Mercurio raised his hand and said something that was almost completely tranlated by a house-elf by his side. "He was a Tuscan psylosopher and astronomer. He was born in Pisa, February 15, 1564 – and died at Arcetri, January 8, 1642. Lived in Padua most his life though."

Evy silently agreed with her fellow classmates.

"I also know that he used to drop lead, wood, and paper balls from the top of the Pisa tower, and that it's that way that he discovered that all of these balls, whatever their weight was, had the same movement. Also, even though he was an admirer of Copernic's work, he taught his students that the Earth was the center of the solarsystem because he didn't want to attract attention to himself I guess. Concerning astronomy, Galilei was the one to discover Jupiter's satellites and he also made the remark that the moon wasn't a perfect sphere."

Evy didn't know if she had to continue speaking, but she really wanted to gain points for Hufflepuffs since they had lost so many in Divination.

"He also observed that the diameter of Venus could vary, and that way he emmited the hypothesis that Venus moved around the Sun. Galilei published an essay concerning the different systems of the world called: *Evy took a breathe* Dialogue où dans les rencontres de quatre journées il est disserté au sujet des deux principaux systèmes du monde, le ptoléméen et le copernicien, en proposant sans aucune détermination les raisons philosophiques et naturelles tant en faveur de l’une que de l’autre des parties. That could win an award for the longest title ever written, and even though it would be a pleasure for me to translate it to you, I guess it would just annoy you more than anything, right? But if you insist..."

Evy chuckled.

"Dialogue où dans les rencontres de quatre journées il est disserté au sujet des deux principaux systèmes du monde, le ptoléméen et le copernicien, en proposant sans aucune détermination les raisons philosophiques et naturelles tant en faveur de l’une que de l’autre des parties means something like Dialogue in which, in the meeting of four days, it is discoursed on the subject of the two principal systems of the Universe, the ptolemian and copernician, proposing without any determination the philosophical and natural reasons in the favor of both parties."

Evy smiled shyly.

Thats right! 3 points.

And a very well done to Evy, 12 points for all that!

Galileo was taught by monks at Vallombrosa and then entered the University of Pisa in 1581 to study medicine. He soon turned to philosophy and mathematics, leaving the university without a degree in 1585. For a time he tutored privately and wrote on hydrostatics and natural motions, but he did not publish. In 1589 he became professor of mathematics at Pisa, where he is reported to have shown his students the error of Aristotle’s belief that speed of fall is proportional to weight, by dropping two objects of different weight simultaneously from the Leaning Tower. His contract was not renewed in 1592, probably because he contradicted Aristotelian professors. The same year, he was appointed to the chair of mathematics at the University of Padua, where he remained until 1610.

Little attention was paid to the Copernican, or heliocentric, system until Galileo discovered evidence to support it. Long a secret admirer of Copernicus’s work, Galileo saw his chance to test the Copernican theory of a moving Earth when the telescope was invented in the Netherlands.

He turned from speculative physics to careful measurements, discovered the law of falling bodies and of the parabolic path of projectiles, studied the motions of pendulums, and investigated mechanics and the strength of materials. He showed little interest in astronomy, although beginning in 1595 he preferred the Copernican theory that the earth revolves around the sun—to the Aristotelian and Ptolemaic assumption that planets circle a fixed earth. Only the Copernican model supported Galileo’s tide theory, which was based on motions of the earth. In 1609 he heard that a spyglass had been invented in Holland. In August of that year he presented a telescope, about as powerful as a modern field glass, to the doge of Venice. Its value for naval and maritime operations resulted in the doubling of his salary and his assurance of lifelong tenure as a professor.

So now with his telescope he turned it skyward, and discovered the phases of Venus, indicating that this planet revolves around the Sun; he also discovered four moons revolving around Jupiter, as well as the rings of Saturn. Convinced that some bodies, at least, do not circle Earth, he began to speak and write in favor of the Copernican system. His attempts to publicize the Copernican system caused him to be tried by the ecclesiastical authorities. Although he was forced to repudiate his beliefs and writings, the powerful theory could not be suppressed.

He discovered mountains and craters on the moon. He also saw that the Milky Way was composed of stars, and he discovered the four largest satellites of Jupiter. He published these findings in March 1610 in The Starry Messenger (trans. 1880).

