The Copernican Revolution
"The Copernican Revolution was a revolution in ideas, a transformation in man´s conception of the universe and of his own relation to it."
Chapter 1
The Ancient Two-Sphere Universe
1543, Nicholas Copernicus proposed a solar system, in which the universe revolves around the sun, not around the Earth.
This caused a transition form medieval to modern western society. (It also affected mens values.)
In ancient civilizations we can see that there was a cosmology, guided by the observation of the sky. It has been important for men to try to describe what it out there, in order to feel that they have a place and belong somewhere. But now a days, in order to believe a cosmology, it need to supply a psychologically satisfying world view and explanations for phenomenas.
How did the ancient civilizations track the sun?
Gnomon.
By this people were able to tell time, solstices, that the sun rises from east to west, the seasons and were able to create calendars.
1543, Nicholas Copernicus proposed a solar system, in which the universe revolves around the sun, not around the Earth.
This caused a transition form medieval to modern western society. (It also affected mens values.)
In ancient civilizations we can see that there was a cosmology, guided by the observation of the sky. It has been important for men to try to describe what it out there, in order to feel that they have a place and belong somewhere. But now a days, in order to believe a cosmology, it need to supply a psychologically satisfying world view and explanations for phenomenas.
How did the ancient civilizations track the sun?
Gnomon.
By this people were able to tell time, solstices, that the sun rises from east to west, the seasons and were able to create calendars.
Constellations are part of that human need to put things into patters (Thinking Fast and Slow).
The stars also act like the sun. They complete circles around the Earth every 23 hours 56 minutes. So we get to see them every night in the same positions at the same time (but they do not move… we move). They always remain still; it’s just that the sun won’t let us see them.
People in the south observe totally different stars that the ones in the north. The ones in the south observe the stars longer but don’t see the circumpolar stars (only the north), while in the north they observe more stars but for a shorter time. The stars in the north remain constant in the same position.
The stars also act like the sun. They complete circles around the Earth every 23 hours 56 minutes. So we get to see them every night in the same positions at the same time (but they do not move… we move). They always remain still; it’s just that the sun won’t let us see them.
People in the south observe totally different stars that the ones in the north. The ones in the south observe the stars longer but don’t see the circumpolar stars (only the north), while in the north they observe more stars but for a shorter time. The stars in the north remain constant in the same position.
Two-sphere universe:
There is the world and then there are stars and then the sun, all of this contained in a sphere. Outside this sphere is nothing (the sky looks domed).
People believed that a sphere was the most perfect thing, and that was most fitting for man’s home, since the Earth was a sphere. The outer world (stars, sun, also had to be in a sphere).
There is the world and then there are stars and then the sun, all of this contained in a sphere. Outside this sphere is nothing (the sky looks domed).
People believed that a sphere was the most perfect thing, and that was most fitting for man’s home, since the Earth was a sphere. The outer world (stars, sun, also had to be in a sphere).
Chapter 2
If it weren’t for the planets we might still believe in the 2 sphere universe.
Term planet comes from the Greek word “wanderer”.
It was until after Copernicus died that they were distinguished as planets. (The sun was also considered a planet)
The only thing that resembles the planets we have now is that the planets in the 2 sphere universe is that they had a certain motion, only that this one was around the ecliptic and around the Earth.
Planets moved eastward through the constellations, this was considered the “normal” motion. But planets don't move at uniform rates.
All of the planets (except the moon and the sun) are interrupted by brief intervals of westward or “retrograde” motion. As seen in the picture.
Term planet comes from the Greek word “wanderer”.
It was until after Copernicus died that they were distinguished as planets. (The sun was also considered a planet)
The only thing that resembles the planets we have now is that the planets in the 2 sphere universe is that they had a certain motion, only that this one was around the ecliptic and around the Earth.
Planets moved eastward through the constellations, this was considered the “normal” motion. But planets don't move at uniform rates.
All of the planets (except the moon and the sun) are interrupted by brief intervals of westward or “retrograde” motion. As seen in the picture.
“The problem of the planets became simply that of explaining and the observed deviation from average motion through the stars in terms of a corresponding deviation of each planet from its singular orbit.”
There was the sphere of the stars and somewhere between this sphere and the Earth, the planets were located, turning in their own orbits.
Problem:
The further away the planets were, the longer it took them to move around the zodiac. The closer they were, the shorter time it required. The problem was presented by the sun, venus and mercury (the 3 orbits closest to Earth). They all took around the same time to revolve around the Earth.
