Why Galileos use of the Telescope Helped to Condemn him

Galileo Galilei (1564-1642) is well known for having dared to defy the Roman Catholic Church by agreeing with the theory, formulated in 1512 by the Polish astronomer Nicholaus Copernicus (1473-1543), that the planets including Earth orbited the Sun. Galileo paid for his “heresy” by spending the last eight years of his life under virtual house arrest. However, what is less well known is that it was the tool he used in his researches, as much as the conclusions he came to, that got him into trouble with the Church and the Inquisition.

 The telescope

 Copernicus had come to his conclusions on purely theoretical grounds, without making any direct observations of the motions of the planets. Even had he wished to do so he would have been very limited in what he could see, because the telescope was not invented until after his death.

 The first practical telescope is believed to have been developed by Hans Lippershey, a lens maker of Middleburg in the Netherlands, in 1608. However, it is not known who first discovered that if one looked through two lenses, one concave and the other convex, distant objects appeared to be much closer. What Lippershey did differently was to apply for a patent for his “far sight” device, or “tele scope”, which is why he is credited with being the inventor.

 Galileo and the telescope

 Attempts to credit Galileo with the invention of the telescope are certainly wide of the mark, but he did make a number of significant improvements in telescope design, being able to increase its power of magnification from 3x to 30x very soon after first experimenting with a Lippershey instrument.

 Galileo’s real place in the story of the telescope is that he was the first person to use it as a means of trying to prove the heliocentric theory propounded by Copernicus, as well as making a number of other important astronomical discoveries.

 However, there was a problem when it came to dealing with the Church, in terms of demonstrating his discoveries. This was that the telescope was doing something that enabled mere mortals to do things that had not been ordained by Man’s creator. It was acceptable to wear lenses as spectacles, because that was only restoring one’s sight to the level that God had given one, but the telescope went much further than that. Only God was “all seeing”, and to seek to emulate God in this respect was nothing short of heresy.

 There were many people at the time who refused to look through a telescope, in the belief that they would commit a sin by so doing. One such example was Cesare Cremonini, a philosopher from Padua who was both a friend and a rival of Galileo. Galileo had used a telescope to prove that there were mountains on the Moon, but his invitation to Cremonini to see this for himself was turned down.

 When seen from the point of view of the Church, it has to be admitted that there was some justification for their stance that the telescope deceived mankind and was therefore an instrument of the Devil. Early experiments with telescopes, which were nothing like as powerful or carefully constructed as those used today, did not always produce consistent and trustworthy results.

 Galileo’s own observation’s sometimes told against him in this respect. For example, he claimed that the planet Saturn had two companions, one on either side. However, he was unable to repeat this observation some months later, as the companions had apparently disappeared. What had happened was that his first viewing through his telescope had shown the edges of Saturn’s rings when turned at a certain angle. His later viewing was when the rings were edge-on when seen from Earth and therefore not visible.

 Galileo and the Inquisition

 When Galileo was called upon by the Inquisition in Rome to recant the views expressed in his “Dialogue Concerning the Two Chief World Systems” he was already off to a poor start. Not only was he committing a heresy by supporting the Copernican view of the solar system, but he was attempting to prove his point by using an instrument of the Devil, namely the telescope.

At least Galileo escaped the fate of Giordano Bruno, who, in 1600, was burned at the stake for his views, which included the daring suggestion that the Sun was no different from the other stars, only much closer. However, Galileo was banned from publishing any further works, and he spent his remaining years summarising his earlier work, particularly in physics and mechanics.

 It is perhaps stretching matters too far to suggest that, had he left his telescope at home, Galileo might have avoided being silenced by the Church. However, it is also fair to say that it was foolish of him to expect a sympathetic hearing when he appeared before his inquisitors armed with the very instrument that had caused so much trouble. They were hardly likely to accept any invitation to “see for themselves”.

Galileo must surely have known that he stood no chance of convincing his accusers to change their minds, so maybe he decided to go down with all guns blazing, to satisfy himself if nobody else.