Based on sidereus nuncius why is galileo important

You are commenting using your Twitter account. You are commenting using your Facebook account. Notify me of new comments via email. Notify me of new posts via email. You have to take the data of history seriously. Culture is part of the unholy trinity—culture, chaos, and cock-up—which roam through our versions of history, substituting for traditional theories of causation. Skip to content. Like this: Like Loading August 24, at pm. Many thanks for this review.

Can you cast further backwards some time, please? September 11, at pm. August 15, at pm. August 17, at pm. August 21, at am. I have removed this comment because: 1 It has nothing to do with the post you have attached it to 2 If you want to argue with Professor Graney about a paper that he posted on arXiv then you should do so on arXiv and not on my blog.

I would contend that there is still some relevance in discussing 1 to what extent discs of the size Marius claimed were treated as evidence against Copernicus. But I suppose ymmv. Leave a Reply Cancel reply Enter your comment here Fill in your details below or click an icon to log in:. Email required Address never made public. Name required. Search for:. John S. Wilkins 30th August Culture is part of the unholy trinity—culture, chaos, and cock-up—which roam through our versions of history, substituting for traditional theories of causation.

Blog at WordPress. Follow Following. The Renaissance Mathematicus Join 15, other followers. Sign me up. Already have a WordPress. Log in now. Loading Comments Email Required Name Required Website. Perhaps another reason led Galileo to go much further than a mere description of what he saw and also beyond the reference that the reader can share. This is the subject of a hypothesis that I shall propose but first it is necessary to point out another important step in advance.

The description is enriched by dozens of observations collected night after night with meticulous precision and reported in the text with exact drawings, one for each day. Much earlier in the book when Galileo reaches the end of his observations, he introduces the hypothesis that an atmosphere surrounds another celestial body—Jupiter in this case see above note 6. However, it must be said that the relative position and the angular distance of a star or planet is an easily measurable quantity and therefore not ambiguous.

Instead, it is difficult to measure the light intensity of an object in the black night sky, particularly if this object is observed very close to another brighter body. This is exactly the case when the satellites of Jupiter are observed by Galileo shortly before or after their occultation by the far larger body of the planet. He deals with it some pages earlier when describing the difficulty of measuring the apparent magnitude of the stars he had just discovered.

Indeed, he describes how the instrument behaves very strangely and shows different magnifications depending on whether the observed object is a planet or a star. In fact, Galileo could not know the physical explanation of the optical aberration phenomenon which is usually associated with the use of an optical instrument. Therefore, he is hesitant to give the description of a mechanism according to which the instrument is apparently able to enlarge the observed objects in different ways, i.

At this point, Galileo did not have the time to pursue this matter because he urgently needed to make public his numerous observations of all visible objects in the sky of Padua as soon as possible. In the winter of , despite not being an astronomer he was about to totally and definitively revolutionize the image of the sky and also suggest the need to overhaul the model of the Cosmos through his rich innovations.

Indeed, the Aristotelian-Ptolemaic model endorsed by the Church encountered a great deal of difficulty in facing up to the whole complex set of new ideas discovered by Galileo. This depended on the geometric complexity required to take the new, observational data into account and also on the weakness of some of the principles on which the Aristotelian-Ptolemaic system was based.

These principles were now being demolished. The Copernican model was published almost 70 years earlier and was still seen only as an original, mathematical exercise to provide new ephemerides. However, while there were several difficulties with the Copernican system, the situation for its Ptolemaic counterpart was undoubtedly even worse.

This observation may indeed appear superfluous when compared with the astonishing announcement of the existence of four new planets. Moreover, Galileo does not provide many details regarding this problem although he was precise and meticulous in describing these observations. Notwithstanding, these references appear significant.

Galileo advances a hypothesis that can explain this apparent variability of the light reflected by satellites after a very long thought process. Initially, he provides the hypothesis that their orbits can be highly elliptical, being the major axis along the line of sight of the observer. This meant he could explain the weakening of the light by the increased distance of the satellite. Galileo certainly knew from his previous experience that light intensity decreases with increasing distance from the source.

Galileo saw that the brightness of the satellites was at its minimum when they came close to the planet. The only theoretical possibility is thus that the satellite moves away far from Jupiter, its center of motion and therefore that the orbit must be greatly elliptical in relation to the weakening of the light output observed and recorded by Galileo. The logic that supports this argument may seem compelling. Anyway, this behaviour of the phenomenon is not compatible with the previous hypothesis which seems artificial.