There was the sphere of the stars and somewhere between this sphere and the Earth, the planets were located, turning in their own orbits.
Problem:
The further away the planets were, the longer it took them to move around the zodiac. The closer they were, the shorter time it required. The problem was presented by the sun, venus and mercury (the 3 orbits closest to Earth). They all took around the same time to revolve around the Earth.
They located the planets depending on how long they took to complete a circle around their orbits.
Theory of Homocentric Spheres:
Homocentric spheres have a common center: the Earth.
The problem within this theory was that it supposed that the planets distance to Earth cannot vary, but when retrogression happens, planets seem brighter.
Epicycle-deferent system:
“The new mathematical mechanism for the planets consists of a small circle, the epicycle, which rotates uniformly about a point on the circumference of a second rotating circle, the deferent.”
The planet is located on the epicycle and the center of the deferent coincides with the center of Earth.
Retrograde motion: deferent and epicycle move eastwards but when the planet on the epicycle moves closer to the Earth it kind of produces a westward motion.
FIGURE 19
The epicycle-deferent systems explains why the planets appear brighter. It is when they retrogress that they are closer to the Earth.
The problem with this system is that the epicycle was made to revolve exactly 3 times and the retrograde loops always seem to occur in the same places. In a real life this is not so true, it varies slightly, it averages more than 3 retrograde lops in each trip around the ecliptic.
Although the systems described and explained one of the main problems, there were other irregularities to be considered.
In the cycle of the diurnal motion, a planet is not always seen at the same position on the ecliptic as where the model says it should be.
Ptolemaic system:
Ptolemy was the first to put together a set of compounded circles to account for the observed quantitative regularities in the motions of all 7 planets.
Then the problem of the planets became a problem of design.
None of the theories mathed the observations that had been made. The planets were the greatest problem.
It took 1800 years to change theories. It was like if every astronomer in that time was seeking through the same spectacles.
The logical structure of a scientific revolution:
“A conceptual scheme, believed because it is economical, fruitful and cosmologically satisfying, finally leads to results that are incompatible with observation; belief must then be surrendered and a new theory adopted; after this the process starts again.”
Theory of Homocentric Spheres:
Homocentric spheres have a common center: the Earth.
The problem within this theory was that it supposed that the planets distance to Earth cannot vary, but when retrogression happens, planets seem brighter.
Epicycle-deferent system:
“The new mathematical mechanism for the planets consists of a small circle, the epicycle, which rotates uniformly about a point on the circumference of a second rotating circle, the deferent.”
The planet is located on the epicycle and the center of the deferent coincides with the center of Earth.
Retrograde motion: deferent and epicycle move eastwards but when the planet on the epicycle moves closer to the Earth it kind of produces a westward motion.
FIGURE 19
The epicycle-deferent systems explains why the planets appear brighter. It is when they retrogress that they are closer to the Earth.
The problem with this system is that the epicycle was made to revolve exactly 3 times and the retrograde loops always seem to occur in the same places. In a real life this is not so true, it varies slightly, it averages more than 3 retrograde lops in each trip around the ecliptic.
Although the systems described and explained one of the main problems, there were other irregularities to be considered.
In the cycle of the diurnal motion, a planet is not always seen at the same position on the ecliptic as where the model says it should be.
Ptolemaic system:
- Minor epicycle
- A deferent whose center is displaced from Earth. (eccentric, displaced circle).
Ptolemy was the first to put together a set of compounded circles to account for the observed quantitative regularities in the motions of all 7 planets.
Then the problem of the planets became a problem of design.
None of the theories mathed the observations that had been made. The planets were the greatest problem.
It took 1800 years to change theories. It was like if every astronomer in that time was seeking through the same spectacles.
The logical structure of a scientific revolution:
“A conceptual scheme, believed because it is economical, fruitful and cosmologically satisfying, finally leads to results that are incompatible with observation; belief must then be surrendered and a new theory adopted; after this the process starts again.”
Chapter 3
The Two-Sphere Universe in Aristotelian Thought
4th century BC Aristotle:
“But even more important than his many scattered substantive contributions was his organization of all knowledge into a systematic and a coherent whole.”
He was searching for a kind of consilience, although he did not quite make it.
Aristotelian universe:
How is it that no one had not thought about Earth being in the center of the universe?
Full universe / Plenum:
In the old times, astronomy was closely linked to astrology.
There were to kinds of astrologers:
The educated people all relied on astrology. And it was in this time that the theories for Earth being at the center of the universe became stronger.
