In the early seventeenth century, Galileo Galilei began the construction of a device that would transform the scientific world. Galileo did not invent the telescope but his improvements on it made him the most scientifically successful user of this instrument in his time. However, Galileo would not stop at scientific discovery. The father of three successfully marketed the improved instrument to the Senate of Venice and the Grand Duke Cosimo II of Tuscany in hopes of possibly furthering his career.
In the telescopes transitional form, Galileo is able to obtain a salary raise and a permanent position at the University of Padua but he is disappointed with this offer and continues to make improvements on the telescope. He realizes that his ties to Cosimos court, he taught the Grand Duke when he was younger, could be used to his advantage. The medium for his objective was The Sidereal Messenger. This treatise gives a direct dedication to Cosimo and his court with the hope that he will gain its favor and patronage from the ruler of his native land.
It is also the medium through which he conveys his advocacy of the Copernican system, particularly using his telescopically enhanced observations of the moons irregular surface and Jupiters moons. Galileo saw the opportunity to gain a great deal from his telescope from the beginning of its conception. The senate of Venice offered him an increase in salary and a permanent appointment at the University based on Galileos first improvement which only magnified objects by ten times . He realized that the telescope could improve his financial situation but he was smart enough to not settle for his first offer.
He quickly wrote to the Tuscan court about his discoveries. When Galileo heard that the Grand Duke Cosimo and his three brothers were astonished by his almost supernatural intelligence, he realized that he could use this to his advantage. The brilliant Florentine patrician had ties to Cosimos court because he tutored him in math as a child. The courts were also very interested in these dazzling things and wanted them for military purposes . Cosimos court did not stray from this generalization and Galileo knew it.
It can also be theorized that this position was much desired and after he attained the position it combined the advantages of those tow professional identities while avoiding many of their drawbacks. His observations of the irregular surface of the moon and his discovery of Jupiters moons gave him much to work with. Galileo informed the court of his plan to place the name of Cosimo de Medici II in the stars, as the ancient sages did with the most excellent heroes of their time, by naming the newly found stars, or moons, after him. Clearly this would help him gain the Dukes favor.
The second step was to dedicate the treatise on his telescopic discoveries to the Grand Duke. He opens his book with a reverent and adulating dedication. It contains many deifying words, often giving the Duke illustrious and almost divine exploits. This type of dedication was common practice for scientists who needed funding but his position is furthered by the fact that he is naming heavenly bodies and not earthly things. Because of this, the Dukes name would me mentioned in the same breath as heroes such as Jupiter and Mars or Hercules and Mercury.
In succeeding pages, the author continues to worship the Duke and his agreeableness of manners, splendor of the royal blood, majesty in actions, and breadth of authority and rule over others. It is clear from the dedication letter to the Duke that Galileo is writing for two audiences, one of these audiences being his scientific peers and the other being the Grand Duke Cosimo II. Obviously, Galileo had the Dukes patronage in mind and all the key steps in attaining this patronage had been completed except proving that his observations were true.
After dedicating his work to Cosimo, sending him a copy of his observations and a telescope to verify them, Galileo went personally to Tuscany to explain his observations . His visit was very successful and Galileo was granted a position at the Tuscan court by the Grand Duke Cosimo II. During this time, he was also granted the position of principal mathematician at the University of Pisa, a position that incurred no further duties by Galileo . He now had a very valuable resource in the court and a wonderful job. Galileo used his telescopic observances to his advantage and his dedication to the Duke was very profitable.
However, Galileos work was not purely written in order to attain patronage from the Duke. The scientific implications of The Sidereal Messenger were the most significant part of the treatise. Galileos observations were revolutionary because they contradicted the scientific ideas of his time. In particular, Galileo advocates the Copernican theory with his telescopic observations of the moon and the moons of Jupiter. This is in direct contradiction to the Ptolemaic and Aristotelian theories that dominated the era. After he first pointed his telescope to the sky, he became intrigued with the irregular surface of the moon.
According to the prevalent geocentric theory of the universe, the heavens were perfect and unchanging. In a letter about his first observations referring to the moon, Galileo states, it is shown to be such that sane reasoning cannot concluded otherwise than that it is full of prominences and cavities. Galileos observations would be further improved by his production of a device that magnified thirty times. This letter also explained his observations of Jupiters moons. The fact that Jupiter had moons implies the Copernican theory because the earth is no longer the only center of motion as proposed by the Aristotelian universe.
This letter is basically an outline and prequel for The Sidereal Messenger that Galileo would publish nine weeks later. The Sidereal Messenger explains Galileos telescopic observations in detail. The first section is on the moon and for coherence and cogency of argument is the best part of the book. In this section, the author gives a report of the motion of light and shadow over the moons surface. He is constantly comparing the surfaces of both the earth and the moon in order to stress their affinity and to further advocate the Copernican theory. He says the spots of the moon are like a ridge of very high mountains turned away from the sun.
In particular, he compares a large cavity in the center of the moon to a region in Bohemia in respect to its shadow and illumination. To suggest that the moon has mountains and is not perfectly smooth is to also suggest that the theory of the Aristotelian universe is wrong and the heavens are not perfect. He also provides illustrations of his observations in order to show the earth-like nature of the moon. However, this is not the first time that people noticed irregularities in the moons surface. The spots are visible to the naked eye but not in as great detail.
Therefore, observers suggested that the different parts of the moon reflected light differently and caused these spots to occur. This naked eye observation also presented problems because the outline of the moon is smooth, yet Galileo suggested that it was filled with mountains and cavities. He disproved this observance by stating that the valleys at the edge of the visible hemisphere are filled in by the peaks of successive ranges of mountains in front of and behind them. He also suggests that just as around the Earth, there is around the lunar body a certain orb of denser substance than the rest of the ether.
This substance prohibits the vision around the edges of the lunar body and hides the periphery of the moon exposed to the sun. Next, Galileo proceeds to explain that the Earth does in fact reflect solar light onto the moon and it is not to be excluded from the dance of the stars. This is another attempt to advocate the Copernican theory of the Universe, which suggests that the Earth is a heavenly body that moves and transmits light. The great observer then turned his attention to the stars. He notices that some objects, the fixed stars, are magnified less than others, the planets.
In order for this to be true, the fixed stars would have to be at a very large distance from Saturn, the outermost planet of this time, therefore separating the planets from the fixed stars. This supported the Copernican theory. He then goes on to his observations of the moons of Jupiter. In short, he makes almost nightly observations of four heavenly bodies around Jupiter with his telescope and reports that he has found four stars, or Medician planets as he calls them, that travel around Jupiter. This suggests that the Earth is not the only center of motion in the universe and further advocates the Copernican system.
Galileo successfully arranges his observations of the heavenly bodies through a magnifying instrument into an incentive for patronage and a promotion of a revolutionary universal system. He gains the patronage of his former student by dedicating to him his revolutionary work on astronomy while also suggesting that the present universal system is wrong and he can prove it. Although the telescope helped him to observe objects with greater detail than other scientists of his time, it cannot be forgotten that Galileo had a mysterious ability as an observer and scholar.