So as you can see, Galileo was basically forced to deny his findings. Opinions at the time were very much against the copernican theory, although he had found so much evidence to support it.

Does anyone know why his findings were so disputed? It has something to do with Aristotle...

(ow, Gero, two seconds too late =P)

*raise hand* "The work of Galileo is considered to be a significant break from that of Aristotle and the curch which used Aristotlelian beliefs as main base of knowledge. Galileo proved lost of Aristotelian theories wrong in lots of things. For example, he was a follower of Copernicus' theory that the Sun was the centre of the galaxy and we, the earth, round it up and not the other way round. This theory is called heliocentrism. Since Galileo defied Aristotle's thinking he was therefore defing the curch (even though he was a catholic). In addition, his conflict with the Roman Catholic Church is taken as a major early example of the conflict of religion and freedom of thought, particularly with science, in Western society.

Anyway, to name a few things Galileo preved Aristotle wrong and which caused his impopularity with society and the curch: One of the most famous stories about Galileo is that he dropped balls of different masses from the Leaning Tower of Pisa to demonstrate that their velocity of descent was independent of their mass (excluding the limited effect of air resistance). This was contrary to what Aristotle had taught: that heavy objects fall faster than lighter ones, in direct proportion to weight. He also concluded that objects retain their velocity unless a force -- often friction -- acts upon them, refuting the accepted Aristotelian hypothesis that objects "naturally" slow down and stop unless a force acts upon them.

"There was the smaller contradictions. Like, when refering to technology as distinct from pure physics, which is not the same distinction as made by Aristotle, who would have considered all Galileo's physics as techne or useful knowledge, as opposed to episteme, or philosophical investigation into the causes of things. Also, Galileo Galilei was the first to report lunar mountains and craters, whose existence he deduced from the patterns of light and shadow on the Moon's surface. He even estimated the mountains' heights from these observations. This led him to the conclusion that the Moon was "rough and uneven, and just like the surface of the Earth itself", and not a perfect sphere as Aristotle had claimed.

"Going back to the heliocentrism theory, the one that caused the most troubles: on January 7, 1610 Galileo discovered Jupiter's four largest satellites (moons): Io, Europa, Ganymede, and Callisto. The demonstration that a planet had smaller planets orbiting it was problematic for the orderly, comprehensive picture of the geocentric model of the universe, in which everything circled around the Earth. Besides, Galileo noted that Venus exhibited a full set of phases like the Moon. Because the apparent brightness of Venus is nearly constant, Galileo reasoned that Venus could not be circling the Earth at a constant distance."

Nadia sighed.

"Within other instereting facts, Galieo is reputed to have invented the telescope, but that's quite inacurate; he took the idea from other people and put it under his name to sell it and afford his investigations. He did improve the telescope though, making it smaller and easier to carry plus was the first one to use to to watch the sky - before, I think, it was used on boats to gaze to find the shores, if I'm not much mistaken.

She smiled shippishly. "That's pretty much it. The fact that the church used Aristotlelian books as source of knowledge - something they did a lot at that time, quoting eldery wise man -, made that the new ideas looked against the church when in fact that was not it. The helicentrism theory was the one who suffered the most. We must remember that at that time it was believed that the centre of the universe should be the earth because then it would be proving that God is always watching us. Galileo was asked to take back what he said, and he did to avoid being hanged... and it is said that his last words, when about to die, were "and yet it moves"."

Mithos raised his hand "It was because of his disagreement with Aristotle."

Francis raised her hand. "More importantly, is the relationship between Aristotle and the church, and then Galileo and the church. Galileo contribute to a rejection of blind allegiance to an authoritative leader, such as the church and Aristotle, in matters of the separation of science and religion/philosophy"

Serena raised her hand.

Aristotle believed that the laws governing the motion of the heavens were a different set of laws than those that governed motion on the earth. Galileo's concept of inertia was quite contrary to Aristotle's ideas of motion: in Galileo's dynamics the arrow (with very small frictional forces) continued to fly through the air because of the law of inertia, while a block of wood on a table stopped sliding once the applied force was removed because of frictional forces that Aristotle analyzed incorrectly.

Also, Galileo's extensive telescopic observations of the heavens made it more and more plausible that they were not made from a perfect, unchanging substance. In particular, Galileo's observational confirmation of the Copernican hypothesis suggested that the Earth was just another planet, so maybe it was made from the same material as the other planets.