“We like to forget that many of the concepts in which we believe were painfully drummed into us in our youth.” “We too easily take them as natural and indubitable products of our own unaided perceptions, dismissing concepts different from our own as errors, rooted in ignorance or stupidity and perpetuated by blind obedience to authority."
4th century BC Aristotle:
“But even more important than his many scattered substantive contributions was his organization of all knowledge into a systematic and a coherent whole.”
He was searching for a kind of consilience, although he did not quite make it.
Aristotelian universe:
- All was contained within the sphere of the stars and there was absolutely nothing outside the sphere, not even space.
- Self-contained and self-sufficient.
- The largest part of the interior of the universe is filled with one element, the aether, which is pure and unalterable, transparent and weightless. (planets and stars are made from this)
- Terrestrial elements: earth, water, fire and air.
- Earth did not move.
- All of the elements try to reach back to their natural positions: earthly materials try to reach back to the ground and fire tries to reach back to the sky.
- The Earth and the universe have the same center.
- Earth is spherical because of the stars and the eclipses of the moon.
How is it that no one had not thought about Earth being in the center of the universe?
Full universe / Plenum:
- Nature will always act to prevent the formation of a vacuum (horror vacui)
- Matter and space are inseparable.
In the old times, astronomy was closely linked to astrology.
There were to kinds of astrologers:
- Natural: predicted the future of the stars from their past and present.
- Judicial: predicted the future of men.
The educated people all relied on astrology. And it was in this time that the theories for Earth being at the center of the universe became stronger.
“We like to forget that many of the concepts in which we believe were painfully drummed into us in our youth.” “We too easily take them as natural and indubitable products of our own unaided perceptions, dismissing concepts different from our own as errors, rooted in ignorance or stupidity and perpetuated by blind obedience to authority."
Chapter 4
Recasting the Tradition: Aristotle to the Copernicans.
Aristotle was the last great cosmologist of antiquity and Ptolemy was the last great astronomer.
Only 13 centuries after Ptolemy’s death did the Copernican Revolution kick in.
In all this time the basic knowledge of the universe did not change, only small details, strengths and weaknesses in those concepts.
Loss of ancient science:
1. Slow decline in the quality and quantity of scientific activity.
2. A disappearance of traditional learning (Muslims and the empire).
The Islamic civilization took all the power when Christendom was falling, which later recovered all the Greek work through translations of Arabic. This kept growing and when Europe gained power they used these texts to teach at the universities.
But new problems arose, the translations weren’t very textual and did not stay faithful to the original (they went from Greek to Syrian to Arab to Latin). Each interpretation varied.
Aristotle was the last great cosmologist of antiquity and Ptolemy was the last great astronomer.
Only 13 centuries after Ptolemy’s death did the Copernican Revolution kick in.
In all this time the basic knowledge of the universe did not change, only small details, strengths and weaknesses in those concepts.
Loss of ancient science:
1. Slow decline in the quality and quantity of scientific activity.
2. A disappearance of traditional learning (Muslims and the empire).
The Islamic civilization took all the power when Christendom was falling, which later recovered all the Greek work through translations of Arabic. This kept growing and when Europe gained power they used these texts to teach at the universities.
But new problems arose, the translations weren’t very textual and did not stay faithful to the original (they went from Greek to Syrian to Arab to Latin). Each interpretation varied.
Bifurcation of astronomy and cosmology:
“Though science played a large part in the thought of the later middle ages, the dominant intellectual forces were theological, and the practice of science in a theological milieu shifted both the strengths and weaknesses of the scientific tradition.”
“The churches attitude toward science and about the structure of the universe was a determining factor in the progress or stagnation of astronomy.”
Most of the time the church was antiscientific. They believed they did not need science to explain anything because everything was derived from God.
Astronomy was particularly scorned because of its relation to astrology.
“From the fourth century on, Aristotle, Ptolemy and other Greek writers had been attacked by churchmen because of the conflict between their cosmological opinions and scripture.”
One of the first to start the reconciliation of the Aristotelian universe and the church was St. Thomas Aquinas. He tried to fit into Aristotle’s theory much of what the bible said.
Dante’s nine spheres = planets?
Dante related the divine comedy with the Aristotelian universe, Hipparchus’ epicycles and the church.
By the time Copernicus was born, it was the central decades of the Renaissance and Reformation.
A reform of the calendar was a push (made by Copernicus) to reform astronomy.
Copernicus came from a neoplatonic tradition.
As well as Kepler.