However, this hypothesis is a scientific-literal artifice used by Galileo to lead up to a second explanation. In this explanation, he returns strongly to the hypothesis that an atmosphere could surround a celestial body—Jupiter in this case. The presence of a dense shell would weaken the light absorbing a large proportion of the emission from satellites.

It is fascinating to imagine that Galileo had a common purpose for giving an account of two different events which acquires the value of a universal statement— planets have a shell of air around themselves.

Nevertheless, this statement is not particularly significant if it is limited to an explanation of observational data but if used as a starting hypothesis which is well supported by observations, it could have deep, cosmological implications. It would indeed be linked to the disputes concerning the De revolutionibus orbium coelestium of Nicolaus Copernicus.

In fact, if the Moon and the planets have an atmosphere in their circular movement around their center-of-motion, then the motion itself is not incompatible with the existence of an atmosphere.

Also, if this logical consequence is valid for the Moon and planets as shown by Galileo and if they are similar to the Earth, this obstacle is overcome by imagining an Earth moving around the Sun. Therefore, the movement of the Earth around its axis and around the Sun does not imply the atmosphere is stripped away.

However, if this hypothesis is correct, why was Galileo not more explicit? This is impossible to answer. Again, it should be recalled that the heliocentric system was not accepted by most theologians, astrologers, astronomers and scholars, even if De revolutionibus had not yet been rejected. All these observations were to be as fundamental as the previous ones. Galileo discovers Saturn to have a strange shape like a small olive.

Venus was watched nightly and every week which showed phases similar to those of the Moon. It therefore became geometrically evident that the Mother of Loves was moving around the Sun as Copernicus had suggested, unheeded, for decades.

The next step examined is that in which Galileo describes what he sees pointing his telescope towards the nebulae, or nebulous stars. Immediately he proposes a new radical change in the interpretation of those indistinct spots that had long been considered one of the most mysterious objects in the sky when viewed with the naked eye.

Philosophers, priests, astronomers had provided several proposals to explain their nature which were mostly mythologically based. This is, once again, a real revolution. In fact, the interpretation of these objects changes dramatically because Galileo reveals that they are composed of myriad stars which are so weak and apparently mutually close that they cannot be distinguished by the human eye.

Thus one has the perception that they are made of a continuous material. This scheme supports the heliocentric model.

But another revolution which would have to wait several more centuries to be accepted was smouldering under the ashes. It was proposed more than two thousand years ago and it concerns the real composition of nature of matter around us. Does matter have a continuous structure or is it composed by the atoms that Democritus and Leucippus imagined in a remote corner of Greece?

In those years the implications of the atomistic hypothesis were rather hazardous. Asking yourself this question at that period had a dangerous implication because the atomic theory was strongly opposed by the Church. But for a time it seemed that disagreement would not necessarily lead to condemnation.

Galileo made a triumphant journey to Rome in , where he stayed with the Jesuit astronomers, who confirmed his observations in almost every particular. He received the blessing of Pope Paul VI, and more importantly, one of the Pope's advisers actually agreed to look through the telescope. This was Cardinal Robert Bellarmine: a great intellectual, Bellarmine had friends in common with Galileo, and had studied astronomy in his youth.

However, the cardinal had also crusaded ardently against heresy, and sixteen years earlier had condemned the celebrated Giordano Bruno to death for, among other heresies, preaching a form of Copernican philosophy. Thus the support of this man encouraged Galileo in his hope that the Church might come to recognize not only his discoveries, but the world-view they hinted at—the heliocentric sun-centered philosophy of the Copernican system.

For by this point, Galileo considered heliocentricity as providing the only model that fit all his facts. Copernicus's model, with Kepler's adjustments which included changing the orbits of the planets from circles to ellipses not only made mathematical sense, but it explained all of his new data. The phases of Venus occurred because the sun lay between the earth and Venus during part of the year; the surface of the moon suggested that Earth was just one among many similar planets; the moons of Jupiter implied that many other planets had satellites orbiting them even as they themselves orbited the sun.

The evidence convinced Galileo, and in the two years after his journey to Rome, while he occupied himself with continued observation of sunspots and non- astronomical work on the properties of floating bodies, he began to speak of the Copernican system as fact, not theory.