Galileo laid the groundwork to overthrow the physics of Aristotle, in addition to his astronomy. It fell to Isaac Newton to bring these threads together and to demonstrate that the laws that governed the heavens were the same laws that governed motion on the surface of the Earth.

Excellent! 10 points to Nadia and 5 to fr2nc1z and Serena.

Professors of philosophy scorned Galileo’s discoveries because Aristotle had held that only perfectly spherical bodies could exist in the heavens and that nothing new could ever appear there. Galileo also disputed with professors at Florence and Pisa over hydrostatics, and he published a book on floating bodies in 1612. Four printed attacks on this book followed, rejecting Galileo’s physics. In 1613 he published a work on sunspots and predicted victory for the Copernican theory. A Pisan professor, in Galileo’s absence, told the Medici (the ruling family of Florence as well as Galileo’s employers) that belief in a moving earth was heretical. In 1614 a Florentine priest denounced Galileists from the pulpit.

This basically means that they didn't like what he had to say, so they banned him and his followers from the church, which at the time was a BIG deal.

Galileo remained silent on the subject for years, working on a method of determining longitudes at sea by using his predictions of the positions of Jupiter’s satellites, resuming his earlier studies of falling bodies, and setting forth his views on scientific reasoning in a book on comets, The Assayer (1623; trans. 1957).In 1624 Galileo began a book he wished to call "Dialogue on the Tides," in which he discussed the Ptolemaic and Copernican hypotheses in relation to the physics of tides.

Despite two official licenses, Galileo was summoned to Rome by the Inquisition to stand trial for "grave suspicion of heresy." This charge was grounded on a report that Galileo had been personally ordered in 1616 not to discuss Copernicanism either orally or in writing. Cardinal Bellarmine had died, but Galileo produced a certificate signed by the cardinal, stating that Galileo had been subjected to no further restriction than applied to any Roman Catholic under the 1616 edict. No signed document contradicting this was ever found, but Galileo was nevertheless compelled in 1633 to abjure and was sentenced to life imprisonment (swiftly commuted to permanent house arrest). The Dialogue was ordered to be burned, and the sentence against him was to be read publicly in every university.

Can we say, bugger!

Galileo’s most valuable scientific contribution was his founding of physics on precise measurements rather than on metaphysical principles and formal logic.

So following on from Galileo was a man called Tycho Brahe. Does anyone know where he was from and the dates of his birth and death?

Tycho Brahe

Born: 14 Dec 1546 in Knudstrup, Denmark
Died: 24 Oct 1601 in Prague, Bohemia (now Czech Republic)

Francis smiled and raised her hand, "Tycho Brahe, most commonly known as Tycho, was born on Dec 14th in 1546 in Knudstrup, Denmark. He died on Oct 24th in 1601 in Prague, Bohemia -- which is now known as the Czech Republic. He was a Danish noble man, who was known in the areas of astronomy and alchemy. Also, his most famous assistant was Keppler"

Serena added more about him.

Tycho Brahe's contributions to astronomy were enormous. He not only designed and built instruments, he also calibrated them and checked their accuracy periodically. He thus revolutionized astronomical instrumentation. He also changed observational practice profoundly. Earlier astronomers had been content to observe the positions of planets and the Moon at certain important points of their orbits, Tycho and his cast of assistants observed these bodies throughout their orbits. This resulted in a number of orbital anomalies never before noticed and were made explicitly by Tycho. Without these complete series of observations of unprecedented accuracy, Kepler could not have discovered that planets move in elliptical orbits. Tycho was also the first astronomer to make corrections for atmospheric refraction. In general, whereas previous astronomers made observations accurate to perhaps 15 arc minutes, those of Tycho were accurate to perhaps 2 arc minutes, and it has been shown that his best observations were accurate to about half an arc minute.
Tycho's observations of the new star of 1572 and comet of 1577, and his publications on these phenomena, were instrumental in establishing the fact that these bodies were above the Moon and that therefore the heavens were not immutable as Aristotle had argued and philosophers still believed. The heavens were changeable and therefore the Aristotelian division between the heavenly and earthly regions came under attack, like with Galileo's 'Dialogue', and was eventually dropped. Further, if comets were in the heavens, they moved through the heavens. Up to now it had been believed that planets were carried on material spheres (spherical shells) that fit tightly around each other. Tycho's observations showed that this arrangement was impossible because comets moved through these spheres. Celestial spheres faded out of existence between 1575 and 1625.

