Scientific Awakening--Copernicus-Brahe-Kepler

[ Islamic Background ] [ Copernicus-Brahe-Kepler ] [ Galileo ] [ Newton ] [ Enlightenment ]

Have a look at Ptolemy v. Copernicus and Galileo
go on and watch parts 2,3,4



The "conventional wisdom" of 15th century Europe placed man (created in God's image) at the center of the universe inhabiting a flat, stationery earth around which the moon, planets, and sun revolved in perfectly circular orbits. Supported by the Bible, Ptolemy, Aristotle, and the Church, this anthropomorphic and geocentric view conformed comfortably to cherished traditions and common sense. Although ancients such as Aristarchus of Samos (310-230 BCE) postulated a round earth, Aristotle and St. Thomas Aquinas held that it was flat and at the center of God's creation. Celestial bodies, the conventional wisdom held, were composed of an ethereal substance (not matter,) explaining why they did not crash into the earth (i.e. what goes up must come down.)

(Berger. "Ptolemy Model.")


Copernicus (1473-1543)

Nicolaus Copernicus was born in Poland as Mikolaj Kopernik and began latinizing the spelling of his name as a student at the University of Krakow. During his lifetime, Columbus discovered the New World, Luther broke with the Catholic Church, the Wars of Religion erupted, Michelangelo painted the ceiling of the Sistine Chapel, Henry VIII embarked upon his marital and religious journey. It was Copernicus who "displaced Earth as the center of the universe and...challenged the Bible, the church and...the revered Aristotle...." (Wilford 13)

(Linder. "Nicolaus Copernicus")
5 minute Cloud Bio of Copernicus < >

Traditionally viewed as the founding figure of the Scientific Awakening, Copernicus challenged the Ptolemiac-Aristotelian-Church view of the universe--a stationary earth in a hermetically sealed geocentric universe. He proposed, instead, a heliocentric/sun-centered model in which the earth moved, rotating on its own axis as it revolved around the sun (see left.) Scholars and historians now believe that Copernicus was familiar with the writings of both Aristarchus and Muslim astronomer Ibn al-Shatir. (Paar 1) His major work, On the Revolution of Heavenly Spheres (De revolutionibus orbium coelestium) represented a lifetime of study dating from 1514. However, given the turmoil of the Reformation and Wars of Religion, Copernicus chose to withhold publication of his conclusions. An enthusiastic supporter, George Rheticus, urged him to go forward, which Copernicus did in 1543. Legend suggests that he was on his virtual deathbed when he saw a printed copy of what became an intellectual (not to mention religious) bombshell.

(Yost and Daunt 1) < >--gone, alas


The gifted Danish astronomer and mathematician Tycho Brahe (1546-1601) could not swallow the Copernican model of the universe, and denied it to the end, but his great contribution lay in a commitment to accurate observation of the heavens. On the tiny island of Hven, and without a telescope, he devised new and better instruments, made nightly observations, and fashioned the best observatory in Europe. Historians credit Tycho with making the "most accurate naked eye astronomical measurements of his day" (Weisstein 1). These observations led him to conclude that the heavens were not immutable and unchanging, as the conventional wisdom maintained. Though a Dane and a Protestant, he moved to Prague in 1599 where he served as Imperial Mathematician at the court of Holy Roman Emperor, Rudolph II (Van Helden 1-2). There, he hired and trained Johannes Kepler (graphic, Weisstein 1).
For those of you who are clamoring to know about the odd and colorful Tycho, here goes: The Danish spelling of his name was Tyge (Latinized to Tucho or Tycho.) A highly educated Danish aristocrat, Tycho attended five universities, picking up degrees along the way, and traveled throughout the Holy Roman Empire. He prided himself on being a gifted mathematician, the best he ever met, and consequently lost his nose in a duel with a student in 1570. He wore various fake noses for the rest of his life, favoring those made of gold and silver. Scholars, astronomers, astrologers and the curious visited Tycho at his island observatory.