“No system so complex and cumbersome could represent the true mathematical order of nature.”
That’s what they thought of the Ptolemaic system.
Neo-Platonism believed that God could be compared with the sun. This might have helped Copernicus think about a central sun.
“Though science played a large part in the thought of the later middle ages, the dominant intellectual forces were theological, and the practice of science in a theological milieu shifted both the strengths and weaknesses of the scientific tradition.”
“The churches attitude toward science and about the structure of the universe was a determining factor in the progress or stagnation of astronomy.”
Most of the time the church was antiscientific. They believed they did not need science to explain anything because everything was derived from God.
Astronomy was particularly scorned because of its relation to astrology.
“From the fourth century on, Aristotle, Ptolemy and other Greek writers had been attacked by churchmen because of the conflict between their cosmological opinions and scripture.”
One of the first to start the reconciliation of the Aristotelian universe and the church was St. Thomas Aquinas. He tried to fit into Aristotle’s theory much of what the bible said.
Dante’s nine spheres = planets?
Dante related the divine comedy with the Aristotelian universe, Hipparchus’ epicycles and the church.
By the time Copernicus was born, it was the central decades of the Renaissance and Reformation.
- The feudal monarchy was replaces with nation-state.
- New commercial aristocracy rivaled old aristocracies of church and nobility.
- Luther and Calvin led revolts against the Catholic Church.
A reform of the calendar was a push (made by Copernicus) to reform astronomy.
Copernicus came from a neoplatonic tradition.
As well as Kepler.
“No system so complex and cumbersome could represent the true mathematical order of nature.”
That’s what they thought of the Ptolemaic system.
Neo-Platonism believed that God could be compared with the sun. This might have helped Copernicus think about a central sun.
Chapter 5
Copernicus' Innovation
De Revolutionibus Orbuim Celestium was published in 1543.
“In its consequences the De Revolutionibus is undoubtedly a revolutionary work. From it derives a fundamentally new approach to planetary astronomy, the first accurate and simple solution of the problem of the planets, and ultimately… a new cosmology.”
The elements which the Copernican Revolution is famous for:
“The significance of the De Revolutionibus lies, then, less in what it says itself than in what it caused others to say.”
“The De Revolutionibus was written to solve the problem of the planets, which, Copernicus felt, Ptolemy and his successors had left unsolved.”
This is why he discovered the system being Earth centered.
Mathematicians (according to Copernicus) are those who modifies old astronomy.
“It was mathematical planetary astronomy, not cosmology of philosophy that Copernicus found monstrous, and it was he reform of mathematical astronomy that compelled him to move the Earth.”
If Copernicus had questioned the data given to him, he could’ve made a better result. But the information that was handed down to Copernicus was very bad.
BUT.. Copernicus wasn't the first to think about the Earth moving. He even says in his letter that he was influenced by other philosophers. Example: Plutarch’s passage.
De Revolutionibus:
Book 1
1)
2) a circular motion of the Earth (the Earth rotates in a diurnal motion, wanders and is a planet)(with this he can explain retrograde motion)
7)
“Copernicus endowed Earth with three simultaneous circular motions: a diurnal axial rotation, an annual orbital motion and an annual conical motion of the axis.”
Parallatic motion:
Each star should seem slightly to change its position on the sphere of the stars, during the course of a year.
PICTURE FIGURE · PG165
Things that Copernicus solved which the old astronomers had trouble with:
But really Copernicus’ system could not predict the motion of the planets. At the end it was not more accurate than Ptolemy’s system or no more simple.
So Copernicus’ solar system wasn't really solar. The center of the universe was a little of the suns center.
Although his theories / system was a failure he did help others imagine a s un centered universe. And this led to the simple and accurate solution that Copernicus sought.
10) order of the heavenly bodies (farther away, they move more slowly) (the closer they are the faster)
“Copernicus is neither an ancient nor a modern but rather a Renaissance astronomer in whose work the two traditions merge.”
“For Copernicus’ sixteen-and-seventeenth-century followers, the primary importance of the De Revolutionibus derived from its single novel astronomical consequences, the new harmonies, which Copernicus had derived from that new concept.”
De Revolutionibus Orbuim Celestium was published in 1543.
“In its consequences the De Revolutionibus is undoubtedly a revolutionary work. From it derives a fundamentally new approach to planetary astronomy, the first accurate and simple solution of the problem of the planets, and ultimately… a new cosmology.”
The elements which the Copernican Revolution is famous for:
- Easy and accurate computations of planetary position.
