him? The behavior of Saturn perplexed him so profoundly that he briefly considered the possibility that his sceptics were right. Could it be possible that everything ‘the glasses’ had shown him was merely a fraud or an illusion, as his opposition had so frequently accused? He continued in the letter to Welser: “I cannot resolve what to say in a change so strange, so new, so unexpected… the weakness of my intellect, the terror of being mistaken, have greatly confounded me.” Galileo assumes that it is his own intellectual shortcomings hindering his research when in reality the details of Saturn’s ring were simply not visible with a telescope of such low resolution power.

Despite patient observation throughout the rest of his life, Galileo was never able to explain Saturn’s odd shape. In a 1640 letter to former student Benedetto Castelli, Galileo, already blind and approaching death, admits: “It will be for the future and for others to make observations… that is, if there will be any persons curious enough to do what I, from the same motive, have done for so long a time.” Only fifteen years after his death, Christian Huygens solved the riddle explaining that Saturn was surrounded by a ring, although mistakenly assuming it to be composed of a single, solid entity. Huygens also discovered Saturn’s moon Titan in 1655, the clearest of the planet’s moons and even within the range of Galileo’s telescope. (Andriesse, Pg. 122, 149)

Christian Huygens

Although Galileo understood the importance of recording Saturn’s quirks, he recognized the potential that such uncertainty could also vindicate his opposition. In defense of his instrument, and perhaps a bit uncertain himself, Galileo diverted his attention to some of the other universal mysteries. While in Rome in 1611 to have his telescopic discoveries approved, Galileo was able to accurately observe and estimate the periods of Jupiter’s moons. In observation of the sun, Galileo and other astronomers were once again limited by the equipment available at this moment in history. The human eye cannot glare directly at the sun, which presents a challenge not encountered in the observation of other celestial bodies. Astronomers initially used colored or dirtied lenses until Castelli invented a new method of projecting the satellite’s image onto a screen, a breakthrough moment which revealed the presence of large spots on the sun’s surface. (Shea, Artigas, Pg. 40–41) With this new tool Galileo observed that the spots were not permanent features; they actually appeared and disappeared continuously. Unlike previous natural discoveries, such as the new world by Columbus, Galileo’s discovery of sunspots implied the beginning of an entirely new natural philosophy. (Sobel, Pg. 58)

Spots on the Sun’s surface challenged the notion of celestial perfection

After less than three years of working with telescopes, Galileo had consistently deconstructed astronomical and physical beliefs held for centuries. As his teachings grew in popularity, however, his opposition increased in intensity. Monsignor Piero Dini, a friend of Galileo’s, hinted at the biggest hurdle facing him in a May 1611 letter to Cosimo Sassetti: “Every day Galileo converts some of the heretics who did not believe him, although there are still a few who, in order to escape knowing the truth about the stars around Jupiter, do not even want to look at them.” Despite the approval he had received from some high ranking Jesuits, the Council of Trent set a precedent that the right to interpret scripture was held exclusively by the Church, and in cases of uncertainty a literal interpretation was assumed. From this perspective, anything written in scripture is true for the simple reason that it was written by God. According to Cardinal Bellarmine, an attendant at the Council of Trent and author of Controversies of the Christian Faith: “There can be no error with scripture, whether it deals with faith or with morals, or whether it states something general and common to the whole Church or something particular and pertaining to only one person.” (Blackwell, Chapter 2) This poses a considerable problem for Galileo, whose observations discredit the many instances in which the Bible takes a geocentric stance. If the scripture states that the sun rises and sets, and the scripture is infallible, then how could it be true that the sun actually remains still? In response to such opposition, Galileo was once quoted as saying: “It would seem bold, not to say reckless, to want to limit the knowledge and the working of nature to what I can understand of it.”(Shea, Artigas, Pg. 42) Instead of celebrating intellectual stagnation in the name of God, Galileo favors a constantly evolving dialogue in which new discoveries are not shunned simply because they are an inconvenient truth. The battle with those who seek to limit knowledge is quite reminiscent of modern discourse; an unfortunate reminder that the more things change, the more they stay the same. Even as scientific instruments have become ever more advanced, ignorant people still “do not even want to look at them.”