"Thanks, professor."

Evy smiled.

"In the book I searched it, it said that Tycho Brahe was born in Skane, Denmark, now Skane, Sweden, in 1546. Is it a different name for Knudstrup? And he died in Prague, Bohemia, in 1601 as the others said."

"A funny fact (well, not really funny lol) is that he lost part of his nose during a duel with another student while he went to University. He created the finest observatory of that time in Hven, and that's where he made most of his researches. Here are some of his work that were published only after his death: On the New and Never Previously Seen Star, Concerning the New Phenomena in the Ethereal World, Instruments for the Restored Astronomy, and Introductory Exercises Toward a Restored Astronomy. He was a reknown scientist at that time. Tycho and his assistant, Johanne Kepler (who was a man by the way) calculated the planetary orbits and their tables were much more accurate then any previous tables. He is known for revolutionizing astronomical instrumentation."

"However, Tycho was not a follower of Copernicus, because he thought that the Earth was the center of the Universe but he used some of his theories and some theories of Aristotle to imagine a new system: the moon and sun revolve around the Earth, but the other planets revolve around the sun."

Excellent! 7 points to Serena, 2 tp Fr2 and 5 to Evy.

Danish astronomer Tycho Brahe observed the Sun, Moon, and planets at his island observatory near Copenhagen and later in Germany. Based on the data compiled by Brahe, his German assistant, Johannes Kepler, formulated the laws of planetary motion, stating that the planets revolve around the Sun, not in circular orbits with uniform motion but in elliptical orbits at varying speeds, and that their relative distances from the Sun can be determined from the observed periods of revolution.

Brahe made precise, comprehensive astronomical measurements of the solar system and more than 700 stars. The data Brahe accumulated was superior to all other astronomical measurements made until the invention of the telescope in the early 17th century. In 1572 he discovered a supernova in the constellation Cassiopeia. After Brahe had spent some time traveling and lecturing, Frederick II, king of Denmark and Norway, offered to provide Brahe with funds to construct and equip an astronomical observatory on the island of Hven (now Ven). Brahe accepted the proposal, and in 1576 construction began on the castle of Uranienborg ("fortress of the heavens"), where for 20 years the astronomer pursued his observations.

How cool would that be!!

Brahe never fully accepted the Copernican theory of the universe and sought a compromise by combining it with the old Ptolemaic system (see Copernican System; Ptolemaic System). In Brahe's system, the five known planets were supposed to revolve around the sun, which, with the planets, circled the earth each year. The sphere of the stars revolved around the immobile earth once a day.
Although Brahe's theory of planetary motion was flawed, the data he accumulated during his life played a crucial role in developing the correct description of planetary motion. Johannes Kepler, who was Brahe's assistant from 1600 until Brahe's death in 1601, used Brahe's data to help him formulate his three laws of planetary motion.

So although Brahe was an important step, it was Kepler that really discovered how the planets all moved.

When and where was he born?

Francis raised her hand. "Kepler was born on December 27, 1571 at the Imperial Free City of Weil der Stadt (now part of the Stuttgart Region in the German state of Baden-Württemberg, 30 km west of Stuttgart's city center). He was introduced to astronomy/astrology at an early age, and developed a love for that discipline that would span his entire life. At age six, he observed the Comet of 1577. In December 1599, Tycho Brahe wrote to Kepler, inviting Kepler to assist him at Benatek outside Prague. After Tycho's death, Kepler was appointed Imperial Mathematician (from November 1601 to 1630) to the Habsburg Emperors. In October 1604, Kepler observed the supernova which was subsequently named Kepler's Star. In January 1612 the Emperor died, and Kepler took the post of provincial mathematician in Linz. On March 8, 1618 Kepler discovered the third law of planetary motion: distance cubed over time squared. He initially rejected this idea, but later confirmed it on May 15 of the same year. On November 15, 1630 Kepler died of a fever in Regensburg."