- Elimination of epicycles and eccentrics
- Dissolution of spheres
- Sun as a star
- Infinite expansion of the universe
“The significance of the De Revolutionibus lies, then, less in what it says itself than in what it caused others to say.”
“The De Revolutionibus was written to solve the problem of the planets, which, Copernicus felt, Ptolemy and his successors had left unsolved.”
This is why he discovered the system being Earth centered.
Mathematicians (according to Copernicus) are those who modifies old astronomy.
“It was mathematical planetary astronomy, not cosmology of philosophy that Copernicus found monstrous, and it was he reform of mathematical astronomy that compelled him to move the Earth.”
If Copernicus had questioned the data given to him, he could’ve made a better result. But the information that was handed down to Copernicus was very bad.
BUT.. Copernicus wasn't the first to think about the Earth moving. He even says in his letter that he was influenced by other philosophers. Example: Plutarch’s passage.
De Revolutionibus:
Book 1
1)
- Universe is spherical (all things tend to assume this shape)
- Earth is spherical (all sides fall towards the center)
- Earth, with water form one sphere (each and water are essential for a composition of a sphere)
- Motion of heavenly bodies is circular and uniform. (rotation is natural to a sphere. Earth might be the center of the universe)
2) a circular motion of the Earth (the Earth rotates in a diurnal motion, wanders and is a planet)(with this he can explain retrograde motion)
7)
- why people believed Earth was at rest (Earth was the heaviest element and all things move toward it)
- Why past arguments were wrong (assume universe to be infinite)
- The Earth has more than one motion.
“Copernicus endowed Earth with three simultaneous circular motions: a diurnal axial rotation, an annual orbital motion and an annual conical motion of the axis.”
Parallatic motion:
Each star should seem slightly to change its position on the sphere of the stars, during the course of a year.
PICTURE FIGURE · PG165
Things that Copernicus solved which the old astronomers had trouble with:
- Retrograde motion (solved by making the Earth spin)
- Variation of time required to circle the elliptic (Earth makes a 1, ¼ eastward revolution and the apparent position of the planet changes.)
But really Copernicus’ system could not predict the motion of the planets. At the end it was not more accurate than Ptolemy’s system or no more simple.
So Copernicus’ solar system wasn't really solar. The center of the universe was a little of the suns center.
Although his theories / system was a failure he did help others imagine a s un centered universe. And this led to the simple and accurate solution that Copernicus sought.
10) order of the heavenly bodies (farther away, they move more slowly) (the closer they are the faster)
“Copernicus is neither an ancient nor a modern but rather a Renaissance astronomer in whose work the two traditions merge.”
“For Copernicus’ sixteen-and-seventeenth-century followers, the primary importance of the De Revolutionibus derived from its single novel astronomical consequences, the new harmonies, which Copernicus had derived from that new concept.”
Chapter 6
The Assimilation of Copernican Astronomy
Copernicus died the same year his book was published.
Copernicus made his book unreadable to all except the erudite astronomers. So his ideas took a while to spread.
Most astronomers took into account Copernicus’ mathematical system, but ignored the motion of the Earth; until the beginning of the 17th century.
Mostly everyone was against Copernicus. From astronomers, to poets, to religious people, etcetera.
“The Earth’s motion, it was said, violated the fist dictate of common sense; it conflicts with long-established laws of motion; it has been suggested merely ‘to save better of the appearance’ a ridiculously minuscule incentive for revolution.”
Anti-Copernican arguments of the church:
but the earth remains forever.
The sun rises and the sun sets,
and hurries back to where it rises.
When the catholic church joined against Copernicanism, this became heresy.
“Copernicanism required a transformation in man’s view of his relation to God and the bases of his morality.”
Tyco Brahe:
A great opponent of Copernicanism. Because of him, Copernicanism was also postponed.
He did not innovate in astronomical concepts, but he built new instruments and was a great naked eye observer.
He gathered more accurate data.
“Trustworthy, extensive, and up-to-date data are Brahe’s primary contribution to the solution of the problem of the planets.”
PICTUYRE OF TYCHONIC SYSTEM
Tychonic system:
“It retained the mathematical advantages of Copernicus’ system without the physical cosmological and theological drawbacks.”
The Tychonic system, all though against Copernicanism, helped break the barriers of thought from Aristotelian astronomy. It also helped expand the knowledge of the mathematical theories of the Copernican astronomy and created new data, which helped Kepler.
Johannes Kepler:
A Copernican. Kepler defended all of Copernicus’ arguments, but with more lengths and diagrams.