Thank you, Gabby Occhipinti for finding great image of "the nose"
image source < >


Tycho invented and calibrated sophisticated instruments for his celestial observations and was invited by Emperor Rudolph II to come to his imperial court in Prague to serve as imperial mathematician and astrologer. He invited Johnannes Kepler to join him there as his assistant, though the two men were highly competitive with one another as to which was the more gifted mathematician and astrologer. Tycho's "mountains and mountains of evidence" made possible Kepler's later theories on celestial/heavenly/planetary motion.

image source < >--gone, alas


Johannes Kepler (1571-1630) defended the Copernican model rejected by his mentor Tycho Brahe in a 1596 work, Mysterium Cosmographicum (Mystery of the Cosmos.) Born and raised a devout Lutheran in the staunchly Catholic Holy Roman Empire, which was wracked by the Thirty Years War during much of his lifetime, Kepler fled from Graz to Prague to Linz. He found a degree of protection in Prague under the mentorship of Tycho. Using the instruments and detailed observational data of the great Tycho, Kepler discovered that the orbit of Mars was an ellipse not a "perfect" circle. (Koch 2) After Tycho's death, he assumed the title of Imperial Mathematician in the court of Rudolph and named his planetary tables after the emperor. Kepler quickly adopted and adapted the telescope, invented by Johann Lippershey in 1608. Carrying out his own observations, he also began a correspondence with Galileo, publishing Astronomia Nova (The New Astronomy) in 1609. Here he introduced his theories of planetary motion, supporting Copernicus' heliocentrism though rejecting the latter's "perfect" circular motion of the heavenly bodies.

(graphic, Koch 1)


Over the course of a lifetime of research, Kepler devised new theories (laws?) explaining celestial motion that did not conform to the old Aristotelian model.

Kepler's First Law states:
The orbits of the planets are ellipses, with the Sun at one focus of the ellipse.

Kepler's Second Law states:
The line joining the planet to the Sun sweeps out equal areas in equal times as the planet travels around the ellipse.



Kepler's Third Law states:
The ratio of the squares of the revolutionary periods for two planets is equal to the ratio of the cubes of their semimajor axes (!)
(Graphics from Yost and Daunt 2-4)
For an animated look at Kepler's elliptical orbits, visit
Alas, disappeared--dang!



Youtube (thank you, youtube)
had some useful sites that demonstrate Kepler's three laws of celestial/planetary motion
This clip was put together by high school students (not unlike you)
Try this one < >
Ask Mr Rockman if these explanations are correct.

Have a look at this youtube that illustrates elliptical orbit
< >
Kepler's 2nd Law
< >
Kepler's 3rd Law
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Copernicus and Kepler discredited some of the conventional wisdom and/or supported earlier challenges:
a round earth replaced the old flat earth view;
heliocentrism replaced geocentrism;
an earth in motion (rotating and revolving) replaced a stationary one;
elliptical orbits replaced circular ones.
These discoveries, coming at a time of religious turmoil, upset traditional
Catholics as well as Lutherans and Calvinists who took the Bible--the Word of God--
as literal and absolute truth.


Background Image: Linder, Douglas. "Selected Images--Copernican Model." The Trial of Galileo. Online Available
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Berger, Daniel." Models of the solar system." Online Available
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Koch, David."Johannes Kepler: His Life, His Laws and Times." Kepler Mission. Online Available
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Office of the Vice-President of Computing of Rice University. The Galileo Project. Online Available.
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Paar, D. "Nicolaus Copernicus." Univesity of Zagreb Department of Physics. Online Available
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Weisstein, Erick W. "Brahe, Tycho (1546-1601.)" Online Available
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Wilford, John N. "Chasing Copernicus." The New York Times Book Review. July 18, 2004.

Yost and Daunt. "The Copernican Model: A Sun-Centered Solar System." Department of Astronomy, University of Tennessee. Online Available
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McKee, Peggy. "Copernicus-Brahe-Kepler." The Scientific Awakening. Updated. January 13, 2015 . Online Available.
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(McKee. "Copernicus-Brahe-Kepler.")