Johannes Kepler was born on December 27, 1571, at the Imperial Free City of Weil der Stadt (now part of the Stuttgart Region in the German state of Baden-Württemberg, 30 km west of Stuttgart's city center). His grandfather had been Lord Mayor of that town, but by the time Johannes was born, the Kepler family fortunes were in decline. His father earned a precarious living as a mercenary, and abandoned the family when Johannes was 17. His mother, an inn-keeper's daughter, had a reputation for involvement in witchcraft. Born prematurely, Johannes is said to have been a weak and sickly child, but despite his ill health, he was precociously brilliant.
Though he excelled in his schooling, Kepler was frequently bullied, and was plagued by a belief that he was physically repulsive, thoroughly unlikable and, compared to the other pupils, an outsider. This ostracizing probably led him to turn to the world of ideas, as well as an abiding religious conviction, for solace. He died November 15, 1630. He was a German astronomer, mathematician and astrologer.

Anelreas decided to take out a few more scrolls of parchment. She would be taking quite a lot of notes.

Mithos raised his hand "Kepler was born on December 27, 1571"

ooc: do we need to raise our hand before answering a question? 'cause some people don't do it...

No no need to raise you hand, just shout it out to me.

5 points to Fr2 and Nadia.

Kepler accepted Copernican theory (see Copernican System) immediately, believing that the simplicity of Copernican planetary ordering must have been God's plan. In 1594, when Kepler left Tübingen for Graz, Austria, he worked out a complex geometric hypothesis to account for distances between the planetary orbits—orbits that he mistakenly assumed were circular. (Kepler later deduced that planetary orbits are elliptic; nevertheless, these preliminary calculations agreed with observations to within 5 percent.) Kepler then proposed that the sun emits a force that diminishes inversely with distance and pushes the planets around in their orbits. Kepler published his account in a treatise entitled Mysterium Cosmographicum (Cosmographic Mystery) in 1596. This work is significant because it presented the first comprehensive and cogent account of the geometrical advantages of Copernican theory.

While living in Linz, he published his Harmonice Mundi (Harmony of the World, 1619), the final section of which contained another discovery about planetary motion: The ratio of the cube of a planet's distance from the sun and the square of the planet's orbital period is a constant and is the same for all planets.

So with Brahe's help, Kepler made a HUGE advance in Astronomy. But it also took all those before him. The laws of planetary movement are some on the most important parts to the pysical side of Astronomy. Without them we would be clueless.

Next, Sir Isaac Newton. Any interesting facts about him?

Mithos raised his hand "Newton's first major public scientific achievement was the invention, design and construction of a reflecting telescope. He ground the mirror, built the tube, and even made his own tools for the job. This was a real advance in telescope technology, and ensured his election to membership in the Royal Society. The mirror gave a sharper image than was possible with a large lens because a lens focusses different colors at slightly different distances, an effect called chromatic aberration. This problem is minimized nowadays by using compound lenses, two lenses of different kinds of glass stuck together, that err in opposite directions, and thus tend to cancel each other's shortcomings, but mirrors are still used in large telescopes."

Francis said, "Sir Isaac Newton was born on 25 December 1642 and died 20 March 1727 if you use the Julian calendar, which was used during his lifetime. If you use the gregorian calendar he was born on 4 January 1643 and died on 31 March 1727. Newton was an English physicist, mathematician, astronomer, philosopher, and alchemist. However, he was never interested in physics or math, he actually did the work in order to make a living! He actually invented Calculus one day after being stucked on his dorm room when he was 24 yrs old. He had been quarantined on campus all summer."

Mithos looked at Francis and wished he could high five her!

"Sir Isaac Newton was born on January 4, 1643 at Woolsthorpe, near Grantham, Licolnshire, England. He's said to be the greatest scientific genius of all time. He attended Trinity College [Cambridge] in June 1661.

For the next couple of years, the time being around the plague, Newton laid the foundation for elementary differential and integral Calculus, something we all come in counter with some point in our life.

Newton is mainly known for establishing the three laws of gravitations and the laws of motion. With them, he could explain a wide range of hitherto disparate phenomena such as the eccentric orbits of comets, the causes of the tides, and their major variations, the precession of the Earth's axis, and the perturbation of the motion of the Moon by the gravity of the sun.

Newton passed away in London on March 31, 1727." Anelreas spoke, broadly.

Hayley copied down the in depth notes of the astronomers mentioned. She raised her hand, a little late but added, "Umm... just a odd fact, Tycho Brahe died when his bladder exploded while having dinner with the King of England." She smiled at her comment, and looked back down at her parchment.

Mu copied down her notes and sighed.