“For the first time the full force of the mathematical arguments for the new astronomy was demonstrated.”
He helped polish all of the problems that appeared in the De Revolutionubus. He also tried to include Brahe’s observations.
He concluded that no system based on circles could solve the problem, which is why he finally used elliptical orbits.
Kepler’s laws:
1. The planets move in simple elliptical paths, and the sun occupies one of the two foci of each elliptical orbit.
2. The orbital speed of each planet varies in such a way that a line joining the planets to the sun sweeps through equal areas of the ellipse in equal intervals of time.
“For the first time the predictions are as accurate as the observations.”
Kepler “believed that all of nature exemplified simple mathematical regularities which it was the scientist’s task to discover.”
Galileo:
“Galileo Galilei viewed the heavens through a telescope for the first time, and as a result contributed to astronomy the first qualitatively new sort of data that it had acquired since antiquity.”
With this new observations he helped contribute to Copernicanism:
“The first unique role of the telescope was providing generally accessible and non-mathematical documentation for the Copernican point of view.”
The greatest important contribution of Galileo to astronomy was that he popularized it and more specifically he popularized Copernicanism.
“though the telescope argued much, it proved nothing.”
People still refused to believe that it work and that what it was trying to prove was true. Some said it was just an illusion and others that it was just fake.
Copernicus died the same year his book was published.
Copernicus made his book unreadable to all except the erudite astronomers. So his ideas took a while to spread.
Most astronomers took into account Copernicus’ mathematical system, but ignored the motion of the Earth; until the beginning of the 17th century.
Mostly everyone was against Copernicus. From astronomers, to poets, to religious people, etcetera.
“The Earth’s motion, it was said, violated the fist dictate of common sense; it conflicts with long-established laws of motion; it has been suggested merely ‘to save better of the appearance’ a ridiculously minuscule incentive for revolution.”
Anti-Copernican arguments of the church:
- Ecclesiastes 1:4-5
but the earth remains forever.
The sun rises and the sun sets,
and hurries back to where it rises.
- Psalm 93
When the catholic church joined against Copernicanism, this became heresy.
“Copernicanism required a transformation in man’s view of his relation to God and the bases of his morality.”
Tyco Brahe:
A great opponent of Copernicanism. Because of him, Copernicanism was also postponed.
He did not innovate in astronomical concepts, but he built new instruments and was a great naked eye observer.
He gathered more accurate data.
“Trustworthy, extensive, and up-to-date data are Brahe’s primary contribution to the solution of the problem of the planets.”
PICTUYRE OF TYCHONIC SYSTEM
Tychonic system:
“It retained the mathematical advantages of Copernicus’ system without the physical cosmological and theological drawbacks.”
The Tychonic system, all though against Copernicanism, helped break the barriers of thought from Aristotelian astronomy. It also helped expand the knowledge of the mathematical theories of the Copernican astronomy and created new data, which helped Kepler.
Johannes Kepler:
A Copernican. Kepler defended all of Copernicus’ arguments, but with more lengths and diagrams.
“For the first time the full force of the mathematical arguments for the new astronomy was demonstrated.”
He helped polish all of the problems that appeared in the De Revolutionubus. He also tried to include Brahe’s observations.
He concluded that no system based on circles could solve the problem, which is why he finally used elliptical orbits.
Kepler’s laws:
1. The planets move in simple elliptical paths, and the sun occupies one of the two foci of each elliptical orbit.
2. The orbital speed of each planet varies in such a way that a line joining the planets to the sun sweeps through equal areas of the ellipse in equal intervals of time.
“For the first time the predictions are as accurate as the observations.”
Kepler “believed that all of nature exemplified simple mathematical regularities which it was the scientist’s task to discover.”
Galileo:
“Galileo Galilei viewed the heavens through a telescope for the first time, and as a result contributed to astronomy the first qualitatively new sort of data that it had acquired since antiquity.”
With this new observations he helped contribute to Copernicanism:
- Infinite universe (discovery of more stars)
- By observing the sun (spots) and the moon (crates) it showed that the celestial region was imperfect.
- 4 principal moons of Jupiter which moved around the planet.
“The first unique role of the telescope was providing generally accessible and non-mathematical documentation for the Copernican point of view.”
The greatest important contribution of Galileo to astronomy was that he popularized it and more specifically he popularized Copernicanism.
“though the telescope argued much, it proved nothing.”
People still refused to believe that it work and that what it was trying to prove was true. Some said it was just an illusion and others that it was just fake.