Cosmic maps according to Ptolemy, Copernicus, and Brahe, relatively

When dealing with opposition Galileo consistently makes a detrimental error: he fails to recognize that theological opponents have a different standard of truth than his own, and he writes it off instead of confronting it. Cardinal Bellarmine was steadfast in his belief that scripture must be interpreted literally, for it was divinely inspired by the Holy Spirit. According to Dr. Richard Blackwell in Galileo, Bellarmine, and the Bible, this standard of truth would be considered de dicto, or ‘by virtue of being said.’ Along these lines, concepts such as geocentrism are undeniably true on matters of faith and morals. Galileo was quick to write off such a perspective, “They wish never to raise their eyes from those pages — as if this great book of the universe had been written to be read by nobody but Aristotle, and his eyes had been destined to see for all posterity.” (Sobel, Pg. 53) Galileo viewed himself to be a sort of prophet, ‘illuminated by divine grace’ to invent the telescope. (Machamer, Pg. 186) Where he falters, however, is that he forgets how prophets like Jesus were treated throughout history. Jesus could miraculously feed a village with thousands as witness, yet others would refuse to believe unless they could see it for themselves. Galileo’s revelations regarding the cosmos were a miracle in that they further substantiated God’s creation as something far more expansive and profound than it ever could have previously been imagined. Given his opponents’ conviction in regard to what they held as true, Galileo would have benefitted from distinguishing standards of truth. Monsignor Dini confirmed in a May 1615 letter: “Many Jesuits secretly share your position although they remain silent.” These covert Galeleists were sympathetic to his scientific theories, yet Galileo insisted they were actually more than theories, they were fact. By presenting his findings as facts, he limited his knowledge of the workings of the universe to what he could presently understand of it. Thus, he was lacking the most crucial tools needed to gain approval of his theories — the ability to speak hypothetically, and with humility. (Shea, Artigas Pg. 74)

If the telescope was Galileo’s instrument for observing the cosmos, humbleness would have been his instrument for convincing opponents of his verity. Cardinal Bellarmine was convinced in the infallibility of scripture, so arguing against scripture with him would be quite the futile endeavor. In response to skeptic Ludovico delle Colombe, his first theological opponent, Galileo sarcastically attributed the moon’s perfect roundness to a “crystalline substance that is transparent and invisible.” Such a dismissive attitude toward skeptics served only to vindicate them in their beliefs, making it considerably more difficult to convince them as they began sounding the alarms for heresy. (Shea, Artigas, Pg. 45) In a sense, similarities can be drawn between Galileo and the impoverished street singers found throughout Italy during the Renaissance. These singers published their own cheap pamphlets and were faced with increasing censorship, forcing them to engage in more subtle political commentary. (Salzberg, Pg. 217) When faced with censorship from powerful authorities, they found a way to make themselves and their ideas visible without directly antagonizing their opponents. The comparison fails, however, for Galileo’s revelations about the cosmos were far more consequential to human history than the plights of homeless Florentian beggars.

While Galileo may have felt quite alone in his battle against the Church’s authorities, he was only a part of the opening act of what would become centuries of tension between science and religion. If anything, Galileo fell victim to ill-intended, power-obsessed theologians using the Church’s name in vain. Despite the accusations of these theologians, Galileo was a proud Catholic who sought astronomical knowledge in part for the pride it would bring the Church over Protestantism. He found it difficult to understand that the Church could ever desire ignorance over knowledge, and he believed that a strong scientific understanding could coexist with a reverence for Scripture and the Fathers of the faith. (Sobel, Pg. 140) A stronger telescope would therefore have aided in Galileo’s understanding of Saturn, and perhaps also the climate on the moon (or lack thereof), but it would have also suffered the tragic condition of failing to convince those who simply refused to look.

Galileo viewed himself as a prophet destined to interpret the true physical nature of celestial bodies. While his intellect certainly guided him to many profound discoveries, I believe he could have performed better in communicating these new theories to others. It is possible that he became carried away in delusions of grandeur, at least in that he viewed his own observations as unassailable. The true beauty of the telescope is that when it is put in the hands of a curious mind, another set of eyes is given a window through which they can begin patiently observing the cosmos, corroborating the conclusions of observers before them. Even with the strongest telescope it is likely Galileo would have still failed in convincing skeptics, for he sought authority as the one, trusted interpreter of the cosmos. Such a self-proclaiming prophet would prove to be incompatible with the Catholic Church, which sought a rather identical interpretive authority. Ironically, such a posture would also be incompatible with modern science, and the celebration of a collaborative flow of information. Galileo’s telescope was sufficient to bring into focus the most controversial natural observations during the Renaissance. Thus, the instrument to which he should have dedicated more of his life improving is instead the ability to communicate his message to skeptics.

Galileo’s Trial in Rome


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Blackwell, R. J., & Foscarini, P. A. (1991). Galileo, Bellarmine, and the Bible: Including a translation of Foscarini’s Letter on the motion of the Earth. Notre Dame: University of Notre Dame Press.

Drake, S., Swerdlow, N. M., & Levere, T. H. (1999). Essays on Galileo and the history and philosophy of science. Toronto: University of Toronto Press.

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Salzberg, R. (2016). ‘Poverty Makes Me Invisible’: Street Singers and Hard Times in Italian Renaissance Cities. Italian Studies, 71(2).

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Sobel, D. (1999). Galileo’s daughter.

Journalist, entrepreneur and student - Boston College, University of Otago. Adventurer and consultant for conducting business in Asia. Ethereum tips: muse.eth

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